[css-gcpm-3][editorial] Link fixes

Author: svgeesus

css-gcpm-3/Overview.bs

@@ -960,7 +960,7 @@ CMYK Colors section moved to <a href="https://drafts.csswg.org/css-color-5/#devi
 Styling Blank Pages section deleted
 </li>
 <li>
-Paged Presentations section moved to <a href="https://drafts.csswg.org/css-overflow-3/#paginated-overflow">CSS Overflow Module Level 3</a>.
+Paged Presentations section moved to <a href="https://drafts.csswg.org/css-overflow-3/#overflow-concepts">CSS Overflow Module Level 3</a>.
 </li>
 <li>
 Navigation Between Pages moved to <a href="http://books.spec.whatwg.org/#spatial-layout-of-pages;-@layout">WHATWG CSS Books</a>
@@ -992,14 +992,14 @@ target-pull() value of content property removed
 
 </ul>
 
-<p>Differences with the <a href="http://books.spec.whatwg.org/">WHATWG CSS Books</a> specification:</p>
+<p>Differences with the <a href="http://books.ideas.whatwg.org/">WHATWG CSS Books</a> specification:</p>
 <ul>
   <li>Added ''attr(&lt;identifier>)'' value to 'string-set' property. This is supported by both Prince and AntennaHouse.</li>
 
 <li>
-<a href="http://books.spec.whatwg.org/">CSS Books</a> does not have the 'footnote-display' property.</li>
+<a href="http://books.ideas.whatwg.org/">CSS Books</a> does not have the 'footnote-display' property.</li>
 <li>
-<a href="http://books.spec.whatwg.org/">CSS Books</a> does not have the 'footnote-policy' property.</li>
+<a href="http://books.ideas.whatwg.org/">CSS Books</a> does not have the 'footnote-policy' property.</li>
 
 
 <li>