Do not set campground_map’s height via JavaScript

It already has a height set via CSS; no need to overwrite it.

web/static/map.js

@@ -2,7 +2,9 @@
     'use strict';
 
     const container = document.getElementById('campground_map');
-    container.style.height = '80vh';
+    if (!container) {
+        console.warn('could not find map container');
+    }
 
     const svg = container.childNodes[0];
     svg.remove();