Оформить чекбокс

CSS

input[type=checkbox],
input[type=radio] { position:absolute; left:-9999px }

input[type=checkbox] + label,
input[type=radio] + label {
    background: url(checkbox.png) 0 50% no-repeat;
    cursor: pointer;
    padding-left: 20px;
}

input[type=checkbox]:checked + label,
input[type=radio]:checked + label { background:url(checkbox-active.png) 0 50% no-repeat; }

HTML

<form>
    <input id="ch1" type="checkbox"><label for="ch1">HTML 5</label>
    <input id="ch2" type="checkbox"><label for="ch2">CSS 3</label>
</form>

Пример кода на JSFiddle