Same whole site background image with transparent header and footer

Can someone please assist with the code required to have a single background image run from the very top of the page to the bottom? This would also include the header and footer (i.e. the header and footer would be transparent so the background image runs seamlessly from top to bottom)?

Also I'd like the title heading of each page to have a different background image that would sit ON TOP of the overall page background image if that makes sense?

The overall background image I'm referring to is the image you see on the homepage behind the first block of text.

URL: https://www.lewisandjamil.com/

password: K!nr0ss

Any help would be greatly appreciated!!

You can add this code to Website > Website Tools > Custom CSS

/* Site background image */
body.homepage {
.section-background, .page-section, .section-border {
    background: transparent !important;
}}
body.homepage {
   background-image: url(https://cdn.pixabay.com/photo/2021/01/07/22/15/dandelion-5898546__340.jpg);
   background-size: cover;
   background-repeat: no-repeat;
   background-position: center center;
   background-color: transparent !important;
}