css form checkbox styling with checked and after tags

Question

I am trying to design a form without using JavaScript or JQuery. It includes a series of checkboxes. The idea is to display a certain gif after the checkbox if it is unchecked. Otherwise, display nothing after it. This is the code I have:

input[type=checkbox]::after
{
  content: url(images/unchecked_after.gif);
  position:relative;
  left:15px;
  z-index:100;
}
input[type=checkbox]:checked::after
{
  content:"";
}

It works in Chrome but doesn't seem to be working in Firefox or IE. What is wrong?

Answer 1

The cross-browser solution that worked for me was to include an empty label (with class "checkbox_label") after the checkbox input and then style IT rather than the checkbox.

input[type=checkbox] + label:after
{
  content: url(images/unchecked_after.gif);
  position:relative;
  left:0px;
  top:1px;
  z-index:100;
}

input[type=checkbox]:checked + label:after
{
  content:"";
}

.checkbox_label
{
  height:0px;
  width:0px;
  display:inline-block;
  float:left;
  position:relative;
  left:20px;
  z-index:100;
}