The Header Content section is comprised of four settings:
Header Content Width deals with the width of the main header area. The main header area holds the site title, site description as well as the header image or logo. The default setting is
75rem, which is equivalent to 1200px wide. This value can be changed to whatever you wish*.
Header Content Background Color deals with the background color of the main header area. The default setting is
Site Description Font Size deals with font size of the site description. The default value is
Site Title Font Size deals with the font size of the site title. The default value is
Once you have made any changes to this area click
Save & Publish
*I recommend that you always try to use rem values. There is a great tool that will help you with calculating rem values called Rem Calulator.