[web-animations-2] Fix styling.

Author: kevers-google

web-animations-2/Overview.bs

@@ -1,16 +1,46 @@
 <style>
-.constructors::before, .members::before, .attributes::before {
+.informative-bg {
+  margin: 1.5em 0 1em;
+  padding: 1em;
+  margin-top: 1em;
+  background: #efe;
+  border: green 1px dotted;
+}
+@media (prefers-color-scheme: dark) {
+  .informative-bg {
+    background: rgba(255, 255, 255, .05);
+  }
+}
+
+div.informative-bg *:last-child {
+  margin-bottom: 0;
+}
+
+div.informative-bg p:first-child {
+  margin-top: 0;
+}
+
+div.informative-bg h2,
+div.informative-bg h3,
+div.informative-bg h4 {
+  background: none;
+}
+
+.attributes::before, .methods::before,
+.parameters::before, .exceptions::before,
+.constructors::before, .members::before {
   font: bold 100% sans-serif;
   text-align: left;
   margin: 1.33em 0px;
-  color: #005A9C;
+  color: var(--heading-text, #005A9C);
 }
 
-.constructors::before { content: 'Constructors' }
-
-.members::before { content: 'Members' }
-
 .attributes::before { content: 'Attributes' }
+.methods::before { content: 'Methods' }
+.parameters::before { content: 'Parameters' }
+.exceptions::before { content: 'Exceptions' }
+.constructors::before { content: 'Constructors' }
+.members::before { content: 'Dictionary members' }
 
 dl.switch  > [data-md] > p {
   display: inline;