Let impressions panel match chat width on mobile

The panel is pinned to 360px via flex: 0 0 360px / min-width /
max-width, which on mobile leaves it wider than the chat column it
stacks beneath. Override all three inside the existing max-width: 768px
media query so the panel (and the bar cells / trajectory plot that
flow inside it) follow the chat-column width.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app.py

@@ -323,6 +323,14 @@ ul.options li.selected {
     #prisma-footer .footer-right a {
         margin: 0 0.4rem;
     }
+
+    /* Let the impressions panel match the chat-column width below it. */
+    #impressions-panel {
+        flex: 1 1 auto !important;
+        min-width: 0 !important;
+        max-width: 100% !important;
+        width: 100% !important;
+    }
 }
 """