slider.css

/* Stolen from w3schools
 * I normally wouldn't, but this is one of the few things that's actually good */

  /* The switch - the box around the slider */
.switch {
    position: relative;
    display: inline-block;
    width: 32px;
    height: 20px;
    margin-left: 5px;
    margin-top: 11px;
}

/* Hide default HTML checkbox */
.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

/* The slider */
.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    -webkit-transition: .4s;
    transition: .4s;
    z-index: 2;
    border: 2px solid #555;
    box-sizing: content-box;
}

.slider:before {
    position: absolute;
    content: "";
    height: 12px;
    width: 12px;
    left: 2px;
    bottom: 2px;
    background-color: white;
    -webkit-transition: .4s;
    transition: .4s;
}

input:checked + .slider {
    background-color: #555;
}

input:focus + .slider {
    box-shadow: 0 0 1px #2196F3;
}

input:checked + .slider:before {
    -webkit-transform: translateX(12px);
    -ms-transform: translateX(12px);
    transform: translateX(12px);
}
  
  /* Rounded sliders */
.slider.round {
    border-radius: 20px;
}
  
.slider.round:before {
    border-radius: 50%;
}