diff --git a/src/common/color/convert-color.ts b/src/common/color/convert-color.ts
index f48e6184a0..29f95b4283 100644
--- a/src/common/color/convert-color.ts
+++ b/src/common/color/convert-color.ts
@@ -1,10 +1,4 @@
-const expand_hex = (hex: string): string => {
-  let result = "";
-  for (const val of hex) {
-    result += val + val;
-  }
-  return result;
-};
+import { expandHex } from "./hex";
 
 const rgb_hex = (component: number): string => {
   const hex = Math.round(Math.min(Math.max(component, 0), 255)).toString(16);
@@ -14,10 +8,7 @@ const rgb_hex = (component: number): string => {
 // Conversion between HEX and RGB
 
 export const hex2rgb = (hex: string): [number, number, number] => {
-  hex = hex.replace("#", "");
-  if (hex.length === 3 || hex.length === 4) {
-    hex = expand_hex(hex);
-  }
+  hex = expandHex(hex);
 
   return [
     parseInt(hex.substring(0, 2), 16),
diff --git a/src/common/color/hex.ts b/src/common/color/hex.ts
new file mode 100644
index 0000000000..a25b6d6442
--- /dev/null
+++ b/src/common/color/hex.ts
@@ -0,0 +1,24 @@
+export const expandHex = (hex: string): string => {
+  hex = hex.replace("#", "");
+  if (hex.length === 6) return hex;
+  let result = "";
+  for (const val of hex) {
+    result += val + val;
+  }
+  return result;
+};
+
+// Blend 2 hex colors: c1 is placed over c2, blend is c1's opacity.
+export const hexBlend = (c1: string, c2: string, blend = 50): string => {
+  let color = "";
+  c1 = expandHex(c1);
+  c2 = expandHex(c2);
+  for (let i = 0; i <= 5; i += 2) {
+    const h1 = parseInt(c1.substr(i, 2), 16);
+    const h2 = parseInt(c2.substr(i, 2), 16);
+    let hex = Math.floor(h2 + (h1 - h2) * (blend / 100)).toString(16);
+    while (hex.length < 2) hex = "0" + hex;
+    color += hex;
+  }
+  return `#${color}`;
+};
diff --git a/src/common/dom/apply_themes_on_element.ts b/src/common/dom/apply_themes_on_element.ts
index 902a1a196a..4e1aeb9ec6 100644
--- a/src/common/dom/apply_themes_on_element.ts
+++ b/src/common/dom/apply_themes_on_element.ts
@@ -7,6 +7,7 @@ import {
   rgb2hex,
   rgb2lab,
 } from "../color/convert-color";
+import { hexBlend } from "../color/hex";
 import { labBrighten, labDarken } from "../color/lab";
 import { rgbContrast } from "../color/rgb";
 
@@ -37,6 +38,13 @@ export const applyThemesOnElement = (
     if (themeOptions.dark) {
       cacheKey = `${cacheKey}__dark`;
       themeRules = darkStyles;
+      if (themeOptions.primaryColor) {
+        themeRules["app-header-background-color"] = hexBlend(
+          themeOptions.primaryColor,
+          "#121212",
+          8
+        );
+      }
     }
     if (themeOptions.primaryColor) {
       cacheKey = `${cacheKey}__primary_${themeOptions.primaryColor}`;
diff --git a/src/resources/styles.ts b/src/resources/styles.ts
index 2313327b54..c263427770 100644
--- a/src/resources/styles.ts
+++ b/src/resources/styles.ts
@@ -8,7 +8,7 @@ export const darkStyles = {
   "secondary-text-color": "#9b9b9b",
   "disabled-text-color": "#6f6f6f",
   "app-header-text-color": "#e1e1e1",
-  "app-header-background-color": "#1c1c1c",
+  "app-header-background-color": "#101e24",
   "switch-unchecked-button-color": "#999999",
   "switch-unchecked-track-color": "#9b9b9b",
   "divider-color": "rgba(225, 225, 225, .12)",