Move config definition

style.less

 /* config */
 
+@camera-extend: 20%;
+
 @hull-width: 350px;
 
 @cruising-move-radius: 5px;
@@ -37,7 +39,6 @@ img, div {
 }
 
 .camera {
-  @camera-extend: 20%;
   left: -@camera-extend;
   top: -@camera-extend;
   width: 100 + 2 * @camera-extend;