While 1200px is the maximum width for any header image, you can make it shorter if you prefer.

A header image is displayed as a percentage of the participant’s screen height based on your file’s original pixel height. The taller your image (up to 450px), the larger it will be on the page.

For example, at 180px or less in height, a header image will take up 10% of the screen. At 450px or more in height, a header image will take up 25% of the screen.

The displayed size is prorated for values between 180–450px. Because header images are responsive to screen size, the displayed pixel size can vary, but aims to be approximately 1/2 of the original asset size, or 2x resolution for sharper image display.