fix: restore [Source] link positioning after Redocly 0.131.0 upgrade

Redocly 0.131.0 changed CommonMark parsing so [[Source]] on its own line
after a heading is emitted as a separate <p> instead of inline inside <h1>.
That <p> collapsed to zero height (floated child), causing the [Source] link
to bleed into the description paragraph below.

Fix via overflow:hidden on the <p> containing the [Source] link, which
creates a block formatting context and makes the paragraph contain its
floated child properly. No markdown files need to change.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

styles/_content.scss

@@ -87,6 +87,15 @@
     padding-left: 20px;
   }
 
+  // [[Source]] renders as its own <p> after the heading (Redocly 0.131.0+).
+  // overflow: hidden creates a block formatting context so the <p> contains
+  // its floated child instead of collapsing to zero height and bleeding into
+  // the next paragraph.
+  p:has(> a[title="Source"]),
+  p:has(> a[title="ソース"]) {
+    overflow: hidden;
+  }
+
   // Make "invisible" headers take up no space either, so we can use them
   // to add additional anchors (e.g. for translated pages)
   h1.invisible,