Fix loading wrapper transparent background

frontend/src/metabase/components/LoadingAndErrorWrapper.jsx

@@ -51,7 +51,7 @@ export default class LoadingAndErrorWrapper extends Component {
     render() {
         const { loading, error, noBackground, noWrapper } = this.props;
         const contentClassName = cx("wrapper py4 text-brand text-centered flex-full flex flex-column layout-centered", {
-            "bg-transparent": !noBackground
+            "bg-white": !noBackground
         });
         if (noWrapper && !error && !loading) {
             return React.Children.only(this.getChildren());

frontend/src/metabase/dashboards/containers/Dashboards.jsx

@@ -147,6 +147,7 @@ export class Dashboards extends Component {
                 style={{ backgroundColor: "#f9fbfc" }}
                 loading={isLoading}
                 className={cx("relative px4 full-height", {"flex flex-full flex-column": noDashboardsCreated})}
+                noBackground
             >
                 { modalOpen ? this.renderCreateDashboardModal() : null }
                 <div className="flex align-center pt4 pb1">