 <p>The second one is a completely different selector. <code>tr .c</code> with a space in between looks for an element with class name "c" that has an ancestor <code>&lt;tr&gt;</code> element. The first one <code>tr.c</code> looks for a <code>&lt;tr&gt;</code> element that has the class name "c".</p> <p>This has nothing to do with specificity, but instead your understanding of CSS.</p>