You don’t have to add units unless you want to use a specific unit or you’re adding Custom CSS properties.
Within the style builder there are lots of input fields for CSS properties that are expecting a number. These are usually to specify a length or size. When presented with one of these, you have the option to include or not include a unit after the value e.g. 100 or 100px.
DX8 automatically interprets unit-less values for lengths e.g. (width 100) as pixels and then converts this to REM's (a length that is relative to your route base font size). When the number represents something other than a length e.g. (degrees 45), DX8 automatically uses the correct unit. For this reason, we recommend that you don't add units after a value unless you want the value to use a specific unit e.g. 100px, 100%, 100vh etc.
The units you can add after the value are specific to the CSS property. DX8 will not let you add units that cannot be used with a specific CSS property. If you do, you will see an instant validation error.