Make script-insets obey their bounds, and other padding tweaks.

runtime/observatory/lib/src/elements/class_view.html

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="curly_block.html">
 <link rel="import" href="eval_box.html">
 <link rel="import" href="eval_link.html">
 <link rel="import" href="field_ref.html">
 <link rel="import" href="function_ref.html">
 <link rel="import" href="instance_ref.html">
 <link rel="import" href="library_ref.html">
 <link rel="import" href="nav_bar.html">
 <link rel="import" href="observatory_element.html">
@@ skipping 181 matching lines @@
               <template if="{{ mostRetained != null }}">
                 <template repeat="{{ most in mostRetained }}">
                   {{ most.retainedSize | formatSize }}<instance-ref ref="{{ most }}"></instance-ref><br>
                 </template>
               </template>
             </div>
           </div>
         </template>
     </div>
 
-    <hr>
-
-    <div class="content">
+    <div class="content-centered-big">
+      <hr>
       <eval-box callback="{{ eval }}"></eval-box>
+      <hr>
+      <script-inset script="{{ cls.script }}"
+                    startPos="{{ cls.tokenPos }}"
+                    endPos="{{ cls.endTokenPos }}">
+      </script-inset>
     </div>
 
-    <hr>
-    <script-inset script="{{ cls.script }}"
-                  startPos="{{ cls.tokenPos }}"
-                  endPos="{{ cls.endTokenPos }}">
-    </script-inset>
-
     <view-footer></view-footer>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="class_view.dart"></script>