switch.css

input[type="checkbox"][role="switch"] {
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    position: relative;
    font-size: inherit;
    width: 2.1em;
    height: 1em;
    box-sizing: content-box;
    border: 1px solid;
    /* border-radius: 1em; */
    vertical-align: text-bottom;
    margin: auto;
    color: var(--theme, inherit);
}

input[type="checkbox"][role="switch"]::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 0;
    transform: translate(0, -50%);
    box-sizing: border-box;
    width: 0.86em;
    height: 0.85em;
    margin: 0 0.15em;
    border: 1px solid;
    /* border-radius: 50%; */
    background: var(--dark, #000);
}

input[type="checkbox"][role="switch"]:checked::before {
    left: 1em;
    background: var(--theme, #000);
    border: 1px solid var(--theme, #000);
}