.checkbox{ 
    display: none;
}  

.toggle {
    position: relative;
    display: block;
    width: 10em;
    height: 5em;
}  

.slider {
    position: absolute;
    cursor: pointer;
    width: 100%;
    height: 100%;
    border-radius: 4em;
    background-color: var(--background-dark);
    border: solid 0.25em var(--background);
    -webkit-transition: all 1s ease-in-out;
    transition: all 1s ease-in-out;

    box-shadow: 
        -2px -2px 4px var(--shadow-light), 
        2px 2px 4px var(--shadow-dark),
        inset -1px -1px 2px var(--shadow-light), 
        inset 1px 1px 2px var(--shadow-dark);
}

.slider:before {
    position: absolute;
    content: "";
    height: 3.5em;
    border-radius: 50%;
    width: 3.5em;
    left: .5em;
    top: .5em;
    background-color: var(--background);
    -webkit-transition: all 1s ease-in-out;
    transition: all 1s ease-in-out;
    box-shadow: 
        -2px -2px 4px var(--shadow-light), 
        2px 2px 4px var(--shadow-dark);
}

.checkbox:checked + .slider:before {
    -webkit-transform: translateX(5em);
    -ms-transform: translateX(5em);
    transform: translateX(5em);
}