MDL-14477 - Improve display of tab bars

1. Make disable tabs look more disabled, in particular, make sure they don't do anything when you mouse over them, and make the text colour grey.

2. Put the active tab into bold, to make it look more active.

theme/standard/styles_color.css

@@ -830,6 +830,25 @@ table.message_search_results td {
  *** Tabs
  ***/
 
+.tabtree a.nolink,
+.tabtree .here ul a.nolink {
+  color: #888;
+}
+
+.tabtree a.nolink:hover,
+.tabtree .here ul a.nolink:hover {
+  color: #888;
+}
+
+.tabtree .here a.nolink,
+.tabtree .here ul .here a.nolink {
+  color: black;
+}
+
+.tabtree .here a.nolink:hover,
+.tabtree .here ul .here a.nolink {
+  color: black;
+}
 
 
 /***

theme/standard/styles_fonts.css

@@ -719,6 +719,14 @@ body#grade-index .grades .header {
   text-decoration: none;
 }
 
+.tabtree .here {
+  font-weight: bold;
+}
+
+.tabtree .here ul {
+  font-weight: normal;
+}
+
 /***
  *** Tags
  ***/

theme/standard/styles_layout.css

@@ -2734,19 +2734,23 @@ body.notes .notesgroup {
   padding: 10px 0 0.35em 13px;
 }
 
-.tabrow0 a:hover {
+.tabrow0 a:link:hover,
+.tabrow0 a:visited:hover {
   background-image: url(pix/tab/left_hover.gif);
 }
 
-.tabrow0 .here a:hover {
+.tabrow0 .here a:link:hover,
+.tabrow0 .here a:visited:hover, {
   background-image: url(pix/tab/left.gif);
 }
 
-.tabrow0 a:hover span {
+.tabrow0 a:link:hover span,
+.tabrow0 a:visited:hover span {
   background-image: url(pix/tab/right_hover.gif);
 }
 
-.tabrow0 .here a:hover span {
+.tabrow0 .here a:link:hover span,
+.tabrow0 .here a:visited:hover span {
   background-image: url(pix/tab/right.gif);
 }