Andrew, simple custom CSS plugin worked, it colors the other pages header, not the home page header. If you change the color and opacity of the home page change the code. Use a “hex color rgb converter” to get the rgb numbers for the code.
I use #828282 and code becomes
.site-header {
background: rgba(130, 130, 130, 0.20);
left: 0;
position: absolute;
top: 0;
}
the 0.20 opacity you have to visually adjust.
Tnx Andrew!