evansi

Once you get used to thinking in rems, you'll find that it's actually quite easy to express familiar powers of two as fractions of 16, the root font size of every browser. But if you need to express any other value in rems—like odd numbers or very large numbers—you'll need to do the math by hand, convert it with CSS calc, or use a preprocessor like Sass. Alternatively, you can make your life easier using a trick with a root font size of 62.5%.