SlowlyReference
Units
The units Slowly uses for sizes, and how rem conversion works.
Most size controls in Slowly take a unit, px, rem, em, percentages, viewport units, and the rest. You can set a default so new values start in the unit you prefer.
Slowly leans on rem for type and spacing, since rem scales with the root font size and keeps a layout proportional. A px value can be converted to rem, so you are not doing the maths by hand.