diff --git a/src/themes.ts b/src/themes.ts
index a7a3edd9b3..3338f62b73 100644
--- a/src/themes.ts
+++ b/src/themes.ts
@@ -1,3 +1,5 @@
+import { HorizontalAlignment, VerticalAlignment } from "./base-interfaces";
+
 export type ImageFit = "auto" | "contain" | "cover";
 export type ImageAttachment = "fixed" | "scroll";
 
@@ -58,9 +60,26 @@ export interface ITheme {
   /**
    * An object with survey header settings.
    */
-  header?: {[index: string]: any};
+  header?: IAdvancedHeader;
   /**
    * An object with CSS variables.
    */
   cssVariables?: { [index: string]: string };
 }
+
+export interface IAdvancedHeader {
+  height: number;
+  inheritWidthFrom: "survey" | "page";
+  textAreaWidth: number;
+  // textGlowEnabled: boolean;
+  overlapEnabled: boolean;
+  backgroundImage: string;
+  backgroundImageOpacity: number;
+  backgroundImageFit: "cover" | "fill" | "contain" | "tile";
+  logoPositionX: HorizontalAlignment;
+  logoPositionY: VerticalAlignment;
+  titlePositionX: HorizontalAlignment;
+  titlePositionY: VerticalAlignment;
+  descriptionPositionX: HorizontalAlignment;
+  descriptionPositionY: VerticalAlignment;
+}
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