diff --git a/apps/web/src/appInit.tsx b/apps/web/src/appInit.tsx
index ccb7a8b82000e..8b2c9df02e25f 100644
--- a/apps/web/src/appInit.tsx
+++ b/apps/web/src/appInit.tsx
@@ -5,6 +5,7 @@ import * as Schema from "effect/Schema";
 
 import { applyAppearanceContrast } from "./appearanceContrast";
 import { applyAppearanceFontVariables, TYPOGRAPHY_ADVANCED_STORAGE_KEY } from "./appearanceFonts";
+import { applyGlassAppearance } from "./appearanceGlass";
 import { startElectronBrowserHost } from "./browser/ElectronBrowserHost";
 import { startBrowserProfileReporting } from "./browser/BrowserProfileReporter";
 import { startPreviewTitleRecording } from "./browserHistoryStore";
@@ -83,12 +84,7 @@ function startClientAppearance(): void {
       applyAppearanceContrast(root, settings.appearanceContrast);
     }
     if (previous?.glassOpacity !== settings.glassOpacity) {
-      root.style.setProperty("--glass-opacity", `${settings.glassOpacity}%`);
-      if (settings.glassOpacity === 100) {
-        root.style.setProperty("--glass-blur", "0px");
-      } else {
-        root.style.removeProperty("--glass-blur");
-      }
+      applyGlassAppearance(root, settings.glassOpacity);
     }
     if (
       previous?.fontFamilySans !== settings.fontFamilySans ||
diff --git a/apps/web/src/appearanceGlass.ts b/apps/web/src/appearanceGlass.ts
new file mode 100644
index 0000000000000..1d527e5773cbf
--- /dev/null
+++ b/apps/web/src/appearanceGlass.ts
@@ -0,0 +1,10 @@
+export function applyGlassAppearance(root: HTMLElement, opacity: number): void {
+  root.style.setProperty("--glass-opacity", `${opacity}%`);
+  if (opacity === 100) {
+    root.style.setProperty("--glass-blur", "0px");
+    root.style.setProperty("--dialog-backdrop-filter", "none");
+  } else {
+    root.style.removeProperty("--glass-blur");
+    root.style.removeProperty("--dialog-backdrop-filter");
+  }
+}
diff --git a/apps/web/src/components/ui/dialog.browser.test.tsx b/apps/web/src/components/ui/dialog.browser.test.tsx
new file mode 100644
index 0000000000000..b82b66abcae70
--- /dev/null
+++ b/apps/web/src/components/ui/dialog.browser.test.tsx
@@ -0,0 +1,60 @@
+import { expect, it, vi } from "vite-plus/test";
+import { page } from "vite-plus/test/browser";
+
+import "~/index.css";
+import { render } from "../../../test/render";
+import { applyGlassAppearance } from "../../appearanceGlass";
+import { Dialog, DialogPopup } from "./dialog";
+
+function setup(opacity: number) {
+  const root = document.documentElement;
+  const attributes = ["style", "class"].map((name) => ({ name, value: root.getAttribute(name) }));
+  const motion = document.createElement("style");
+  motion.textContent = '[data-slot="dialog-backdrop"] { transition: none !important; }';
+  document.head.append(motion);
+  applyGlassAppearance(root, opacity);
+  return {
+    [Symbol.dispose]() {
+      motion.remove();
+      for (const { name, value } of attributes) {
+        if (value === null) root.removeAttribute(name);
+        else root.setAttribute(name, value);
+      }
+    },
+  };
+}
+
+it.each([80, 100])(
+  "applies glass opacity %i and updates backdrop filtering without changing dimming",
+  async (initialOpacity) => {
+    using _appearance = setup(initialOpacity);
+    await using _screen = await render(
+      <Dialog open>
+        <DialogPopup aria-label="Example dialog">Dialog content</DialogPopup>
+      </Dialog>,
+    );
+    await expect.element(page.getByRole("dialog", { name: "Example dialog" })).toBeVisible();
+    const backdrop = document.querySelector('[data-slot="dialog-backdrop"]');
+    if (!(backdrop instanceof HTMLElement)) throw new Error("Missing dialog backdrop");
+    const root = document.documentElement;
+    expect(getComputedStyle(backdrop).backdropFilter).toBe(
+      initialOpacity === 100 ? "none" : "blur(4px)",
+    );
+
+    for (const appearance of ["light", "dark"]) {
+      root.classList.toggle("dark", appearance === "dark");
+      const tint = getComputedStyle(backdrop).backgroundColor;
+      for (const opacity of [100, 95, 100, 80]) {
+        applyGlassAppearance(root, opacity);
+        const opaque = opacity === 100;
+        await vi.waitFor(() =>
+          expect(getComputedStyle(backdrop).backdropFilter).toBe(opaque ? "none" : "blur(4px)"),
+        );
+        expect(root.style.getPropertyValue("--glass-opacity")).toBe(`${opacity}%`);
+        expect(root.style.getPropertyValue("--glass-blur")).toBe(opaque ? "0px" : "");
+        expect(root.style.getPropertyValue("--dialog-backdrop-filter")).toBe(opaque ? "none" : "");
+        expect(getComputedStyle(backdrop).backgroundColor).toBe(tint);
+      }
+    }
+  },
+);
diff --git a/apps/web/src/index.css b/apps/web/src/index.css
index a8f3d33c1853d..9baf9ae2c6f1c 100644
--- a/apps/web/src/index.css
+++ b/apps/web/src/index.css
@@ -443,8 +443,8 @@ html[data-mobile-composer-route-transition="true"]::view-transition-old(t3-mobil
 
 @utility dialog-backdrop {
   background: color-mix(in srgb, var(--background) 60%, transparent);
-  -webkit-backdrop-filter: blur(4px);
-  backdrop-filter: blur(4px);
+  -webkit-backdrop-filter: var(--dialog-backdrop-filter, blur(4px));
+  backdrop-filter: var(--dialog-backdrop-filter, blur(4px));
 
   @variant dark {
     background: color-mix(in srgb, var(--background) 64%, transparent);