In the following style:
.slider div div div h2 span { color:#ae663d;}
What is the purpose of "div div div"?
In the following style:
.slider div div div h2 span { color:#ae663d;}
What is the purpose of "div div div"?
It specifies that the rule applies to span tags, contained in h2 tags, contained in three nested divs, under a tag with class 'slider'.
Something like this, where the <span> containing "here" will be matched:
<body class="slider">
<div>
<div>
<div>
<h2>Header text <span>here</span></h2>
</div>
</div>
</div>
</body>
.slider h2 span would have been specific enough.