Style a checkbox in firefox — remove check and border

There’s a quite easy way you can do this via <label> tags. Just place a label around the checkbox, and insert a dummy element that will be used for the custom styled checkbox. For example:

label.checkbox input[type="checkbox"] {display:none;}
label.checkbox span {
  display:inline-block;
  border:2px solid #BBB;
  border-radius:10px;
  width:25px;
  height:25px;
  background:#C33;
  vertical-align:middle;
  margin:3px;
  position: relative;
  transition:width 0.1s, height 0.1s, margin 0.1s;
}
label.checkbox :checked + span {
  background:#6F6;
  width:27px;
  height:27px;
  margin: 2px;
}
label.checkbox :checked + span:after {
  content: '\2714';
  font-size: 20px;
  position: absolute;
  top: -2px;
  left: 5px;
  color: #99a1a7;
}

<label class="checkbox">
  <input type="checkbox"/>
  <span></span>
  I like cake
</label>

EDIT: Note that some choices of colours might render the state of your checkbox invisible for colourblind people. When making this code I didn’t think of that, but the above demo might be invisible for R/G colourblind people. When implementing this, please do keep that in mind (pick bright/dark colours for example, or show some difference in shape)

The styles I used are just arbitrary, and you can change that to anything you want. You can even toggle certain text inside it via the ::before pseudo-element, such as what I’ve done here.

I wasn’t able to open the image url you provided to use in your question, but I think you’ll be able to include whatever image you want by simply modifying this code a little. Just change the current background color to the image URL you want to use.

Note: This won’t work in some older browsers.