Force light theme + light-surface safety (HF defaults to dark)

app.py

@@ -149,6 +149,9 @@ CSS = """
   --nn-card:#ffffff; --nn-line:rgba(15,23,42,.08); --nn-accent:%s;
   --nn-font:'Plus Jakarta Sans','Inter',system-ui,sans-serif;
 }
+/* Safety: keep a light surface even before the light-theme redirect settles. */
+html, body, gradio-app, .dark { background:#ffffff !important; }
+.gradio-container, .gradio-container * { color: var(--nn-ink); }
 .gradio-container { max-width: 880px !important; background:
   radial-gradient(1200px 500px at 15%% -10%%, var(--nn-bg1), transparent 60%%),
   radial-gradient(1000px 500px at 110%% 10%%, var(--nn-bg2), transparent 55%%) !important; }
@@ -236,7 +239,19 @@ theme = gr.themes.Soft(
           "system-ui", "sans-serif"],
 )
 
-with gr.Blocks(title="Neural Net From Scratch (NumPy)", theme=theme, css=CSS) as demo:
+# Hugging Face Spaces default to dark mode. This bespoke UI is designed light, so
+# force the light theme on load (one redirect if the param is missing, then never again).
+FORCE_LIGHT = """
+function() {
+  const u = new URL(window.location.href);
+  if (u.searchParams.get('__theme') !== 'light') {
+    u.searchParams.set('__theme', 'light');
+    window.location.replace(u.href);
+  }
+}
+"""
+
+with gr.Blocks(title="Neural Net From Scratch (NumPy)", theme=theme, css=CSS, js=FORCE_LIGHT) as demo:
     gr.HTML(
         '<div id="nn-head"><span class="nn-pill">DEEP LEARNING · NO FRAMEWORK</span>'
         "<h1>A neural network I wrote by hand</h1>"