further tweaked sepia palette; shored up TestTray for headless browser pipeline testing

src/functional_tests/base.py

@@ -37,13 +37,24 @@ def wait(fn):
 # Functional Tests
 class FunctionalTest(StaticLiveServerTestCase):
     # Helper methods
-    def setUp(self):
+    def _make_browser(self, width=1366, height=900):
+        """Create a Firefox instance sized to width×height.
+        In headless CI, pass --width/--height as binary args so the CSS
+        media query (orientation: landscape/portrait) is correct from the
+        first paint — set_window_size() alone is unreliable in headless mode.
+        """
         options = webdriver.FirefoxOptions()
         headless = os.environ.get("HEADLESS")
         if headless:
             options.add_argument("--headless")
-        self.browser = webdriver.Firefox(options=options)
-        self.browser.set_window_size(1366, 900)
+            options.add_argument(f"--width={width}")
+            options.add_argument(f"--height={height}")
+        browser = webdriver.Firefox(options=options)
+        browser.set_window_size(width, height)
+        return browser
+
+    def setUp(self):
+        self.browser = self._make_browser(1366, 900)
         self.test_server = os.environ.get("TEST_SERVER")
         if self.test_server:
             self.live_server_url = 'http://' + self.test_server