To change the background color in the Divi Theme, you can do so by adding CSS to Divi, like so:

@media only screen and ( min-width:981px ) {
    #main-header { min-height: 150px !important; } /* normal */ { min-height: 250px !important;  } /* shrunken header */

A couple of notes:

  • This sets the minimum height rather than the absolute height to allow the header to grow if you add more content too it.
  • The first min-height sets the initial height of the header, while the second sets the height of the header when it is in the “shrunken” state it enters when the user scrolls down.
  • The code above applies the header height settings only on wide displays, so that on mobiles the usual Divi header height will be used.