style(dashboard): improve small-screen layout

static/style.css

@@ -481,3 +481,16 @@ body {
 @media (pointer: coarse) {
     button, .card { -webkit-tap-highlight-color: transparent; }
 }
+
+/* ─── Small Screens ────────────────────────────────────────────────────────── */
+@media (max-width: 420px) {
+    html { font-size: 13px; }
+    .stat { min-width: 48px; }
+    .stat-num { font-size: 1.15rem; }
+    .tabs-bar { top: 48px; }
+    .search-box { flex-wrap: wrap; }
+    #searchInput { flex: 1 1 100%; }
+    #filterSelect, #exportFormat, .btn-export { flex: 1 1 calc(33% - 6px); }
+    .modal { padding: 14px 10px; }
+    .modal-content { padding: 16px 12px; }
+}