Fix color of dialog header and expansion panel (#28087)

Author: timmo001

src/components/ha-dialog-header.ts

@@ -75,11 +75,15 @@ export class HaDialogHeader extends LitElement {
           font-size: var(--ha-font-size-xl);
           line-height: var(--ha-line-height-condensed);
           font-weight: var(--ha-font-weight-medium);
+          color: var(--ha-dialog-header-title-color, var(--primary-text-color));
         }
         .header-subtitle {
           font-size: var(--ha-font-size-m);
           line-height: var(--ha-line-height-normal);
-          color: var(--secondary-text-color);
+          color: var(
+            --ha-dialog-header-subtitle-color,
+            var(--secondary-text-color)
+          );
         }
         @media all and (min-width: 450px) and (min-height: 500px) {
           .header-bar {

src/components/ha-expansion-panel.ts

@@ -209,6 +209,7 @@ export class HaExpansionPanel extends LitElement {
     ::slotted([slot="header"]) {
       flex: 1;
       overflow-wrap: anywhere;
+      color: var(--primary-text-color);
     }
 
     .container {