improve styling for mobile of map list (#605)

app/assets/stylesheets/mobile.css.erb

@@ -69,6 +69,33 @@
     width: 100%;
     padding: 0;
   }
+  
+  #exploreMaps > div {
+    margin-top: 70px;
+  }
+}
+
+/* Smartphones (portrait) ----------- */
+@media only screen and (max-width : 320px) {
+
+  .map {
+    width: 100%;
+    margin: 0 0 30px 0;
+    height: auto;
+  }
+  
+  .mapCard {
+    height: auto;
+  }
+  
+  .mapCard .title {
+    text-align: left;
+  }
+  
+  .mapCard .mapScreenshot {
+    display: none;
+  }
+
 }
 
 #mobile_header {