IF
the icon uses something other than #navBreadCrumb on the Down for Maintenance Page, I can't say without a good look.

If the icon uses the #navBreadCrumb .fa-home like that icon seen on the Crystals page, we can come up with.....

line 129 of the stylesheet will change the gray to whatever color you need.

line 131 covers the change of the background and color on hover.

BUT, lines 129, 132, and 380 get involved as well.

Unfortunately, it's quite common for templates from this source to have multiple elements in the CSS addressing the same item.