When I visit the site on a mobile device, I’m seeing the image taking up the whole background. It doesn’t have any white background like the image you showed.
You may have resolved this issue on your own, but typically when something like this happens it is due to your theme adding, in this case, a white background (or another color in other themes) on top of the background image. This is the equivalent of placing a piece of paper on top of a photograph. The trick is to remove the piece of paper in order to see the photograph.
On a website this is done through CSS by changing the page’s background-color: #ffffff;
to background: none;
. Usually you can right click on your page and find the “Inspect Element” option in your browser. Then you can click around until you find the element(s) with a background color. You can then add CSS to your site in Appearance > Customize > Additional CSS section to remove the background color.
Something like this could work (change .styled-background to the CSS class or ID as appropriate for your theme):
.styled-background {
background: none;
}
It looks like you’ve resolved this on your own though, so hopefully this reply can help others who are needing assistance with the same issue. If you need any further assistance, please let me know.