rem

by id0

HTML

<section class="wrap">
    <div class="em">em points</div>
    <div class="px">px points</div>
    <div class="rem">rem points</div>
</section>

SCSS

html {
    font-size: 16px;
}

.wrap {
    font-size: 0.75rem;
    display: flex;
    align-items: baseline;
}

div {
    background: grey;
    margin: 20px;
    box-sizing: border-box;
}

.em {
    font-size: 1em;
    width: 10em;
    height: 10em;
    padding: 2em;
}

.rem {
    font-size: 1rem;
    width: 10rem;
    height: 10rem;
    padding: 2rem;
}

.px {
    width: 100px;
    height: 100px;
    padding: 20px;
}