You can use :after
pseudo-element instead of redundant div.close
CSS:
.colsgroup:after {
content:'';
display:block;
float: none;
clear: both;
}
HTML:
<div class="colsgroup" id="sample">
<div class="column">col 1</div>
<div class="column">col 2</div>
<div class="column">col 3</div>
<!-- no redundant div.close here -->
</div>
Live demo: http://jsbin.com/uMEjOV/5/edit
CSS pseudo-elements are really useful in cases where you need to reduce amount of additional decorative/helper elements, making HTML markup lighter. You can read more about them here: http://www.w3.org/TR/CSS2/selector.html#before-and-after