On home page (in orginal) there is bg image under menu with gradient black.
On other pages, you don't have bg image. I guess, you are not the CSS guy, so you can modify my CSS by using that (first delete older/previus CSS code)
body.default-home #sp-header.transparent-header {
background-image: linear-gradient(180deg, #000000 0%, rgba(0, 0, 0, 0) 100%);}
#sp-header.transparent-header {
background: linear-gradient(180deg, #25522C 0%, rgba(0, 0, 0, 0) 100%);}
And if you want to make solid bg color during mouse hover over it, you can add also that line below:
#sp-header.transparent-header:hover {
background: linear-gradient(180deg, rgba(37,82,44,0.85) 100%, rgba(0, 0, 0, 0) 100%);}
BTW
0.85 - is transparency level (you can try from 0.5 to 0.99).