Cal. Bus. & Prof. Code § 13473

Unless otherwise provided, all letters, figures, or numerals on each sign required by this article, however affixed, marked, imprinted, placed, or embossed, shall be at least three-fourths of an inch in height and all lines or marks used in the making or forming of all the letters, figures, or numerals which are a part of the sign shall be at least one-eighth of an inch in width.