<p dir="auto">I noticed in 3.1 that <code class="notranslate">.collapse.in</code> breaks <code class="notranslate">width</code> for tbody</p>
<p dir="auto">I believe <code class="notranslate">tbody.collapse.in</code> should be defined to <code class="notranslate">display:table-row-group</code> versus <code class="notranslate">display:block</code>.</p>
<p dir="auto">Since 3.1, I guess, bootstrap has a rule<br>
.collapse.in {<br>
display: block;<br>
}</p>
<p dir="auto">This rule conflicts with <code class="notranslate">&lt;tr&gt;</code> elements which require "display: table-row". And maybe others as well.</p>
<p dir="auto">I haven't searched the sources where this rule is defined. Just using the download bootstrap-3.1.0-dist.zip and there it is defined in bootstrap.css line 2357.</p>