diff --git a/apps/client/src/services/css_class_manager.spec.ts b/apps/client/src/services/css_class_manager.spec.ts
new file mode 100644
index 000000000..b49e8c0ab
--- /dev/null
+++ b/apps/client/src/services/css_class_manager.spec.ts
@@ -0,0 +1,14 @@
+import { describe, expect, it } from "vitest";
+
+import { getReadableTextColor } from "./css_class_manager";
+
+describe("getReadableTextColor", () => {
+    it("doesn't crash for invalid color", () => {
+        expect(getReadableTextColor("RandomColor")).toBe("#000");
+    });
+
+    it("tolerates different casing", () => {
+        expect(getReadableTextColor("Blue"))
+            .toBe(getReadableTextColor("blue"));
+    });
+});
diff --git a/apps/client/src/services/css_class_manager.ts b/apps/client/src/services/css_class_manager.ts
index 5aa73e32b..de1c98b87 100644
--- a/apps/client/src/services/css_class_manager.ts
+++ b/apps/client/src/services/css_class_manager.ts
@@ -1,21 +1,22 @@
 import clsx from "clsx";
-import {readCssVar} from "../utils/css-var";
 import Color, { ColorInstance } from "color";
 
+import {readCssVar} from "../utils/css-var";
+
 const registeredClasses = new Set<string>();
 const colorsWithHue = new Set<string>();
 
 // Read the color lightness limits defined in the theme as CSS variables
 
 const lightThemeColorMaxLightness = readCssVar(
-                                        document.documentElement,
-                                        "tree-item-light-theme-max-color-lightness"
-                                    ).asNumber(70);
+    document.documentElement,
+    "tree-item-light-theme-max-color-lightness"
+).asNumber(70);
 
 const darkThemeColorMinLightness = readCssVar(
-                                        document.documentElement,
-                                        "tree-item-dark-theme-min-color-lightness"
-                                    ).asNumber(50);
+    document.documentElement,
+    "tree-item-dark-theme-min-color-lightness"
+).asNumber(50);
 
 function createClassForColor(colorString: string | null) {
     if (!colorString?.trim()) return "";
@@ -27,7 +28,7 @@ function createClassForColor(colorString: string | null) {
 
     if (!registeredClasses.has(className)) {
         const adjustedColor = adjustColorLightness(color, lightThemeColorMaxLightness!,
-                                                   darkThemeColorMinLightness!);
+            darkThemeColorMinLightness!);
         const hue = getHue(color);
 
         $("head").append(`<style>
@@ -50,7 +51,7 @@ function createClassForColor(colorString: string | null) {
 
 function parseColor(color: string) {
     try {
-        return Color(color);
+        return Color(color.toLowerCase());
     } catch (ex) {
         console.error(ex);
     }
@@ -84,8 +85,8 @@ function getHue(color: ColorInstance) {
 }
 
 export function getReadableTextColor(bgColor: string) {
-    const colorInstance = Color(bgColor);
-    return colorInstance.isLight() ? "#000" : "#fff";
+    const colorInstance = parseColor(bgColor);
+    return !colorInstance || colorInstance?.isLight() ? "#000" : "#fff";
 }
 
 export default {