Change Menu Background Color on Detail Page

In the documentation for Supreme Directory V2 the following appears:

For Supreme the shadow can look ‘unsightly’ on some archive pages.
However, if you want a header border and border shadow, you can use this CSS, and adjust
your colors to suit directly in the CSS:

.sd.search .site-header,
.sd.archive .site-header {
border: 1px solid #e0e0e0;
-moz-box-shadow: 0 1px 1px rgb(104, 55, 89,0.6);
-webkit-box-shadow: 0 1px 1px rgb(104, 55, 89,0.6);
box-shadow: 0 1px 1px rgb(104, 55, 89,0.6);
}

So based on that I used the following to change the color of the site header on the Archive Page from black to blue:

/* Change background color for menu bar on archive pages*/
.sd.search .site-header,
.sd.archive .site-header {
background-color: lightblue;
}

I have tried variations of this to fix the color on the Detail Page, because my logo is unreadable with the black background.

What CSS do I need to use to change the color of the menu bar on the Detail Page?