Allow anchors to word-break anywhere

Anchors with very long unbreakable links cause pages to be
horizontally scrollable on mobile.

Fix this by allowing anchors to break anywhere.

Author: NadavTasher

sphinx/themes/basic/static/basic.css.jinja

@@ -230,6 +230,10 @@ a:visited {
     color: #551A8B;
 }
 
+a {
+    word-break: break-all;
+}
+
 h1:hover > a.headerlink,
 h2:hover > a.headerlink,
 h3:hover > a.headerlink,