[css-scroll-snap] Swap order of strictness and axis sections and add subheadings. This keeps related sections together (the mandatory-snapping warning and resnapping requirements together with capturing rules) and also puts the required parameter first.

Author: fantasai

css-scroll-snap/Overview.bs

@@ -255,41 +255,12 @@ Scroll Snapping Rules: the 'scroll-snap-type' property {#scroll-snap-type}
 
     The 'scroll-snap-type' property specifies
     whether a <a>scroll container</a> is a <a>scroll snap container</a>,
-    how strictly it <a>snaps</a>,
-    and which axes are considered.
-
-    The <dfn noexport lt="strictness value">strictness values</dfn>
-    (''scroll-snap-type/none'', ''proximity'', ''mandatory'')
-    specify how strictly
-    <a>snap positions</a> are enforced on the <a>scroll container</a>
-    (by forcing an adjustment to the scroll position).
+    how <a href="#snap-strictness">strictly</a> it <a>snaps</a>,
+    and <a href="#snap-axis">which axes</a> are considered.
     If no strictness value is specified, ''proximity'' is assumed.
-    Values are defined as follows:
-
-    <dl dfn-type="value" dfn-for="scroll-snap-type">
-        <dt><dfn>none</dfn>
-        <dd>
-            If specified on a <a>scroll container</a>, the <a>scroll container</a> must not <a>snap</a>.
-
-        <dt><dfn>mandatory</dfn>
-        <dd>
-            If specified on a <a>scroll container</a>, the <a>scroll container</a> is required to be <a>snapped</a> to a snap position when there are no active scrolling operations.  If a reachable snap position exists then the scroll container must <a>snap</a> at the termination of a scroll (if none exist then no <a>snapping</a> occurs).
 
-
-        <dt><dfn>proximity</dfn>
-        <dd>
-            If specified on a <a>scroll container</a>, the <a>scroll container</a> may <a>snap</a> to a snap position at the termination of a scroll, at the discretion of the UA given the parameters of the scroll.
-    </dl>
-
-    A box <dfn export>captures snap positions</dfn>
-    if it is a <a>scroll container</a>
-    <em>or</em> has a value other than ''scroll-snap-type/none'' for 'scroll-snap-type'.
-    If a box’s nearest <a lt="captures snap positions">snap-position capturing</a> ancestor
-    on its <a>containing block chain</a>
-    is a <a>scroll container</a> with a non-''scroll-snap-type/none'' value for 'scroll-snap-type',
-    that is the box’s <dfn export local-lt="snap container">scroll snap container</dfn>.
-    Otherwise, the box has no <a>scroll snap container</a>,
-    and its <a>snap positions</a> do not trigger <a>snapping</a>.
+<h4 id="snap-axis">
+Scroll Snap Axis: the ''x'', ''y'', ''block'', ''inline'', and ''both'' values</h4>
 
     The <dfn noexport lt="axis value">axis values</dfn>
     specify what axis(es) are affected by <a>snap positions</a>,
@@ -325,6 +296,31 @@ Scroll Snapping Rules: the 'scroll-snap-type' property {#scroll-snap-type}
             (potentially snapping to different elements in each axis).
     </dl>
 
+<h4 id="snap-strictness">
+Scroll Snap Strictness: the ''scroll-snap-type/none'', ''proximity'', and ''mandatory'' values</h4>
+
+    The <dfn noexport lt="strictness value">strictness values</dfn>
+    (''scroll-snap-type/none'', ''proximity'', ''mandatory'')
+    specify how strictly
+    <a>snap positions</a> are enforced on the <a>scroll container</a>
+    (by forcing an adjustment to the scroll position).
+    Values are defined as follows:
+
+    <dl dfn-type="value" dfn-for="scroll-snap-type">
+        <dt><dfn>none</dfn>
+        <dd>
+            If specified on a <a>scroll container</a>, the <a>scroll container</a> must not <a>snap</a>.
+
+        <dt><dfn>mandatory</dfn>
+        <dd>
+            If specified on a <a>scroll container</a>, the <a>scroll container</a> is required to be <a>snapped</a> to a snap position when there are no active scrolling operations.  If a reachable snap position exists then the scroll container must <a>snap</a> at the termination of a scroll (if none exist then no <a>snapping</a> occurs).
+
+
+        <dt><dfn>proximity</dfn>
+        <dd>
+            If specified on a <a>scroll container</a>, the <a>scroll container</a> may <a>snap</a> to a snap position at the termination of a scroll, at the discretion of the UA given the parameters of the scroll.
+    </dl>
+
     Advisement:
     Authors should use mandatory snap positions with consideration of
     varyingly-sized screens and (if applicable) varying-sized content.
@@ -334,7 +330,16 @@ Scroll Snapping Rules: the 'scroll-snap-type' property {#scroll-snap-type}
     content in between can become inaccessible
     in cases where it is longer than the screen.
 
-    <!-- mandatory and proximity -->
+    A box <dfn export>captures snap positions</dfn>
+    if it is a <a>scroll container</a>
+    <em>or</em> has a value other than ''scroll-snap-type/none'' for 'scroll-snap-type'.
+    If a box’s nearest <a lt="captures snap positions">snap-position capturing</a> ancestor
+    on its <a>containing block chain</a>
+    is a <a>scroll container</a> with a non-''scroll-snap-type/none'' value for 'scroll-snap-type',
+    that is the box’s <dfn export local-lt="snap container">scroll snap container</dfn>.
+    Otherwise, the box has no <a>scroll snap container</a>,
+    and its <a>snap positions</a> do not trigger <a>snapping</a>.
+
     If the content or layout of the document changes
     (e.g. content is added, moved, deleted, resized)
     such that the content of the <a>snapport</a> changes,