simple checkbox css (webkit only)

gistfile1.html

<form>
    <input type="checkbox" checked="checked" />
    <input type="checkbox" />
</form>

gistfile2.css

/* webkit only */

input {
    margin: 0;
    padding: 0;
}
input[type="checkbox"],
input[type="checkbox"]:before,
input[type="checkbox"]:after {
    border-radius: 8px;
    -webkit-box-sizing: border-box;
}
input[type="checkbox"] {
    position: relative;
    display: inline-block;
    overflow: visible;
    width: 40px;
    height: 40px;
    margin: 0;
    padding: 0;
 
    border-radius: 6px;
    border: 1px solid #222;
 
    -webkit-appearance: none;
    -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
 
    background: none;
    z-index: 3;
}
input[type="checkbox"]:before,
input[type="checkbox"]:after {
    display: block;
    width: 38px;
    height: 38px;
    position: absolute;
    top: 0;
    left: 0;
}
input[type="checkbox"]:before {
    content: "";
    background: #666;
    z-index: 2;
    
    border-radius: 6px;
    
    -webkit-box-shadow: inset 1px 1px 2px rgba(0, 0, 0, 0.6);
    box-shadow: inset 1px 1px 2px rgba(0, 0, 0, 0.6);
}
input[type="checkbox"]:after {
    content: "\2714";
    font-size: 30px;
    font-weight: bold;
    line-height: 38px;
    text-align: center;
    color: #888;
    z-index: 3;
    text-shadow: -1px -1px 1px rgba(30, 30, 30, 0.5), 1px 1px 1px rgba(200, 200, 200, 0.5); 
}
input[type="checkbox"]:checked:after {
    color: #00ff00;
}