<input type="checkbox" id="checkbox01" name="demo" /><label for="checkbox01">foo</label>
<input type="checkbox" id="checkbox02" name="demo" /><label for="checkbox02">bar</label>
<input type="checkbox" id="checkbox03" name="demo" /><label for="checkbox03">baz</label>

input[type="checkbox"] {
    display: none;
}
label {
    position: relative;
    display: inline-block;
    padding: 3px 3px 3px 22px;
    cursor: pointer;
    -webkit-transition: all .2s;
    transition: all .2s;
}
label::before,
label::after {
    position: absolute;
    content: '';
    -webkit-transition: all .2s;
    transition: all .2s;
}
label::before {
    top: 50%;
    left: 0;
    width: 14px;
    height: 14px;
    margin-top: -8px;
    background: #f4f4f4;
    border: 1px solid #ccc;
    border-radius: 3px;
}
label::after {
    opacity: 0;
    top: 50%;
    left: 3px;
    width: 8px;
    height: 4px;
    margin-top: -4px;
    border-left: 2px solid #3498db;
    border-bottom: 2px solid #3498db;
    -webkit-transform: rotate(-45deg) scale(.5);
    transform: rotate(-45deg) scale(.5);
}
label:hover::before {
    background: #fff;
}
input[type="checkbox"]:checked + label::before {
    background: #fff;
    border: 1px solid #3498db;
}
input[type="checkbox"]:checked + label::after {
    opacity: 1;
    -webkit-transform: rotate(-45deg) scale(1);
    transform: rotate(-45deg) scale(1);
}