Fix #2986: themes/basic/defindex.html should be changed for html5 friendly

CHANGES

@@ -24,6 +24,7 @@ Bugs fixed
 * #3009: Bad rendering of parsed-literals in LaTeX since Sphinx 1.4.4
 * #3000: ``option`` directive generates invalid HTML anchors
 * #2984: Invalid HTML has been generated if `html_split_index` enabled
+* #2986: themes/basic/defindex.html should be changed for html5 friendly
 
 Documentation
 -------------

sphinx/themes/basic/defindex.html

@@ -18,13 +18,13 @@
   </p>
   {% block tables %}
   <p><strong>{{ _('Indices and tables:') }}</strong></p>
-  <table class="contentstable" align="center"><tr>
-    <td width="50%">
+  <table class="contentstable"><tr>
+    <td style="width: 50%">
       <p class="biglink"><a class="biglink" href="{{ pathto("contents") }}">{{ _('Complete Table of Contents') }}</a><br>
          <span class="linkdescr">{{ _('lists all sections and subsections') }}</span></p>
       <p class="biglink"><a class="biglink" href="{{ pathto("search") }}">{{ _('Search Page') }}</a><br>
          <span class="linkdescr">{{ _('search this documentation') }}</span></p>
-    </td><td width="50%">
+    </td><td style="width: 50%">
       <p class="biglink"><a class="biglink" href="{{ pathto("modindex") }}">{{ _('Global Module Index') }}</a><br>
          <span class="linkdescr">{{ _('quick access to all modules') }}</span></p>
       <p class="biglink"><a class="biglink" href="{{ pathto("genindex") }}">{{ _('General Index') }}</a><br>

sphinx/themes/basic/static/basic.css_t

@@ -122,6 +122,8 @@ ul.keywordmatches li.goodmatch a {
 
 table.contentstable {
     width: 90%;
+    margin-left: auto;
+    margin-right: auto;
 }
 
 table.contentstable p.biglink {