CSS Scroll Snap Module Level 1

CSS Scroll Snap Module Level 1
CSS Scroll Snap Module Level 1
Editor’s Draft
26 December 2025
More details about this document
This version:
Latest published version:
Previous Versions:
Implementation Report:
Feedback:
CSSWG Issues Repository
Editors:
Matt Rakow
Microsoft
Jacob Rossi
Microsoft
Tab Atkins-Bittner
Google
Elika J. Etemad / fantasai
Apple
Suggest an Edit for this Spec:
GitHub Editor
World Wide Web Consortium
W3C
liability
trademark
and
permissive document license
rules apply.
Abstract
This module contains features to control panning and scrolling behavior with “snap positions”.
CSS
is a language for describing the rendering of structured documents
(such as HTML and XML)
on screen, on paper, etc.
Status of this document
This is a public copy of the editors’ draft.
It is provided for discussion only and may change at any moment.
Its publication here does not imply endorsement of its contents by W3C.
Don’t cite this document other than as work in progress.
Please send feedback
by
filing issues in GitHub
(preferred),
including the spec code “css-scroll-snap” in the title, like this:
“[css-scroll-snap]
…summary of comment…
”.
All issues and comments are
archived
Alternately, feedback can be sent to the (
archived
) public mailing list
www-style@w3.org
This document is governed by the
18 August 2025 W3C Process Document
A test suite and an implementation report will be produced during the
CR period.
The following features are at-risk, and may be dropped during the CR period:
scroll-snap-stop
whether
scroll-snap-type
can cause boxes that are not
scroll containers
to
capture snap positions
(see
discussion
“At-risk” is a W3C Process term-of-art, and does not necessarily imply that the feature is in danger of being dropped or delayed. It means that the WG believes the feature may have difficulty being interoperably implemented in a timely manner, and marking it as such allows the WG to drop the feature if necessary when transitioning to the Proposed Rec stage, without having to publish a new Candidate Rec without the feature first.
1.
Introduction
This section is not normative.
Popular UX paradigms for scrollable content frequently employ paging through content,
or sectioning into logical divisions.
This is especially true for touch interactions
where it is quicker and easier for users to quickly pan through a flatly-arranged breadth of content
rather than delving into a hierarchical structure through tap navigation.
For example, it is easier for a user to view many photos in a photo album
by panning through a photo slideshow view
rather than tapping on individual photos in an album.
However, given the imprecise nature of scrolling inputs
like touch panning and mousewheel scrolling,
it is difficult for web developers to guarantee a well-controlled scrolling experience,
in particular creating the effect of paging through content.
For instance, it is easy for a user to land at an awkward scroll position
which leaves an item partially on-screen when panning.
To this end, this module introduces
scroll snap positions
which enforce the scroll positions that a
scroll container’s
scrollport may end at
after a scrolling operation has completed.
Also, to offer better control over paging and scroll positioning
even when snapping is off,
this module defines the
scroll-padding
property
for use on all
scroll containers
to adjust the
scroll container
’s
optimal viewing region
for the purpose of paging and scroll-into-view operations.
Similarly the
scroll-margin
property can be used on any box
to adjust its visual area
for the purpose of scroll-into-view operations.
1.1.
Module interactions
This module extends the scrolling user interface features defined in
[CSS2]
section 11.1.
None of the properties in this module apply to the
::first-line
and
::first-letter
pseudo-elements.
1.2.
Value Definitions
This specification follows the
CSS property definition conventions
from
[CSS2]
using the
value definition syntax
from
[CSS-VALUES-3]
Value types not defined in this specification are defined in CSS Values & Units
[CSS-VALUES-3]
Combination with other CSS modules may expand the definitions of these value types.
In addition to the property-specific values listed in their definitions,
all properties defined in this specification
also accept the
CSS-wide keywords
as their property value.
For readability they have not been repeated explicitly.
2.
Motivating Examples
In this example, a series of images arranged in a
scroll container
are used to build a photo gallery. In this example the
scroll container
is larger than the photos contained within (such that multiple images may be seen simultaneously), and the image
sizes vary. Using mandatory element-based snap
positions, scrolling will always complete with an image centered in the
scroll container’s
scrollport.
img
/* Specifies that the center of each photo
should align with the center of the scroll
container in the X axis when snapping */
scroll-snap-align: none center
.photoGallery
width
500
px
overflow-x
auto
overflow-y
hidden
white-space
nowrap
/* Requires that the scroll position always be
at a snap position when the scrolling
operation completes. */
scroll-snap-type: x mandatory
div
class
"photoGallery"
img
src
"img1.jpg"
img
src
"img2.jpg"
img
src
"img3.jpg"
img
src
"img4.jpg"
img
src
"img5.jpg"
div
The layout of the scroll container’s contents in the example.
The snapport is represented by the red rectangle, and the snap area is represented by the yellow rectangle. Since the scroll-snap-align is “center” in the inline (horizontal) axis, a snap position is established at each scroll position which aligns the X-center of the snapport (represented by a red dotted line) with the X-center of a snap area (represented by a yellow dotted line).
This example builds a paginated document that aligns each page near to (but not exactly on) the edge of the
scroll container
This allows the previous page to “peek” in from above in order to make the user aware that they are not yet at the top of the document.
Using proximity snap positions instead of mandatory snap positions allows the user to stop halfway through a page (rather than forcing them
to snap one page at a time). However, if a scrolling operation would finish near a snap position, then the scroll will be adjusted to
align the page as specified.
.page
/* Defines the top of each page as the
edge that should be used for snapping */
scroll-snap-align: start none
.docScroller
width
500
px
overflow-x
hidden
overflow-y
auto
/* Specifies that each element’s snap area should
align with a 100px offset from the top edge. */
scroll-padding:
100
px
/* Encourages scrolling to end at a snap position when the
operation completes, if it is near a snap position */
scroll-snap-type: y proximity
div
class
"docScroller"
div
class
"page"
Page 1
div
div
class
"page"
Page 2
div
div
class
"page"
Page 3
div
div
class
"page"
Page 4
div
div
The layout of the scroll container’s contents in the example.
The snapport is represented by the red rectangle
(inset from the top by 100px due to the scroll-padding),
and the snap area is represented by the yellow rectangle.
Since the scroll-snap-align is “start” in the Y axis,
a snap position is established at each scroll position
which aligns the Y-start of the snapport
(represented by a red dotted line)
with the Y-start of a snap area
(represented by a yellow dotted line).
3.
Scroll Snap Model
This module defines controls for
scroll snap positions
which are scroll positions that produce particular alignments
of content within a scroll container.
Using the
scroll-snap-type
property on the relevant
scroll container
the author can request a particular bias
for the scrollport to land on a
snap position
after scrolling operations
(including programmatic scrolls such as the
scrollTo()
method).
Snap positions
are specified
as a particular alignment (
scroll-snap-align
of an element’s
scroll snap area
(its border bounding box, as modified by
scroll-margin
within the
scroll container
’s
snapport
(its scrollport, as reduced by
scroll-padding
).
This is conceptually equivalent to specifying the alignment of
an
alignment subject
within an
alignment container
A scroll position that satisfies the specified alignment
is a
snap position
The act of adjusting the scroll position
of a scroll container’s scrollport
such that it is aligned to a snap area
is called
snapping
and a
scroll container
may be
snapped
to a
snap area
in each axis
if its scrollport is aligned with that
snap area
in that axis
and there is no active scrolling operation.
When there are multiple valid snap areas,
a single one is chosen for each axis when
snapping
according to the algorithm for
selecting between multiple aligned snap areas
The CSS Scroll Snap Module
intentionally does not specify nor mandate
any precise animations or physics used to enforce
snap positions
this is left up to the user agent.
Snap positions
only affect the nearest ancestor
scroll container
on the element’s
containing block chain
4.
Capturing Scroll Snap Areas: Properties on the scroll container
4.1.
Scroll Snapping Rules: the
scroll-snap-type
property
Name:
scroll-snap-type
Value:
none
[ x
block
inline
both ] [ mandatory
proximity ]
Initial:
none
Applies to:
all elements
Inherited:
no
Percentages:
n/a
Computed value:
specified keyword(s)
Canonical order:
per grammar
Animation type:
discrete
The
scroll-snap-type
property specifies
whether a
scroll container
is a
scroll snap container
how
strictly
it
snaps
and
which axes
are considered.
If no strictness value is specified,
proximity
is assumed.
In this example, snapping to headings is enabled in the
block axis
(the y axis for horizontal writing, x axis for vertical writing):
html {
scroll-snap-type: block; /* applied to main document scroller */
h1, h2, h3, h4, h5, h6 {
scroll-snap-align: start; /* snap to the start (top) of the viewport */
UAs must apply the
scroll-snap-type
value set on the root element
to the document viewport.
Note that, unlike
overflow
scroll-snap-type
values are
not
propagated from HTML
body
4.1.1.
Scroll Snap Axis: the
block
inline
, and
both
values
The
axis values
specify what axis(es) are affected by
snap positions
and whether
snap positions
are evaluated independently per axis,
or together as a 2D point.
Values are defined as follows:
The
scroll container
snaps
to
snap positions
in its horizontal axis only.
The
scroll container
snaps
to
snap positions
in its vertical axis only.
block
The
scroll container
snaps
to
snap positions
in its block axis only.
inline
The
scroll container
snaps
to
snap positions
in its inline axis only.
both
The
scroll container
snaps
to
snap positions
in both of its axes independently
(potentially snapping to different elements in each axis).
4.1.2.
Scroll Snap Strictness: the
none
proximity
, and
mandatory
values
The
strictness values
none
proximity
mandatory
specify how strictly
snap positions
are enforced on the
scroll container
(by forcing an adjustment to the scroll position).
Values are defined as follows:
none
If specified on a
scroll container
the
scroll container
must not
snap
mandatory
If specified on a
scroll container
the
scroll container
is required to be
snapped
to a snap position
when there are no active scrolling operations.
If a valid
snap position
exists
then the scroll container must
snap
at the termination of a scroll
(if none exist then no
snapping
occurs).
proximity
If specified on a
scroll container
the
scroll container
may
snap
to a snap position
at the termination of a scroll,
at the discretion of the UA given the parameters of the scroll.
Authors should use mandatory snap positions with consideration of
varyingly-sized screens and (if applicable) varying-sized content.
In particular, although access to snapped elements larger than the scrollport
is handled by the UA,
if authors assign mandatory snapping to non-adjacent siblings,
content in between can become inaccessible
in cases where it is longer than the screen.
A box
captures snap positions
if it is a
scroll container
or
has a value other than
none
for
scroll-snap-type
If a box’s nearest
snap-position capturing
ancestor
on its
containing block chain
is a
scroll container
with a non-
none
value for
scroll-snap-type
that is the box’s
scroll snap container
Otherwise, the box has no
scroll snap container
and its
snap positions
do not trigger
snapping
4.1.3.
Re-snapping After Layout Changes
If the content or layout of the document changes
(e.g. content is added, moved, deleted, resized)
such that the content of a
snapport
changes,
the UA must re-evaluate the resulting
scroll position
and re-snap if required.
If the
scroll container
was
snapped
before the content change
and those same
snap areas
still exist
(e.g. their associated elements were not deleted),
the scroll container must be re-snapped to those same snap areas
after the content change.
snap area
can be
snapped
in each axis,
following the algorithm for
selecting between multiple aligned snap areas
If it is not possible to snap to both
(e.g. if snapping to one resulted in the other being offscreen),
it must prefer the focused box,
followed by the targeted box,
followed by the block axis if neither box is focused or targeted.
Scrolling required by a re-snap operation to a new or different box
must behave and animate the same way as
any other scroll-into-view operation,
including honoring controls such as
scroll-behavior
Scrolling behavior for re-snapping to the same box as before
however, is UA-defined.
The UA may, for example,
when snapped to the start of a section,
choose not to animate the scroll to the section’s new position
as content is dynamically added earlier in the document
in order to create the illusion of not scrolling.
In the following example,
the log console,
when initially loaded and as each message is added to the bottom,
remains snapped to the bottom of the content
unless the user has scrolled away from that edge:
.log
scroll-snap-type
y proximity
align-content
end
.log::after
display
block
content
""
scroll-snap-align
end
The rules create a single
scroll snap area
represented by the
::after
pseudo-element,
positioned at the very bottom of a
scroll snap container
If the user scrolls “near” the bottom,
the container will snap to it.
If more content is dynamically added to the container,
it’ll remain snapped to it
(because scroll containers are required
to re-snap to the same scroll snap area
if it still exists after any changes).
However, if the user has scrolled to somewhere else in the logs,
it won’t do anything at all.
4.2.
Scroll Snapport: the
scroll-padding
property
Name:
scroll-padding
Value:
[ auto

{1,4}
Initial:
auto
Applies to:
scroll containers
Inherited:
no
Percentages:
relative to the corresponding dimension of the scroll container’s scrollport
Computed value:
per side, either the keyword
auto
or a computed

value
Animation type:
by computed value type
Canonical order:
per grammar
This property specifies
(for all
scroll containers
, not just
scroll snap containers
offsets that define the
optimal viewing region
of a scrollport:
the region used as the target region for placing things in view of the user.
This allows the author to exclude regions of the
scrollport
that are obscured by other content
(such as fixed-positioned toolbars or sidebars)
or simply to put more breathing room
between a targeted element and the edges of the scrollport.
The
scroll-padding
property is a
shorthand property
that sets
all of the
scroll-padding-*
longhands
in one declaration,
assigning values to the longhands representing each side
exactly as the
padding
property does for its longhands.
Values have the following meanings:

Defines an inward offset from the corresponding edge of the
scrollport
When applied to the root viewport,
the offset is calculated and applied relative to the layout viewport
(rather than the visual viewport)
the same way as the corresponding
inset properties
on
fixed-positioned boxes
the
optimal viewing region
is the remaining area
that intersects with the visual viewport.
auto
Indicates that the offset for the corresponding edge of the
scrollport
is UA-determined.
This should generally default to a used length of
0px
but UAs may use heuristics to detect when a non-zero value is more appropriate.
For example, a UA could detect when a
position:fixed
element
is being used as an opaque unscrollable “header”
that obscures the content below it,
and resolve the top offset to the height of that element
so that a “page down” operation (such as pressing
PgDn
automatically scrolls by one “visible page” of content.
These offsets reduce the region of the
scrollport
that is considered “viewable”
for scrolling operations
they have no effect on layout,
on the scroll origin or initial position,
or on whether or not an element is considered actually
visible
but should
affect whether an element or the caret is considered scrolled into view
(e.g. for targeting or focusing operations),
and reduce the amount of scrolling for paging operations
(such as using the
PgUp
and
PgDn
keys
or triggering equivalent operations from the scrollbar)
so that within the
optimal viewing region
of the
scrollport
the user sees a continuous stream of content.
For a
scroll snap container
this region also defines
the
scroll snapport
—​the area of the scrollport that is used as the
alignment container
for the
scroll snap areas
when calculating
snap positions
In this example,
scroll-padding
is used to center slideshow images
within the portion of the scrollport
that is not obscured by a fixed-position toolbar.
html
overflow-x
auto
overflow-y
hidden
scroll-snap-type
x mandatory
scroll-padding
500
px
.toolbar
position
fixed
height
100
width
500
px
right
img
scroll-snap-align
none center
UAs must apply the
scroll-padding
values set on the root element
to the document viewport.
(Note that, unlike
overflow
scroll-padding
values are
not
propagated from HTML
body
.)
5.
Aligning Scroll Snap Areas: Properties on the elements
5.1.
Scroll Snapping Area: the
scroll-margin
property
Name:
scroll-margin
Value:

{1,4}
Initial:
Applies to:
all elements
Inherited:
no
Percentages:
n/a
Computed value:
per side, an absolute length
Canonical order:
per grammar
Animation type:
by computed value type
This property is a
shorthand property
that sets
all of the
scroll-margin-*
longhands
in one declaration,
assigning values to the longhands representing each side
exactly as the
margin
property does for its longhands.
Values represent outsets defining the
scroll snap area
that is used for snapping this box to the snapport.
The
scroll snap area
is determined by taking the transformed border box,
finding its rectangular bounding box
(axis-aligned in the
scroll container’s
coordinate space),
then adding the specified outsets.
Note:
This ensures that the
scroll snap area
is always rectangular
and axis-aligned to the
scroll container’s
coordinate space.
If a page is navigated to a fragment that defines a target element
(one that would be matched by
:target
or the target of
scrollIntoView()
),
the UA should use the element’s
scroll snap area
rather than just its border box,
to determine which area of the
scrollable overflow area
to bring into view,
even when snapping is off
or not applied on this element
5.2.
Scroll Snapping Alignment: the
scroll-snap-align
property
Name:
scroll-snap-align
Value:
[ none
start
end
center ]
{1,2}
Initial:
none
Applies to:
all elements
Inherited:
no
Percentages:
n/a
Computed value:
two keywords
Canonical order:
per grammar
Animation type:
discrete
The
scroll-snap-align
property specifies
the box’s
snap position
as an alignment of
its
snap area
(as the
alignment subject
within its
snap container’s
snapport
(as the
alignment container
).
The two values specify the snapping alignment
in the
block axis
and
inline axis
, respectively,
as determined by the
snap container
’s
writing mode
If only one value is specified, the second value defaults to the same value.
Values are defined as follows:
none
This box does not define a
snap position
in the specified axis.
start
Start alignment of this box’s
scroll snap area
within the
scroll container
’s
snapport
is a
snap position
in the specified axis.
end
End alignment of this box’s
scroll snap area
within the
scroll container
’s
snapport
is a
snap position
in the specified axis.
center
Center alignment of this box’s
scroll snap area
within the
scroll container
’s
snapport
is a
snap position
in the specified axis.
Start and end alignments are resolved
with respect to the
writing mode
of the
snap container
unless the
scroll snap area
is larger than the
snapport
in which case they are resolved with respect to the
writing mode
of the box itself.
(This allows items in a container to have consistent snap alignment in general,
while ensuring that
start
always aligns the item
to allow reading its contents from the beginning.)
5.2.1.
Scoping Valid Snap Positions to Visible Boxes
Since the purpose of scroll snapping is to align content within the
scrollport
for optimal viewing,
a scroll position cannot be considered a valid
snap position
if
snapping
to it would leave the contributing
snap area
entirely outside the
snapport
even if it otherwise satisfies the required alignment of the
snap area
For example, a
snap area
is top-aligned to the
snapport
if its top edge is coincident with the
snapport
’s top edge;
and this would be considered a valid
snap position
for block-axis start-aligned snapping of that
snap area
if at least part of the
snap area
is on-screen
If the entire
snap area
is outside the
snapport
, however,
then the
scroll container
cannot be considered to be
snapped
because the required alignment, though satisfied, would not be relevant to the viewer.
╔════viewport════╗┈┈┈┈┈┈┈┈┌──────────────┐
║ ┌─────┐ ┌──┐ ║ │ top-snapping │
║ ├──┐ │ └──┘ ║ │ element │
║ └──┴──┘ ║ │ │
╚════════════════╝ │ │
└──────────────┘
Alignment of an off-screen element
is not considered
snapping
Why limit snapping to only when the element is visible?
As the
WebKit implementers point out
extending a snap edge infinitely across the canvas
only allows for snapping gridded layouts,
and produces odd behavior for the user
when off-screen elements do not align
with on-screen elements.
(If this requirement is onerous for implementers however,
we can default to a gridded behavior
and introduce a switch to get smarter behavior later.)
Note:
Although
scroll-snap-type: both
evaluates
snap positions
independently in each axis,
choosing
of a
snap position
in one axis
can be influenced by
snap positions
in the other axis.
For example, snapping in one axis
may push off-screen the
snap area
that the other axis would otherwise align to,
making its
snap position
invalid and therefore unchooseable.
5.2.2.
Snapping Boxes that Overflow the Scrollport
If the
snap area
is larger than the
snapport
in a particular axis,
then any scroll position in which
the
snap area
covers the
snapport
, and
the distance between the geometrically previous and subsequent
otherwise-valid
snap positions
in that axis
is larger than size of the
snapport
in that axis,
is a valid
snap position
in that axis.
The UA may use the specified alignment as a more precise target
for certain scroll operations (e.g. explicit paging).
For example, take the first example in
§ 2 Motivating Examples
which had a photo as the area.
The author wants mandatory snapping from item to item,
but if the item happens to be larger than your viewport,
you want to be able to scroll around the whole thing once you’re over it.
Since the
snap area
is larger than the
snapport
while the area fully fills the viewport,
the container can be scrolled arbitrarily
and will not try to snap back to its aligned position.
However, if the container is scrolled such that the area
no longer fully fills the viewport in an axis,
the area resists outward scrolling
until it is scrolled sufficiently
to trigger snapping to a different
snap position
For another example,
mandatory top-snapping on nested
section
elements
can produce large snapping areas
(from large top-level sections)
potentially filled with smaller snapping areas
(from the subsections).
When the subsections are small enough,
they snap normally;
when they’re longer,
the viewer can scroll arbitrarily within them,
or within a large segment of the top-level section that has no subsections to snap to.
┌─ top-level section ─┐ ━┓ ┳ 1 (scroll position = 0)
│ │ 1┃ ┃
│ │ ┃ ┃
│ │ ━┩ ┃
│ │ ┆ ╿
│ │ ┆ │
│ │ ┆ │
│┌─── sub-section ───┐│ ╯ ━┓ ┿ 2
│└───────────────────┘│ 2┃ │
│┌─── sub-section ───┐│ ━┓ ┃ ┿ 3
││ ││ 3┃ ━┛ │
│└───────────────────┘│ ┃ │
│┌─── sub-section ───┐│ ━┛ ━┓ ┿ 4
│└───────────────────┘│ 4┃ │
│┌─── sub-section ───┐│ ━┓ ┃ ╈ 5
││ ││ 5┃ ━┛ ┃
││ ││ ┃ ┃
││ ││ ━┩ ┃
││ ││ ┆ ┃
││ ││ ┆ ╹
││ ││ ┆
│└───────────────────┘│ ┆
└─────────────────────┘ ╯
In the figure above,
the five numbered viewports
represent the five snap positions
associated with the top-level section
and its four subsections.
Because the first and last snap positions are part of ranges taller than the viewport,
the viewer is allowed to scroll freely
between the top and bottom of each range.
Any position in that range is a valid
snap position
which can be snapped to when it is the nearest position;
however, if the element is targetted directly
(such as by a fragment ID or a scrolling API),
the UA will land on the bolded position,
which corresponds to the ideal requested alignment
of the element’s
snap area
within the
snapport
Note:
If the author had instead set mandatory snap positions
on the
headings
of each section
(rather than the sections themselves),
the contents of the first and fifth sections
would be partially inaccessible to the user,
as the heading snap area does not extend to cover the whole section.
This is why it’s a bad idea to use mandatory snap positions
on elements that might be widely spaced apart.
5.2.3.
Unreachable Snap Positions
If a
snap position
is unreachable as specified,
such that aligning to it would require scrolling the
scroll container
’s viewport
past the edge of its
scrollable overflow area
the
used
snap position
for this
snap area
is the position resulting from scrolling
as much as possible
in each relevant axis
toward the desired
snap position
5.3.
Scroll Snap Limits: the
scroll-snap-stop
property
Name:
scroll-snap-stop
Value:
normal
always
Initial:
normal
Applies to:
all elements
Inherited:
no
Percentages:
n/a
Computed value:
specified keyword
Canonical order:
per grammar
Animation type:
discrete
When performing a
relative scroll
the
scroll container
can “pass over” several possible
snap positions
(that would be valid to snap to,
if the scrolling operation used the same direction
but a lesser distance)
before reaching the natural endpoint of the scroll operation
and selecting its final
scroll position
The
scroll-snap-stop
property allows such a possible
snap position
to “trap” the scrolling operation,
forcing the
scroll container
to stop
before the scrolling operation would naturally end.
Values are defined as follows:
normal
The
scroll container
may pass over a
snap position
defined
by this element during the execution of a scrolling operation.
always
The
scroll container
must not pass over a
snap position
defined by this element during the execution of a scrolling operation;
it must instead snap to the first of this element’s
snap positions
This property has no effect on non-
relative scrolling
operations,
as they do not conceptually “pass over” any
snap positions
6.
Snapping Mechanics
The precise model algorithm to select a
snap position
to snap to
is intentionally left mostly undefined,
so that user agents can take into account sophisticated models of user intention and interaction
and adjust how they respond over time,
to best serve the user.
This section defines some useful concepts to aid in discussing scroll-snapping mechanics,
and provides some guidelines for what an effective scroll-snapping strategy might look like.
User agents are encouraged to adapt this guidance
and apply their own best judgement
when defining their own snapping behavior.
It also provides a small number of behavior requirements,
to ensure a minimum reasonable behavior that authors can depend on
when designing their interfaces with scroll-snapping in mind.
6.1.
Types of Scrolling Methods
There are many ways to cause a page to scroll,
and they differ in their intent,
which affects how scroll snapping and other features
should
respond
to them.
The types of scrolling intents are:
absolute scroll
An
absolute scroll
is a scrolling operation
that is not intended to have any relation with the previous scroll position.
Whether the new position is before or after the previous scroll position
is not relevant to the operation;
the scroll container just "goes straight there".
Common examples of
absolute scrolls
include:
manipulating the scrollbar “thumb” explicitly
programmatically scrolling via APIs such as
scrollTo()
tabbing through the document’s focusable elements
navigating to an anchor within the page
homing operations such as the
End
keys
Note:
Scroll snapping responds to an
absolute scroll
by finding the nearest valid
snap position
regardless
of direction.
relative scroll
relative scroll
is a scrolling operation
that does have a meaningful relation with the previous scroll position;
that is, the fact that the new scroll position is before or after the old scroll position
is an important quality of the scroll.
Relative scrolls might or might not have an intended end position,
but they always have an intended
direction
Common examples of
relative scrolls
with both an intended direction and end position include:
a “fling” gesture, interpreted with momentum
a panning gesture,
released with or without momentum
programmatically scrolling via APIs such as
scrollBy()
paging operations such as the
PgUp
PgDn
keys (or equivalent operations on the scrollbar)
Common examples of
relative scrolls
with only an intended direction include:
pressing an arrow key on the keyboard
pressing an arrow button on the scrollbar
a swiping gesture interpreted as a fixed (rather than inertial) scroll
The intended end point of the scroll prior to intervention from features such
as snap points is its
natural end-point
Note:
Scroll snapping responds to a
relative scroll
by finding the nearest valid
snap position
in the intended direction
(if possible),
so a snapped element can’t get "trapped"
when the
snap positions
are far apart.
stationary scroll
stationary scroll
is a scrolling operation
that isn’t "intending" to move the scroller at all;
instead, it’s attempting to keep something stationary
(usually, an element you’re focusing on).
Common examples of
stationary scrolls
include:
scroll anchoring with
overflow-anchor
when off-screen content changes size
and would move the current anchor
scroll snapping (especially
mandatory
when another element changes size
and causes the scroller to no longer be at a valid snap point
Note:
Scroll snapping responds to a
stationary scroll
by finding the nearest valid
snap position
similar to an
absolute scroll
Additionally, because page layouts usually align things vertically and/or horizontally,
UAs sometimes
axis-lock
a scroll when its direction
is sufficiently vertical or horizontal.
An
axis-locked
scroll is bound to only scroll along that axis.
This prevents less-precise input mechanisms from drifting in the non-primary axis.
Note:
This specification only applies to scrolling methods supported by the user agent;
it does not require the user agent to support any particular input or scrolling method.
6.2.
Choosing Snap Positions
scroll container
can have many
snap areas
scattered throughout its
scrollable overflow area
A naïve algorithm for selecting a
snap position
can produce behavior that is unintuitive for users,
so care is required when designing a selection algorithm.
Here are a few pointers that can aid in the selection process:
Snap positions
should be chosen to minimize the distance between the end-point
(or the
natural end-point
and the final snapped scroll position,
subject to the additional constraints listed in this section.
If a scroll is
axis-locked
any
snap positions
in the other axis should be ignored
during the scroll.
(However,
snap positions
in the other axis can still effect the final scroll position.)
In order to prevent a far-offscreen element
from having difficult-to-understand effects
on the scroll position,
snap positions
should be ignored if their elements are far outside of the “corridor”
that the
snapport
defines as it moves through the
scrollable overflow area
or a hypothetical “corridor” in the direction of a
relative scroll
or the
snapport
after an
absolute scroll
User agents
must
ensure that a user can “escape” a
snap position
regardless of the scroll method.
For example, if the snap type is
mandatory
and the next
snap position
is more than two screen-widths away,
a naïve “always snap to nearest” selection algorithm might “trap” the user
if their end position was only one screen-width away.
Instead, a smarter algorithm that only returned to the starting
snap position
if the end-point was a fairly small distance from it,
and otherwise ignored the starting snap position,
would give better behavior.
(This implies that a
relative scroll
without an intended end position
must always ignore the starting
snap positions
.)
If a page is navigated to a fragment that defines a target element
(e.g. one that would be matched by
:target
or the target of
scrollIntoView()
),
and that element defines some
snap positions
the user agent must
snap
to one of that element’s
snap positions
if its nearest
scroll container
is a
scroll snap container
The user agent
may
also do this even when the
scroll container
has
scroll-snap-type: none
If a scroll by page operation (e.g. Page down / Page up) is being performed,
eligible
snap positions
that require scrolling less than or equal to the size of the
optimal viewing region
of the
scroll container
should be selected before any farther away, ignoring the starting
snap positions
so that progress is still made in the intended direction.
6.2.1.
Selecting between multiple aligned snap areas
When
snapping
to a scroll position
that is aligned with multiple
scroll snap areas
the following algorithm procedure is used to determined which box is
snapped
on the block and inline axes
for a particular
scroll container
Let
scroll position
be the scroll position of the
scroll container
Let
inline
be the set of boxes whose
scroll snap areas
are aligned at this
scroll position
in the inline axis.
Let
block
be the set of boxes whose
scroll snap areas
are aligned at this
scroll position
in the block axis.
For each
list
of
block
and
inline
If
list
contains the focused box, remove all other boxes from
list
If
list
contains the targeted box, remove all other boxes from
list
For each
box
in
list
Remove any box from
list
which is an ancestor of
box
If
inline
and
block
are overlapping sets:
Replace
inline
with the intersection of
inline
and
block
Replace
block
with the intersection of
inline
and
block
Select the first element in
tree order
from
inline
as the
snapped
inline axis box.
Select the first element in
tree order
from
block
as the
snapped
block axis box.
Appendix A: Longhands
The physical and logical longhands (and their shorthands)
interact as defined in
[CSS-LOGICAL-1]
Physical Longhands for
scroll-padding
Name:
scroll-padding-top
scroll-padding-right
scroll-padding-bottom
scroll-padding-left
Value:
auto

Initial:
auto
Applies to:
scroll containers
Inherited:
no
Percentages:
relative to the scroll container’s scrollport
Computed value:
the keyword
auto
or a computed

value
Canonical order:
per grammar
Animation type:
by computed value type
Logical property group:
scroll-padding
These
longhands
of
scroll-padding
specify
the top, right, bottom, and left edges
of the
snapport
, respectively.
Negative values are invalid.
Flow-relative Longhands for
scroll-padding
Name:
scroll-padding-inline-start
scroll-padding-block-start
scroll-padding-inline-end
scroll-padding-block-end
Value:
auto

Initial:
auto
Applies to:
scroll containers
Inherited:
no
Percentages:
relative to the scroll container’s scrollport
Computed value:
the keyword
auto
or a computed

value
Canonical order:
per grammar
Animation type:
by computed value type
Logical property group:
scroll-padding
These
longhands
of
scroll-padding
specify
the block-start, inline-start, block-end, and inline-end edges
of the
snapport
, respectively.
Negative values are invalid.
Name:
scroll-padding-block
scroll-padding-inline
Value:
[ auto

{1,2}
Initial:
auto
Applies to:
scroll containers
Inherited:
no
Percentages:
relative to the scroll container’s scrollport
Computed value:
see individual properties
Animation type:
by computed value
Canonical order:
per grammar
These
shorthands
of
scroll-padding-block-start
scroll-padding-block-end
and
scroll-padding-inline-start
scroll-padding-inline-end
are
longhands
of
scroll-padding
and specify the block-axis and inline-axis edges of the
snapport
, respectively.
If two values are specified, the first gives the start value
and the second gives the end value.
If only one value is specified, the second value defaults to the same value.
Physical Longhands for
scroll-margin
Name:
scroll-margin-top
scroll-margin-right
scroll-margin-bottom
scroll-margin-left
Value:

Initial:
Applies to:
all elements
Inherited:
no
Percentages:
n/a
Computed value:
absolute length
Canonical order:
per grammar
Animation type:
by computed value type
Logical property group:
scroll-margin
These
longhands
of
scroll-margin
specify
the top, right, bottom, and left edges
of the
scroll snap area
, respectively.
Flow-relative Longhands for
scroll-margin
Name:
scroll-margin-block-start
scroll-margin-inline-start
scroll-margin-block-end
scroll-margin-inline-end
Value:

Initial:
Applies to:
all elements
Inherited:
no
Percentages:
n/a
Computed value:
absolute length
Canonical order:
per grammar
Animation type:
by computed value type
Logical property group:
scroll-margin
These
longhands
of
scroll-margin
specify the
block-start, inline-start, block-end, and inline-end edges
of the
scroll snap area
, respectively.
Name:
scroll-margin-block
scroll-margin-inline
Value:

{1,2}
Initial:
Applies to:
all elements
Inherited:
no
Percentages:
n/a
Computed value:
see individual properties
Animation type:
by computed value type
Canonical order:
per grammar
These
shorthands
of
scroll-margin-block-start
scroll-margin-block-end
and
scroll-margin-inline-start
scroll-margin-inline-end
are
longhands
of
scroll-margin
and specify the block-axis and inline-axis edges
of the
scroll snap area
, respectively.
If two values are specified, the first gives the start value
and the second gives the end value.
If only one value is specified, the second value defaults to the same value.
7.
Privacy Considerations
This specification does not expose any information whatsoever
that is not already exposed to the DOM directly;
it just makes scrolling slightly more functional.
There are no new privacy considerations.
8.
Security Considerations
This specification does not expose any information whatsoever
that is not already exposed to the DOM directly;
it just makes scrolling slightly more functional.
There are no new security considerations.
9.
Acknowledgements
Many thanks to
David Baron,
Simon Fraser,
Håkon Wium Lie,
Theresa O’Connor,
François Remy,
Majid Valpour,
and most especially Robert O’Callahan
for their proposals and recommendations,
which have been incorporated into this document.
10.
Changes
10.1.
Changes Since 19 March 2019 CR
Changes since the
19 March 2019 Candidate Recommendation
include:
Specified which writing mode is used to resolve
scroll-snap-align
Issue 3815
Define requirements for re-snapping when multiple elements coincide.
Issue 4651
If the
scroll container
was
snapped
before the content change
and that same
snap position
still exists
(e.g. its associated element was not deleted),
the scroll container must be re-snapped to that same snap position
after the content change.
If multiple boxes were
snapped
before
and their
snap positions
no longer coincide,
then if one of them is focused or targeted,
the
scroll container
must re-snap to that one
and otherwise which one to re-snap to is UA-defined.
(The UA may, for example, track which element is snapped
as layout shifts align and de-align
the
snap positions
of other elements.)
Require re-snapping to a new element to animate the same way
as any other scroll-into-view operation.
Issue 4609
Scrolling required by a re-snap operation to a new or different box
must behave and animate the same way as
any other scroll-into-view operation,
including honoring controls such as
scroll-behavior
Scrolling behavior for re-snapping to the same box as before
however, is UA-defined.
The UA may, for example,
when snapped to the start of a section,
choose not to animation the scroll to the section’s new position
as content is dynamically added earlier in the document
in order to create the illusion of not scrolling.
Defined explicitly that
scroll-snap-type
and
scroll-padding
values
are propagated from the root element to the document viewport
as would be expected.
Issue 3740
UAs must apply the
scroll-snap-type
value set on the root element
to the document viewport.
Note that, unlike
overflow
scroll-snap-type
values are
not
propagated from HTML
body
UAs must apply the
scroll-padding
values set on the root element
to the document viewport.
(Note that, unlike
overflow
scroll-padding
values are
not
propagated from HTML
body
.)
Clarified that while snap alignment is relative to the visual viewport,
scroll-padding
is resolved against the layout viewport,
so that
scroll-padding
and
inset
are consistent on the root viewport.
Issue 4393
Defines an inward offset from the corresponding edge of the
scrollport
When applied to the root viewport,
the offset is calculated and applied relative to the layout viewport
(rather than the visual viewport)
the same way as the corresponding
inset properties
on
fixed-positioned boxes
the
optimal viewing region
is the remaining area
that intersects with the visual viewport.
Corrected the “Applies to” line for
scroll-padding-inline
and
scroll-padding-block
Issue 5845
Disposition of Comments
is available.
10.2.
Changes Since 31 January 2019 CR
Changes since the
31 January 2019 Candidate Recommendation
include:
Emphasized that
scroll-padding
and
scroll-margin
do apply
even when scroll snapping is off.
Issue 3721
Also, to offer better control over paging and scroll positioning
even when snapping is off,
this module defines the
scroll-padding
property
for use on all
scroll containers
to adjust the
scroll container
’s
optimal viewing region
for the purpose of paging and scroll-into-view operations;
similarly the
scroll-margin
property can be used on any box
to adjust its visual area
for the purpose of scroll-into-view operations.
This property specifies
(for all
scroll containers
, not just
scroll snap containers
offsets that define the
optimal viewing region
of a scrollport…
If a page is navigated to a fragment that defines a target element
(one that would be matched by
:target
or the target of
scrollIntoView()
),
the UA should use the element’s
scroll snap area
rather than just its border box,
to determine which area of the
scrollable overflow area
to bring into view
even when snapping is off
or not applied on this element
10.3.
Changes Since 14 August 2018 CR
Changes since the
14 August 2018 Candidate Recommendation
include:
Corrected
scroll-padding
longhands to list the new
auto
keyword in their property definition tables.
Issue 3189
Fixed up “Computed value” and “Animation type” lines in the property definition tables.
Cleaned up stray

values in
scroll-margin
property definition tables.
3289
Disposition of Comments is available
10.4.
Changes Since 14 December 2017 CR
Changes since the
14 December 2017 Candidate Recommendation
include:
Fixed
scroll-snap-align
shorthand to assign
block-axis value first, inline-axis value second,
accordingly to logical shorthand conventions.
Issue 2232
Added
auto
keyword to 'scroll-padding as its initial value
to account for UA heuristics.
Issue 2728
Clarified in the definition of
scroll-snap-type
that programmatic scrolls such as
scrollTo()
are also subject to snapping.
Issue 2593
Using the
scroll-snap-type
property on the relevant
scroll container
the author can request a particular bias
for the scrollport to land on a
snap position
after scrolling operations
(including programmatic scrolls such as the
scrollTo()
method)
Adjusted wording in
§ 5.2.1 Scoping Valid Snap Positions to Visible Boxes
to be clearer—​compared to
old version
Issue 2526
Disposition of Comments
is available.
10.5.
Changes Since 24 August 2017 CR
Changes since the
24 August 2017 Candidate Recommendation
include:
:target
scrollIntoView()
/etc should take
scroll-margin
into account,
regardless of whether snapping is turned on or not.
Issue 1
If a page is navigated to a fragment that defines a target element
(one that would be matched by
:target
or the target of
scrollIntoView()
),
the UA should use the element’s
scroll snap area
rather than just its border box,
to determine which area of the
scrollable overflow area
to bring into view.
:target
scrollIntoView()
/etc must (rather than should)
use snap positions if snapping is turned on.
Issue 1
If a page is navigated to a fragment that defines a target element
(one that would be matched by
:target
or the target of
scrollIntoView()
),
and that element defines some
snap positions
the user agent
should
must
snap
to one of that element’s
snap positions
if its nearest
scroll container
is a
scroll snap container
The user agent
may
also do this even when
the
scroll container
has
scroll-snap-type: none
Renamed
scroll-snap-margin
to
scroll-margin
to reflect its more generic role in providing breathing space
for scrolling to an element regardless of snapping behavior.
Issue 4
Disposition of Comments
is available.
10.6.
Changes Since 20 October 2016 CR
Changes since the
20 October 2016 Candidate Recommendation
include:
Restricted
scroll-padding
to non-negative values.
Issue 1084
Values
must be non-negative and
are interpreted as for
padding
Added paging and homing operations to examples in
§ 6.1 Types of Scrolling Methods
Issue 1605
Clarified that snapping in one axis may affect whether snapping to a particular snap area is possible in the other axis.
Issue 950
Although
scroll-snap-type: both
evaluates
snap positions
independently in each axis,
choosing
of a
snap position
in one axis
may be influenced by
snap positions
in the other axis.
For example, snapping in one axis
may push off-screen the
snap area
that the other axis would otherwise align to,
making its
snap position
invalid and therefore unchooseable.
Clarified how the
scroll-padding
and
scroll-margin
shorthands
assign values to their longhands.
Issue 1050
Clarified that scroll snapping does not mandate any particular input method.
Issue 1305
This specification only applies to scrolling methods supported by the user agent;
it does not require the user agent to support any particular input or scrolling method.
Clarified the intended effects of
scroll-snap-stop
on various scrolling operations.
Issue 1552
Clarified that
scroll-snap-stop
is applied to the
snap positions
defined by the element,
not applied to all
snap positions
in the
scroll snap container
Fixed some syntax errors in examples and added a new one to the
scroll-snap-type
section.
Issue 827
Disposition of Comments
is available.
Conformance
Document conventions
Conformance requirements are expressed with a combination of
descriptive assertions and RFC 2119 terminology. The key words “MUST”,
“MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”,
“RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this
document are to be interpreted as described in RFC 2119.
However, for readability, these words do not appear in all uppercase
letters in this specification.
All of the text of this specification is normative except sections
explicitly marked as non-normative, examples, and notes.
[RFC2119]
Examples in this specification are introduced with the words “for example”
or are set apart from the normative text with
class="example"
like this:
This is an example of an informative example.
Informative notes begin with the word “Note” and are set apart from the
normative text with
class="note"
, like this:
Note, this is an informative note.
Advisements are normative sections styled to evoke special attention and are
set apart from other normative text with

, like
this:
UAs MUST provide an accessible alternative.
Tests
Tests relating to the content of this specification
may be documented in “Tests” blocks like this one.
Any such block is non-normative.
Conformance classes
Conformance to this specification
is defined for three conformance classes:
style sheet
CSS
style sheet
renderer
UA
that interprets the semantics of a style sheet and renders
documents that use them.
authoring tool
UA
that writes a style sheet.
A style sheet is conformant to this specification
if all of its statements that use syntax defined in this module are valid
according to the generic CSS grammar and the individual grammars of each
feature defined in this module.
A renderer is conformant to this specification
if, in addition to interpreting the style sheet as defined by the
appropriate specifications, it supports all the features defined
by this specification by parsing them correctly
and rendering the document accordingly. However, the inability of a
UA to correctly render a document due to limitations of the device
does not make the UA non-conformant. (For example, a UA is not
required to render color on a monochrome monitor.)
An authoring tool is conformant to this specification
if it writes style sheets that are syntactically correct according to the
generic CSS grammar and the individual grammars of each feature in
this module, and meet all other conformance requirements of style sheets
as described in this module.
Partial implementations
So that authors can exploit the forward-compatible parsing rules to
assign fallback values, CSS renderers
must
treat as invalid (and
ignore
as appropriate
) any at-rules, properties, property values, keywords,
and other syntactic constructs for which they have no usable level of
support. In particular, user agents
must not
selectively
ignore unsupported component values and honor supported values in a single
multi-value property declaration: if any value is considered invalid
(as unsupported values must be), CSS requires that the entire declaration
be ignored.
Implementations of Unstable and Proprietary Features
To avoid clashes with future stable CSS features,
the CSSWG recommends
following best practices
for the implementation of
unstable
features and
proprietary extensions
to CSS.
Non-experimental implementations
Once a specification reaches the Candidate Recommendation stage,
non-experimental implementations are possible, and implementors should
release an unprefixed implementation of any CR-level feature they
can demonstrate to be correctly implemented according to spec.
To establish and maintain the interoperability of CSS across
implementations, the CSS Working Group requests that non-experimental
CSS renderers submit an implementation report (and, if necessary, the
testcases used for that implementation report) to the W3C before
releasing an unprefixed implementation of any CSS features. Testcases
submitted to W3C are subject to review and correction by the CSS
Working Group.
Further information on submitting testcases and implementation reports
can be found from on the CSS Working Group’s website at
Questions should be directed to the
public-css-testsuite@w3.org
mailing list.
Index
Terms defined by this specification
absolute scroll
, in § 6.1
always
, in § 5.3
auto
, in § 4.2
axis-lock
, in § 6.1
axis value
, in § 4.1.1
block
, in § 4.1.1
both
, in § 4.1.1
captures snap positions
, in § 4.1.2
center
, in § 5.2
end
, in § 5.2
inline
, in § 4.1.1

, in § 4.2
mandatory
, in § 4.1.2
natural end-point
, in § 6.1
none
value for scroll-snap-align
, in § 5.2
value for scroll-snap-type
, in § 4.1.2
normal
, in § 5.3
optimal viewing region
, in § 4.2
proximity
, in § 4.1.2
relative scroll
, in § 6.1
re-snap
, in § 4.1.2
scroll-margin
, in § 5.1
scroll-margin-block
, in § Unnumbered section
scroll-margin-block-end
, in § Unnumbered section
scroll-margin-block-start
, in § Unnumbered section
scroll-margin-bottom
, in § Unnumbered section
scroll-margin-inline
, in § Unnumbered section
scroll-margin-inline-end
, in § Unnumbered section
scroll-margin-inline-start
, in § Unnumbered section
scroll-margin-left
, in § Unnumbered section
scroll-margin-right
, in § Unnumbered section
scroll-margin-top
, in § Unnumbered section
scroll-padding
, in § 4.2
scroll-padding-block
, in § Unnumbered section
scroll-padding-block-end
, in § Unnumbered section
scroll-padding-block-start
, in § Unnumbered section
scroll-padding-bottom
, in § Unnumbered section
scroll-padding-inline
, in § Unnumbered section
scroll-padding-inline-end
, in § Unnumbered section
scroll-padding-inline-start
, in § Unnumbered section
scroll-padding-left
, in § Unnumbered section
scroll-padding-right
, in § Unnumbered section
scroll-padding-top
, in § Unnumbered section
scroll snap
, in § 3
scroll-snap-align
, in § 5.2
scroll snap area
, in § 5.1
scroll snap container
, in § 4.1.2
scroll snapport
, in § 4.2
scroll snap position
, in § 3
scroll-snap-stop
, in § 5.3
scroll-snap-type
, in § 4.1
snap
, in § 3
snap area
, in § 5.1
snap container
, in § 4.1.2
snapport
, in § 4.2
snap position
, in § 3
start
, in § 5.2
stationary scroll
, in § 6.1
strictness value
, in § 4.1.2
, in § 4.1.1
, in § 4.1.1
Terms defined by reference
[CSS-ALIGN-3]
defines the following terms:
alignment container
alignment subject
[CSS-BOX-4]
defines the following terms:
margin
padding
[CSS-CASCADE-5]
defines the following terms:
longhand
shorthand
shorthand property
[CSS-DISPLAY-4]
defines the following terms:
containing block chain
[CSS-LOGICAL-1]
defines the following terms:
inset properties
[CSS-OVERFLOW-3]
defines the following terms:
overflow
scroll container
scroll position
scroll-behavior
scrollable overflow area
scrollport
[CSS-POSITION-3]
defines the following terms:
fixed-positioned box
inset
[CSS-PSEUDO-4]
defines the following terms:
::after
::first-letter
::first-line
[CSS-SCROLL-ANCHORING-1]
defines the following terms:
overflow-anchor
[CSS-VALUES-4]
defines the following terms:



CSS-wide keywords
{A,B}
[CSS-WRITING-MODES-4]
defines the following terms:
block axis
inline axis
writing mode
[CSSOM-VIEW-1]
defines the following terms:
scrollBy()
scrollIntoView()
scrollTo()
[DOM]
defines the following terms:
tree order
[HTML]
defines the following terms:
body
section
[SELECTORS-4]
defines the following terms:
:target
References
Normative References
[CSS-ALIGN-3]
Elika Etemad; Tab Atkins Jr..
CSS Box Alignment Module Level 3
. URL:
[CSS-BOX-4]
Elika Etemad.
CSS Box Model Module Level 4
. URL:
[CSS-CASCADE-5]
Elika Etemad; Miriam Suzanne; Tab Atkins Jr..
CSS Cascading and Inheritance Level 5
. URL:
[CSS-DISPLAY-4]
Elika Etemad; Tab Atkins Jr..
CSS Display Module Level 4
. URL:
[CSS-LOGICAL-1]
Elika Etemad; Rossen Atanassov.
CSS Logical Properties and Values Module Level 1
. URL:
[CSS-OVERFLOW-3]
Elika Etemad; Florian Rivoal.
CSS Overflow Module Level 3
. URL:
[CSS-POSITION-3]
Elika Etemad; Tab Atkins Jr..
CSS Positioned Layout Module Level 3
. URL:
[CSS-PSEUDO-4]
Elika Etemad; Alan Stearns.
CSS Pseudo-Elements Module Level 4
. URL:
[CSS-VALUES-3]
Tab Atkins Jr.; Elika Etemad.
CSS Values and Units Module Level 3
. URL:
[CSS-VALUES-4]
Tab Atkins Jr.; Elika Etemad.
CSS Values and Units Module Level 4
. URL:
[CSS-WRITING-MODES-4]
Elika Etemad; Koji Ishii.
CSS Writing Modes Level 4
. URL:
[CSS2]
Bert Bos; et al.
Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification
. URL:
[CSSOM-VIEW-1]
Simon Fraser; Emilio Cobos Álvarez.
CSSOM View Module
. URL:
[DOM]
Anne van Kesteren.
DOM Standard
. Living Standard. URL:
[HTML]
Anne van Kesteren; et al.
HTML Standard
. Living Standard. URL:
[RFC2119]
S. Bradner.
Key words for use in RFCs to Indicate Requirement Levels
. March 1997. Best Current Practice. URL:
[SELECTORS-4]
Elika Etemad; Tab Atkins Jr..
Selectors Level 4
. URL:
Non-Normative References
[CSS-SCROLL-ANCHORING-1]
Tab Atkins Jr..
CSS Scroll Anchoring Module Level 1
. URL:
Property Index
Name
Value
Initial
Applies to
Inh.
%ages
Anim­ation type
Canonical order
Com­puted value
Logical property group
scroll-margin
{1,4}
all elements
no
n/a
by computed value type
per grammar
per side, an absolute length
scroll-margin-block
{1,2}
all elements
no
n/a
by computed value type
per grammar
see individual properties
scroll-margin-block-end

all elements
no
n/a
by computed value type
per grammar
absolute length
scroll-margin
scroll-margin-block-start

all elements
no
n/a
by computed value type
per grammar
absolute length
scroll-margin
scroll-margin-bottom

all elements
no
n/a
by computed value type
per grammar
absolute length
scroll-margin
scroll-margin-inline
{1,2}
all elements
no
n/a
by computed value type
per grammar
see individual properties
scroll-margin-inline-end

all elements
no
n/a
by computed value type
per grammar
absolute length
scroll-margin
scroll-margin-inline-start

all elements
no
n/a
by computed value type
per grammar
absolute length
scroll-margin
scroll-margin-left

all elements
no
n/a
by computed value type
per grammar
absolute length
scroll-margin
scroll-margin-right

all elements
no
n/a
by computed value type
per grammar
absolute length
scroll-margin
scroll-margin-top

all elements
no
n/a
by computed value type
per grammar
absolute length
scroll-margin
scroll-padding
[ auto | ]{1,4}
auto
scroll containers
no
relative to the corresponding dimension of the scroll container’s scrollport
by computed value type
per grammar
per side, either the keyword auto or a computed value
scroll-padding-block
[ auto | ]{1,2}
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value
per grammar
see individual properties
scroll-padding-block-end
auto |
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value type
per grammar
the keyword auto or a computed value
scroll-padding
scroll-padding-block-start
auto |
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value type
per grammar
the keyword auto or a computed value
scroll-padding
scroll-padding-bottom
auto |
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value type
per grammar
the keyword auto or a computed value
scroll-padding
scroll-padding-inline
[ auto | ]{1,2}
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value
per grammar
see individual properties
scroll-padding-inline-end
auto |
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value type
per grammar
the keyword auto or a computed value
scroll-padding
scroll-padding-inline-start
auto |
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value type
per grammar
the keyword auto or a computed value
scroll-padding
scroll-padding-left
auto |
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value type
per grammar
the keyword auto or a computed value
scroll-padding
scroll-padding-right
auto |
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value type
per grammar
the keyword auto or a computed value
scroll-padding
scroll-padding-top
auto |
auto
scroll containers
no
relative to the scroll container’s scrollport
by computed value type
per grammar
the keyword auto or a computed value
scroll-padding
scroll-snap-align
[ none | start | end | center ]{1,2}
none
all elements
no
n/a
discrete
per grammar
two keywords
scroll-snap-stop
normal | always
normal
all elements
no
n/a
discrete
per grammar
specified keyword
scroll-snap-type
none | [ x | y | block | inline | both ] [ mandatory | proximity ]?
none
all elements
no
n/a
discrete
per grammar
specified keyword(s)
MDN
scroll-margin-block-end
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-margin-block-start
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-margin-inline-end
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-margin-inline-start
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-margin-block
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-margin-bottom
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
14.5+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-margin-left
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
14.5+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-margin-right
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
14.5+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-margin-top
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
14.5+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-margin-inline
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-margin
In all current engines.
Firefox
90+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
14.5+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-padding-block-end
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-padding-block-start
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-padding-inline-end
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-padding-inline-start
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-padding-block
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-padding-bottom
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-padding-left
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-padding-right
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
scroll-padding-top
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-padding-inline
In all current engines.
Firefox
68+
Safari
15+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-padding
In all current engines.
Firefox
68+
Safari
14.1+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-snap-align
In all current engines.
Firefox
68+
Safari
11+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-snap-stop
In all current engines.
Firefox
103+
Safari
15+
Chrome
75+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
scroll-snap-type
In all current engines.
Firefox
99+
Safari
11+
Chrome
69+
Opera
Edge
79+
Edge (Legacy)
None
IE
None
Firefox for Android
68+
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile