index.html

<div class="some-float-clearing-class">
  <label><input type="checkbox" /> Some Label</label>
</div>

site.js

$('label input').change(function(){
  $(this).parent().toggleClass('selected')
})

style.css

label {
  display:block;
  width: 150px;
  float: left;
  font-size: 13px;
  line-height: 16px;
  margin: 0 0 5px 20px;
  padding: 5px;
  cursor:pointer;
  border-radius:3px;
  -moz-border-radius:3px;
}
label:hover, label.selected{
	background:#ccc;
}