As you might imagine, the font-size property sets the font-size of text.
Value
Description
(numeric)
e.g. '12' would set the font size to 12 pixels (Microthemer automatically adds the 'px' unit if a unit isn't specified). Other commonly used units include 'em', 'rem', and '%'. So you could enter '1.2em' in the Font Size field.
Font Size
As you might imagine, the font-size property sets the font-size of text.
Themeover CSS Reference
Online CSS References: Font Size
Online CSS Tutorials: Font Size