I use images to replace the label for the checkbox, but I don't know how to change the images when the mouse is hovered using external js.
<fieldset id="box">
<legend>choices</legend>
<ul id="container">
<li id="ch1">
<input id="check1" type="checkbox" />
<label class="cb" for="check1"> 1 </label>
</li>
<li id="ch2">
<input id="check2" type="checkbox" />
<label class="cb" for="check2">2</label>
</li>
<li id="ch3">
<input id="check3" type="checkbox" />
<label class="cb" for="check3">3 </label>
</li>
</ul>
</fieldset>