<!DOCTYPE html>
<style>
* {
width: 0px;
height: 0px;
}
.round {
width: round(down, 85px, 10px);
}
.mod {
width: mod(201px, 101px);
}
.rem {
width: rem(241px, -121px);
}
</style><div class="round"><div class="mod"><div class="rem">