Sometimes, when developing, you need to use pixel equivalents, but they are not in memory) add px preview for rems) like <img width="884" alt="Снимок экрана 2020-10-07 в 13 19 34" src="https://user-images.githubusercontent.com/12596485/95319326-68255a00-08a0-11eb-99a2-34fd2d01f55c.png"> and add option for set base size like 16px