<input type="radio" name="sex" value="f" data-icon='' />
<input type="radio" name="sex" value="m" data-icon='' />
@import url('//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css');

body {
    background: #e67e22;
    position:absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}

input[name='sex'] {
    -webkit-appearance: none;
    -moz-appearance: none;
    -o-appearance: none;
    -ms-appearance: none;
    appearance: none;
    outline: none;
    
    &:after {
        font-family: 'FontAwesome';
        display: inline-block;
        text-align: center;
        font-size: 80px;
        content: attr(data-icon);
        padding: 20px 20px;
        border-radius: 15px;
        color: rgba(0,0,0,.4);
        transition: box-shadow 1s, color 1s;
    }
    
    &:checked {
        &:after {
            box-shadow: 2px 2px 14px rgba(0,0,0,.4);
            color: rgba(255,255,255,.6);
        }
    }
}
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