Rainbow

Faking multiple borders using box-shadow. ...and I turned it into a rainbow.

by mlms13

HTML

<div></div>

CSS

div {
    box-shadow:
        0 0 0 12px white,
        0 0 0 16px purple,
        0 0 0 20px indigo,
        0 0 0 24px blue,
        0 0 0 28px green,
        0 0 0 32px yellow,
        0 0 0 36px orange,
        0 0 0 40px red;
    border-radius: 28px;
    margin: 80px;
    position: relative;
    width: 4px;
    height: 4px;
}
div::after {
    background: #fff;
    content: "";
    height: 44px;
    left: -40px;
    position: absolute;
    width: 84px;
}