California Code, Elections Code - ELEC § 13203

At the top of the first page of the ballot shall be printed in at least 16-point bold type the words “Official Ballot.” Beneath this heading, the name of the election shall be printed in at least 12-point bold type and, in the case of a partisan primary election, the official party designation or the words “Nonpartisan Ballot” shall be printed, as applicable.  After the heading line or lines, there shall be printed, in at least 12-point type, the date of the election and, in at least 8-point type, the name of the county in which the ballot is to be voted.  The county name may alternatively be displayed in the county seal or logo.  In addition, the ballot shall have printed, at the top or bottom of each card, a ballot style identifier or some other means of identifying the number of the congressional, Senate, and Assembly district.