set warning colour to orange rather than amber for better contrast

src/styles.scss

@@ -74,7 +74,7 @@ $custom-typography: mat-typography-config(
 .strudel-light-theme {
   $strudel-app-primary: mat-palette($md-monashpalette);
   $strudel-app-accent:  mat-palette($mat-pink, A200, A100, A400);
-  $strudel-app-warn:  mat-palette($mat-amber);
+  $strudel-app-warn:  mat-palette($mat-orange);
   $strudel-app-theme:   mat-light-theme($strudel-app-primary, $strudel-app-accent, $strudel-app-warn);
 //  @include mat-base-typography($custom-typography);
   @include angular-material-typography($custom-typography);