Fix dark mode detection and container height (#9617)

Author: pngwn

.changeset/great-toes-leave.md

@@ -0,0 +1,10 @@
+---
+"@gradio/chatbot": minor
+"@gradio/core": minor
+"@gradio/lite": minor
+"@gradio/statustracker": minor
+"@self/app": minor
+"gradio": minor
+---
+
+feat:Fix dark mode detection and container height

gradio/themes/base.py

@@ -86,9 +86,9 @@ def repl_func(match):
             + "\n}"
         )
         dark_css_code = (
-            ".dark {\n"
+            "@media (prefers-color-scheme: dark) {\n:root {\n"
             + "\n".join([f"  --{attr}: {val};" for attr, val in dark_css.items()])
-            + "\n}"
+            + "\n}\n}"
         )
 
         font_css = "\n".join(self._font_css)