Fix custom_css import on Space startup

src/display/css_html_js.py

@@ -1,3 +1,4 @@
+# Gradio custom styles for the TSFM Realworld Bench leaderboard.
 custom_css = """
 .markdown-text { font-size: 16px !important; }
 .tab-buttons button { font-size: 20px; }