Custom accessible checkbox and radio elements

by jamessouth

HTML

<h1>
Custom Accessible Form Inputs
</h1>

<p>
  These custom elements are rendered using CSS only with no images. Best efforts have been made to make them acessible but I haven't tested with a screenreader (yet).
</p>
<p>
  The inputs are hidden using established techniques to still allow focus and are replaced using pseudo elements to allow styling.
</p>
<p>
  Tested on IE11 (IE9, IE10 Emulation Only), Edge, Chrome, Firefox, and Opera.
</p>

<form>
  <input type="radio" name="radio" id="radio1" />
  <label for="radio1">Radio One</label>
  <input type="radio" name="radio" id="radio2" />
  <label for="radio2">Radio Two</label>

  <hr/>
  <input type="checkbox" name="checkbox" id="checkbox1" />
  <label for="checkbox1">Checkbox One</label>
  <input type="checkbox" name="checkbox" id="checkbox2" />
  <label for="checkbox2">Checkbox Two</label>

  <hr/>
  <input type="radio" name="radio3" id="radio3" disabled />
  <label for="radio3">Disabled Radio </label>
  <input type="checkbox" name="checkbox3" id="checkbox3" disabled />
  <label for="checkbox3">Disabled Checkbox </label>
</form>

CSS

*,
*:before,
*:after {
  box-sizing: border-box;
}

label[for] {
  display: block;
  margin-bottom: 1rem;
  cursor: pointer;
}

input[type=radio],
input[type=checkbox] {
  /* Hidden yet focusable.*/
  border: 0;
  clip: rect(0 0 0 0);
  height: 1px;
  margin: -1px;
  overflow: hidden;
  padding: 0;
  position: absolute;
  width: 1px;
}

input[type=radio] + label,
input[type=checkbox] + label {
  position: relative;
  padding-left: 1.5rem;
}

input[type=radio] + label:before,
input[type=checkbox] + label:before {
  position: absolute;
  top: 0;
  left: 0;
  width: 1rem;
  height: 1rem;
  display: block;
  border: 2px solid black;
  text-align: center;
  line-height: 0.5;
  font-size: 1.2rem;
  content: "";
}

input[type=radio] + label:before {
  border-radius: 100%;
  background-color: white;
}


/* Checked */

input[type=radio]:checked + label:before {
  background-color: black;
  border: 2px solid white;
  box-shadow: 0 0 0 2px black;
  width: calc(1rem - 4px);
  height: calc(1rem - 4px);
  top: 2px;
  left: 2px;
}

input[type=checkbox]:checked + label:before {
  content: "";
  background-image: url(data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCA0NDguOCA0NDguOCI+PHBhdGggZD0iTTE0Mi44IDMyMy44NUwzNS43IDIxNi43NSAwIDI1Mi40NWwxNDIuOCAxNDIuOCAzMDYtMzA2LTM1LjctMzUuNyIvPjwvc3ZnPg==);
  background-size: cover;
}


/* Focus */

input[type=radio]:focus + label:before,
input[type=checkbox]:focus + label:before {
  border-color: #3b99fc;
}


/* Focus */

input[type=radio]:disabled + label,
input[type=checkbox]:disabled + label {
  cursor: text;
}

input[type=radio]:disabled + label:before,
input[type=checkbox]:disabled + label:before {
  border-color: silver;
  color: silver;
}