Fix markdown frontmatter rendering (#34102)

Fix #34101

web_src/css/markup/content.css

@@ -511,6 +511,18 @@
   padding-left: 2em;
 }
 
+.markup details.frontmatter-content summary {
+  text-overflow: ellipsis;
+  overflow: hidden;
+  white-space: nowrap;
+  margin-bottom: 0.25em;
+}
+
+.markup details.frontmatter-content svg {
+  vertical-align: middle;
+  margin: 0 0.25em;
+}
+
 .file-revisions-btn {
   display: block;
   float: left;