<!DOCTYPE HTML> <style> div { background: yellow } div { font-size: 24px; width: 450px } </style> <!-- In a 450px container, the minimum font size at 15em per line is 30px. This means we map 0px-45px into 30px-45px, so 12px gets mapped to 34px. However, because we've enabled the maxRatio at a value of 2.0, the mapping function, which would normally return 34px/12px, or about 2.83, now returns a ratio capped at 2.0, thus the actual font size is 24px. --> <div>Hello world</div>