css: fix mobile-stack selector (Gradio 5.x has no gradio-container / .gr-column)

The previous mobile media query used [class*="gradio-container"] .gr-column
selectors, but Gradio 5.x renders the row as .row.layout-gap with .column
children and no gradio-container ancestor — so the rule matched nothing and
the columns never stacked. Use plain .layout-gap / .column selectors.

app.py

@@ -1195,17 +1195,21 @@ footer { display: none !important; }
    side; below ~900px they get squished — and because an earlier rule forces
    `min-width: 0` on them, they squeeze instead of wrapping, collapsing text
    to one character per line. Forcing the row to flex-direction:column makes
-   each column take the full width and stack cleanly. */
+   each column take the full width and stack cleanly.
+   NOTE: Gradio 5.x renders the row as `.row.layout-gap` and the columns as
+   `.column` (no `gradio-container` ancestor, no `.gr-column`), so the
+   selectors must be plain. */
 @media (max-width: 900px) {
-  [class*="gradio-container"] .layout-gap {
+  .layout-gap,
+  .row.layout-gap {
     flex-direction: column !important;
     flex-wrap: wrap !important;
   }
-  [class*="gradio-container"] .layout-gap > .gr-column,
-  [class*="gradio-container"] .layout-gap > div {
+  .layout-gap > .column,
+  .layout-gap > div {
     width: 100% !important;
     max-width: 100% !important;
-    flex: 1 1 100% !important;
+    flex: 1 1 auto !important;
   }
 }
 """