adding info on unimplemented parts of footnotes

Author: howcome

css-gcpm/Overview.src.html

@@ -900,7 +900,7 @@ <h2>Footnotes</h2>
 <li>one new page area: ''@footnote''
 <li>two new pseudo-elements: ''::footnote-call'' and ''::footnote-marker''
 <li>one predefined counter: ''footnote''
-<li>one new value on the 'content' property: ''target-pull()''
+<li class=unimplemented>one new value on the 'content' property: ''target-pull()''
 <li>border segments
 <!--<li>two new 'list-style-type' values: ''super-decimal'', and symbol(...)-->
 </ul>
@@ -930,7 +930,7 @@ <h2>Footnotes</h2>
 
 </div>
 
-<div class=example>
+<div class="example unimplemented">
 
 <p>To support legacy browsers, it is often better to make a link to
 the note rather than including the text inline. This example shows how
@@ -999,6 +999,7 @@ <h3>Turning elements into footnotes</h3>
 but they inherit through their normal place in the structure of the
 document.
 
+<div class=unimplemented>
 <p>The 'display' property on footnote elements is ignored. Instead,
 the value of the 'display' property in the @footnote context
 determines if footnotes are block or inline elements.
@@ -1022,6 +1023,7 @@ <h3>Turning elements into footnotes</h3>
 </pre>
 </div>
 
+</div>
 <!--
 <p class=issue>Another way to achieve this would be to introduce different keywords for inline and block footnotes (e.g., float: footnote-inline, float: footnote-block).
 -->