[web-animations-2] Cleanup of markup formatting. (#9209)

Fix typo and formatting glitches with switch.

web-animations-2/Overview.bs

@@ -288,6 +288,7 @@ follows:
         ::  Set |previous progress| = <code>|previous current time| /
             [=end time=]</code>
     </dl>
+
 1.  Let |from finite timeline| be true if |old timeline| is not null and
     not [=monotonically increasing timeline|monotonically increasing=].
 1.  Let |to finite timeline| be true if |timeline| is not null and not
@@ -985,7 +986,7 @@ For an <a>animation effect</a>, the <dfn>inherited time</dfn> at
 a given moment is based on the first matching condition from the
 following:
 
-<div class='switch'>
+<dl class='switch'>
 
 :   If the <a>animation effect</a> has a <a>parent group</a>,
 ::  the inherited time is the <a>parent group</a>'s current
@@ -997,7 +998,7 @@ following:
 :   Otherwise,
 ::  the inherited time is <a>unresolved</a>.
 
-</div>
+</dl>
 
 The <dfn>local time</dfn> of an <a>animation effect</a> is the
 <a>animation effect</a>'s <a>inherited time</a> minus its <a
@@ -2848,7 +2849,8 @@ interface SequenceEffect : GroupEffect {
 };
 </pre>
 
-<div class="contructors">
+<div class="constructors">
+
 :   <dfn constructor for=SequenceEffect lt="SequenceEffect(children, timing)">constructor (sequence&lt;AnimationEffect&gt;? children,
     optional (unrestricted double or EffectTiming) timing)</dfn>
 ::  The meaning and handling of each of the parameters in this