* 
{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body
{
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #18191f;
}
ul 
{
    position: relative;
    display: flex;
}
ul li 
{
    list-style: none;
}
ul li label
{
    position: relative;
}
ul li label input[type="checkbox"]
{
    position: absolute;
    opacity: 0;
    cursor: pointer;
}
ul li label .icon 
{
    position: relative;
    width: 60px;
    height: 60px;
    background: #18191f;
    color: #555;
    font-size: 24px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    margin: 0 10px;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: -1px -1px 4px rgba(255,255,255,0.05)
                4px 4px 6px rgba(0,0,0,0.02)
                inset -1px -1px 4px rgba(255,255,255,0.05)
                inset 1px 1px 1px rgba(0,0,0,0.01);
}
ul li label .icon:before
{
    content: "";
    position: absolute;
    top: 2px;
    left: 2px;
    width: calc(100% - 5 px);
    height: calc(50% - 2px);
    border-top-left-radius: 8px;
    border-top-right-radius: 8px;
    background: rgba(255,255,255,0.05);
}
ul li label input[type="checkbox"]:checked ~ .icon
{
    box-shadow: inset 0px 0px 2px rgba(255,255,255,0.05)
                inset 4px 4px 6px rgba(0,0,0,0.02);
}
ul li label input[type="checkbox"]:checked ~ .icon .fa
{
    color: #00f3ff;
    text-shadow: 0 0 15 px #00f3ff,
                 0 0 25 px #00f3ff;
    animation: animate 5s linear infinite;
}
@keyframes animate
{
    0%
    {
        filter: hue-rotate(0deg);
    }
    100%
    {
        filter: hue-rotate(360deg);
    }
}