Add opacity to highway=proposed for less prominent rendering

roads.mss

@@ -699,6 +699,44 @@
 
 .roads-fill,.bridges-fill,.tunnels-fill {
   ::fill {
+    [feature = 'highway_proposed'] {
+      [zoom >= 12] {
+        line-width: 2;
+        line-color: white;
+        line-opacity: 0.2;
+        a/line-width: 2;
+        a/line-color: #9cc;
+        a/line-opacity: 0.2;
+        a/line-dasharray: 2,4;
+        b/line-offset: 2 / 2;
+        b/line-width: 0.1;
+        b/line-color: #9cc;
+        b/line-opacity: 0.2;
+        c/line-offset: -2 / 2;
+        c/line-width: 0.1;
+        c/line-color: #9cc;
+        c/line-opacity: 0.2;
+        [zoom >= 13] {
+          line-width: 3.5;
+          a/line-width: 3.5;
+          a/line-dasharray: 4,6;
+          b/line-offset: 3.5 / 2;
+          b/line-width: 0.25;
+          c/line-offset: -3.5 / 2;
+          c/line-width: 0.25;
+        }
+        [zoom >= 16] {
+          line-width: 7;
+          a/line-width: 7;
+          a/line-dasharray: 6,8;
+          b/line-offset: 7 / 2;
+          b/line-width: 0.5;
+          c/line-offset: -7 / 2;
+          c/line-width: 0.5;
+        }
+      }
+    }
+
     /*
      * The construction rules for small roads are strange, since if construction is null its assumed that
      * it's a more major road. The line-width = 0 could be removed by playing with the query to set a construction
@@ -710,7 +748,6 @@
      * https://github.com/mapbox/carto/issues/235
      * https://github.com/mapbox/carto/issues/237
      */
-    [feature = 'highway_proposed'],
     [feature = 'highway_construction'] {
       [zoom >= 12] {
         line-width: 2;