main.css

body{
    margin: 0;
    padding: 0;
    background: #292929;
}
.check{
    position: absolute;
    top:50%;
    left: 50%;
    transform: translate(-50%,-50%); 
}
input[type="checkbox"]{
    position: relative;
    width: 480px;
    height: 160px;
    -webkit-appearance:none;
    background: linear-gradient(0deg, #333, #000);
    outline: none;
    border-radius: 80px;
    box-shadow: 0 0 0 4px #353535,0 0 0 5px #3e3e3e, inset 0 0 10px black;
}
input:checked[type="checkbox"]{
    background: linear-gradient(0deg, #6dd1ff, #20b7ff);
    box-shadow: 0 0 0 4px #353535,0 0 0 5px #3e3e3e, inset 0 0 10px black;
}
input[type="checkbox"]:before{
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 360px;
    height:160px;
    background: linear-gradient(0deg, #000, #6b6b6b);
    border-radius: 80px;
    box-shadow: 0 0 0 1px #232323;
    transform: scale(.98,.96);
    transition: .5s;
}
input:checked[type="checkbox"]:before{
    left: 120px;
}
input[type="checkbox"]:after{
    content: "";
    position: absolute;
    top: 72px;
    left:300px;
    width: 16px;
    height: 16px;
    background: linear-gradient(0deg, #6b6b6b, #000);
    border-radius: 50%;
    transition: .5s;
}
input:checked[type="checkbox"]:after{
    background:#63cdff;
    left: 432px;
    box-shadow: 0 0 5px #13b3ff,0 0 15px #13b3ff; 
}