Fix map container overlap and gap issues

- Add overflow: hidden to body and container-map
- Prevents map from extending under filter menu
- Eliminates gap between footer and map

Author: claude

css/catchment.css

@@ -16,11 +16,13 @@ html, body {
 body {
     padding-top: 56px;
     padding-bottom: 56px;
+    overflow: hidden;
 }
 
 .container-map {
     height: 100%;
     position: relative;
+    overflow: hidden;
 }
 
 #map {