diff --git a/src/gui/__main__.py b/src/gui/__main__.py
index c230e93..0f4b346 100644
--- a/src/gui/__main__.py
+++ b/src/gui/__main__.py
@@ -1,8 +1,70 @@
-"""Allow running as ``python -m src.gui``."""
+"""Allow running as ``python -m src.gui``.
 
+Launches Streamlit with headless=true and opens Chrome in --app mode
+so the window has no address bar, tabs, or bookmarks — looks like a
+native desktop app.
+"""
+
+import os
+import shutil
 import subprocess
 import sys
+import threading
+import time
 from pathlib import Path
 
+_URL = "http://localhost:8501"
+
+
+def _find_chrome() -> str | None:
+    """Return the path to a Chrome/Chromium executable, or None."""
+    # Check PATH first
+    for name in ("chrome", "google-chrome", "google-chrome-stable", "chromium", "chromium-browser"):
+        found = shutil.which(name)
+        if found:
+            return found
+
+    # Windows common install locations
+    if sys.platform == "win32":
+        candidates = [
+            Path(os.environ.get("PROGRAMFILES", r"C:\Program Files"))
+            / "Google" / "Chrome" / "Application" / "chrome.exe",
+            Path(os.environ.get("PROGRAMFILES(X86)", r"C:\Program Files (x86)"))
+            / "Google" / "Chrome" / "Application" / "chrome.exe",
+            Path(os.environ.get("LOCALAPPDATA", ""))
+            / "Google" / "Chrome" / "Application" / "chrome.exe",
+        ]
+        for c in candidates:
+            if c.exists():
+                return str(c)
+
+    # macOS
+    if sys.platform == "darwin":
+        mac_chrome = Path("/Applications/Google Chrome.app/Contents/MacOS/Google Chrome")
+        if mac_chrome.exists():
+            return str(mac_chrome)
+
+    return None
+
+
+def _open_app_window() -> None:
+    """Wait for the server, then open Chrome in app mode (no address bar)."""
+    time.sleep(2)
+    chrome = _find_chrome()
+    if chrome:
+        subprocess.Popen([chrome, f"--app={_URL}"])
+    else:
+        # Fallback: open in default browser (will have address bar)
+        import webbrowser
+        webbrowser.open(_URL)
+
+
 app_path = Path(__file__).parent / "app.py"
-subprocess.run([sys.executable, "-m", "streamlit", "run", str(app_path)])
+
+# Open the browser in a background thread so it doesn't block Streamlit
+threading.Thread(target=_open_app_window, daemon=True).start()
+
+subprocess.run([
+    sys.executable, "-m", "streamlit", "run", str(app_path),
+    "--server.headless", "true",
+])