Merge branch 'OpenOLAT_15.2.uibk' into OpenOLAT_15.3.uibk

src/main/webapp/static/themes/uibk/_uibk_header.scss

@@ -126,7 +126,7 @@ div#o_header_wrapper {
 	min-height: 90px;
 	background: url($uibk-logo-background) no-repeat local left -439px top -329px border-box #fff;
 	position: relative;
-	z-index: 5;
+	z-index: 7;
 }