<section class="slide" data-bg="one"></section> <section class="slide" data-bg="two"></section> <section class="slide" data-bg="three"></section>
.slide{ background-image: url(img/attr(data-bg).jpg); }
.slide[data-bg="one"]{ background-image: url('img/one.jpg'); } .slide[data-bg="two"]{ background-image: url('img/two.jpg'); } ...
