fix: respect dark theme when enabled on shadow host (#10558)

Author: vursen

packages/vaadin-lumo-styles/src/global/color-scheme.css

@@ -10,6 +10,7 @@
   color-scheme: light;
 }
 
+:host([theme~='dark']),
 [theme~='dark'] {
   /* Base (background) */
   --lumo-base-color: hsl(214, 35%, 21%);