olalindberg, your question may have been resolved to a certain degree. CrouchingBruin mentioned that after your header appears on your mobile device, you will have a white space between the header and the menu bar. To resolve this, all you have to do after going to your style.css section and finding this code near the bottom half:
/* Collapse oversized image and pulled images after iPad breakpoint. */
@media (max-width: 767px) {
.site-header .home-link {
min-height: 0;
Enter any number in the (min-height: 0;) line, this will simply show a header, but with white space in between it and the menu bar, to fix this issue, all you have to do is simply add the two letters (px) after your number. For example, ( min-height: 110px; ). And there you go, no white space! So you don’t need to ‘set the background-size property of the site-header’ to eliminate that white space.
By the way you could start with a high number like 200 and go down in increments until you see a thin white space, and then you’ll know the next number would take all that white line away, I tried it that way, I went from 200 to 150 to 120, 115, 111 then 110. Simply add the px letters behind your number.