use chroma and hues from casing colour for oneway arrows

roads.mss

@@ -238,8 +238,12 @@
 @paths-bridge-casing-width:       0.5;
 @paths-tunnel-casing-width:       1;
 
-@oneway-arrow-color: #404040;
-@junction-text-color: #960000;
+@motorway-oneway-arrow-color:     #970031; // Lch(27, 70, 10) derived from motorway-casing
+@trunk-oneway-arrow-color:        #850500; // Lch(27, 65, 42) derived from trunk-casing
+@primary-oneway-arrow-color:      #643400; // Lch(27, 60, 74) derived from primary-casing
+@secondary-oneway-arrow-color:    #3c4500; // Lch(27, 55, 106) derived from secondary-casing
+@default-oneway-arrow-color:      #404040;
+@junction-text-color:             #960000;
 @halo-color-for-minor-road: white;
 
 .roads-casing, .bridges-casing, .tunnels-casing {
@@ -2780,49 +2784,59 @@ tertiary is rendered from z10 and is not included in osm_planet_roads. */
 
 .directions::directions {
   [zoom >= 16] {
-    [oneway = 'yes'] {
-      dira/line-width: 1;
-      dira/line-dasharray: 0,12,10,152;
-      dira/line-color: @oneway-arrow-color;
-      dira/line-join: bevel;
-      dira/line-clip: false;
-      dirb/line-width: 2;
-      dirb/line-dasharray: 0,12,9,153;
-      dirb/line-color: @oneway-arrow-color;
-      dirb/line-join: bevel;
-      dirb/line-clip: false;
-      dirc/line-width: 3;
-      dirc/line-dasharray: 0,18,2,154;
-      dirc/line-color: @oneway-arrow-color;
-      dirc/line-join: bevel;
-      dirc/line-clip: false;
-      dird/line-width: 4;
-      dird/line-dasharray: 0,18,1,155;
-      dird/line-color: @oneway-arrow-color;
-      dird/line-join: bevel;
-      dird/line-clip: false;
-    }
-    [oneway = '-1'] {
-      dira/line-width: 1;
-      dira/line-dasharray: 0,12,10,152;
-      dira/line-color: @oneway-arrow-color;
-      dira/line-join: bevel;
-      dira/line-clip: false;
-      dirb/line-width: 2;
-      dirb/line-dasharray: 0,13,9,152;
-      dirb/line-color: @oneway-arrow-color;
-      dirb/line-join: bevel;
-      dirb/line-clip: false;
-      dirc/line-width: 3;
-      dirc/line-dasharray: 0,14,2,158;
-      dirc/line-color: @oneway-arrow-color;
-      dirc/line-join: bevel;
-      dirc/line-clip: false;
-      dird/line-width: 4;
-      dird/line-dasharray: 0,15,1,158;
-      dird/line-color: @oneway-arrow-color;
-      dird/line-join: bevel;
-      dird/line-clip: false;
+    // omitting highway_: platform, construction
+    [feature = 'highway_motorway'],
+    [feature = 'highway_motorway_link'],
+    [feature = 'highway_trunk'],
+    [feature = 'highway_trunk_link'],
+    [feature = 'highway_primary'],
+    [feature = 'highway_primary_link'],
+    [feature = 'highway_secondary'],
+    [feature = 'highway_secondary_link'],
+    [feature = 'highway_tertiary'],
+    [feature = 'highway_tertiary_link'],
+    [feature = 'highway_residential'],
+    [feature = 'highway_unclassified'],
+    [feature = 'highway_living_street'],
+    [feature = 'highway_road'],
+    [feature = 'highway_service'],
+    [feature = 'highway_raceway'],
+    [feature = 'highway_bridleway'],
+    [feature = 'highway_cycleway'],
+    [feature = 'highway_track'],
+    [feature = 'highway_pedestrian'],
+    [feature = 'highway_footway'],
+    [feature = 'highway_path'],
+    [feature = 'highway_steps'] {
+      [oneway = 'yes'],
+      [oneway = '-1'] {
+        marker-placement: line;
+        marker-spacing: 180;
+        marker-max-error: 0.5;
+        marker-fill: @default-oneway-arrow-color;
+
+        marker-file: url('symbols/oneway.svg');
+        [oneway = '-1'] {
+          marker-file: url('symbols/oneway-reverse.svg');
+        }
+
+        [feature = 'highway_motorway'],
+        [feature = 'highway_motorway_link'] {
+          marker-fill: @motorway-oneway-arrow-color;
+        }
+        [feature = 'highway_trunk'],
+        [feature = 'highway_trunk_link'] {
+          marker-fill: @trunk-oneway-arrow-color;
+        }
+        [feature = 'highway_primary'],
+        [feature = 'highway_primary_link'] {
+          marker-fill: @primary-oneway-arrow-color;
+        }
+        [feature = 'highway_secondary'],
+        [feature = 'highway_secondary_link'] {
+          marker-fill: @secondary-oneway-arrow-color;
+        }
+      }
     }
   }
 }