Added/modified common stylesheets

- Added a generalized diff-body class
- Added a generalized versions stylesheet

app/javascript/src/styles/common/diffs.scss

@@ -39,3 +39,19 @@
     color: var(--diff-list-obsolete-removed-color);
   }
 }
+
+.diff-body {
+  del {
+    background: var(--wiki-page-versions-diff-del-background);
+    text-decoration: none;
+  }
+
+  ins {
+    background: var(--wiki-page-versions-diff-ins-background);
+    text-decoration: none;
+  }
+
+  span.paragraph-mark {
+    opacity: 0.25;
+  }
+}

app/javascript/src/styles/common/versions.scss

@@ -0,0 +1,13 @@
+body.a-index {
+  div#p-revert-listing {
+    display: flex;
+
+    table.striped {
+      flex: 1; 
+    }
+  }
+
+  div#p-revert-listing  > article.post-preview {
+    margin-top: 2em;
+  }
+}