You can arbitrarily set the height of the website banner section – for example to make a taller banner to show more of the background image, as is shown on this website.
Simply add the following code to the Additional CSS section of the theme customizer:
/* Make the site header taller */
header#site-header {
min-height: 20em;
}This is helpful in cases where you don’t want to put content in the website banner, but you want to see more of the banner image.