UI/setting split page bg color from main bg color (ILIAS-eLearning#7998)

templates/default/010-settings/_settings_color-palette.scss

@@ -27,6 +27,8 @@ $il-neutral-light-color: #737373 !default;
 
 //** Base Background Color, e.g. applied to Meta Bar and Breadcrumbs in Default, but also to panels in main content area.
 $il-main-bg: white !default;
+//** Page background color
+$il-page-bg: $il-main-bg !default;
 //** Title area of various components such as Panels. Used as e.g. in containers as bg. Used to be $il-secondary-bg
 $il-main-dark-bg: #f9f9f9 !default;
 //** Background of subelements like subforms. Used mainly on the main-dark-bg.

templates/default/070-components/UI-framework/Layout/_ui-component_standardpage.scss

@@ -23,7 +23,7 @@ grid-based layout
 
 // main grid without slates
 .il-layout-page {
-	background: $il-main-bg;
+	background: $il-page-bg;
 	display: grid;
 	grid-gap: 0px;
     grid-template-columns: auto 1fr;
@@ -231,7 +231,7 @@ footer {
 @media only screen and (max-width: $il-grid-float-breakpoint-max) {
 	// main grid without slates
 	.il-layout-page {
-		background: $il-main-bg;
+		background: $il-page-bg;
 		display: block;
 		overflow: initial;
 		width: 100%;