.js-navCollapsed .t-TreeNav .a-TreeView-node--topLevel>.a-TreeView-content.is-hover .a-TreeView-label {
	visibility: visible;
	left: 48px;
	padding: 0 16px;
	width: auto; 
        color: #000000;
	background-color: #CCCCCC; /* This would be your primary color */
}

.apex-side-nav.js-navCollapsed .t-Body-nav
, .apex-side-nav.js-navCollapsed .t-Body-nav .t-TreeNav {
    z-index: 999; /* Make it appear on top of the page content */
}