diff --git a/css/map.css b/css/map.css
index 76651bf25..e93ac609c 100644
--- a/css/map.css
+++ b/css/map.css
@@ -97,13 +97,13 @@ path.stroke {
     stroke-width: 2;
 }
 
-path.stroke.railway-rail {
+path.stroke.tag-railway-rail {
     stroke: white;
     stroke-width: 3;
     stroke-dasharray: 12,12;
 }
 
-path.stroke.railway-subway {
+path.stroke.tag-railway-subway {
     stroke: #444;
     stroke-width: 3;
     stroke-dasharray: 8,8;
@@ -120,27 +120,27 @@ path.area.selected {
     stroke-width:4 !important;
 }
 
-path.area.natural {
+path.area.tag-natural {
     stroke: #ADD6A5;
     fill: #ADD6A5;
     stroke-width:1;
 }
 
-path.area.natural.natural-water {
+path.area.tag-natural-water {
     stroke: #6382FF;
     fill: #ADBEFF;
 }
 
-path.area.building {
+path.area.tag-building {
     stroke: #9E176A;
     stroke-width: 1;
     fill: #ff6ec7;
 }
 
-path.area.landuse,
-path.area.natural.natural-wood,
-path.area.natural.natural-tree,
-path.area.natural.natural-grassland {
+path.area.tag-landuse,
+path.area.tag-natural-wood,
+path.area.tag-natural-tree,
+path.area.tag-natural-grassland {
     stroke: #006B34;
     stroke-width: 1;
     fill: #189E59;
@@ -148,97 +148,105 @@ path.area.natural.natural-grassland {
 }
 
 /* highways */
-path.stroke.highway-residential {
+path.stroke.tag-highway-residential {
     stroke:#E8E8E8;
     stroke-width:4;
 }
-path.casing.highway-residential {
+path.casing.tag-highway-residential {
     stroke:#E8E8E8;
     stroke-width:10;
     stroke-opacity:0.4;
 }
 
-path.stroke.highway-unclassified,
-path.stroke.highway-tertiary,
-path.stroke.highway-tertiary_link {
+path.stroke.tag-highway-unclassified,
+path.stroke.tag-highway-tertiary,
+path.stroke.tag-highway-tertiary_link {
     stroke:#FEFECB;
     stroke-width:6;
 }
 
-path.casing.highway-unclassified,
-path.casing.highway-tertiary,
-path.casing.highway-tertiary_link {
+path.casing.tag-highway-unclassified,
+path.casing.tag-highway-tertiary,
+path.casing.tag-highway-tertiary_link {
     stroke-width:8;
 }
 
-path.stroke.highway-service {
+path.stroke.tag-highway-service {
     stroke:#fff;
     stroke-width:4;
 }
-path.casing.highway-service {
+path.casing.tag-highway-service {
     stroke-width:6;
 }
 
-path.stroke.highway-footway,
-path.stroke.highway-cycleway,
-path.stroke.highway-steps {
+path.stroke.tag-highway-footway,
+path.stroke.tag-highway-cycleway,
+path.stroke.tag-highway-steps {
     stroke: #ff6257;
     stroke-width: 3;
     stroke-dasharray: 6, 6;
 }
-path.casing.highway-footway,
-path.casing.highway-cycleway,
-path.casing.highway-steps {
+path.casing.tag-highway-footway,
+path.casing.tag-highway-cycleway,
+path.casing.tag-highway-steps {
     stroke-width: 3;
     stroke: #fff;
 }
 
-path.stroke.highway-motorway, path.stroke.highway-motorway_link {
+path.stroke.tag-highway-motorway,
+path.stroke.tag-highway-motorway_link {
     stroke:#809BC0;
     stroke-width:3;
 }
-path.casing.highway-motorway, path.casing.highway-motorway_link {
+path.casing.tag-highway-motorway,
+path.casing.tag-highway-motorway_link {
     stroke:#809BC0;
     stroke-width:9;
     stroke-opacity:0.4;
 }
 
-path.stroke.highway-trunk, path.stroke.highway-trunk_link {
+path.stroke.tag-highway-trunk,
+path.stroke.tag-highway-trunk_link {
     stroke-width:7;
     stroke-opacity:0.4;
     stroke:#7FC97F;
 }
-path.casing.highway-trunk, path.casing.highway-trunk_link {
+path.casing.tag-highway-trunk,
+path.casing.tag-highway-trunk_link {
     stroke-width:4;
     stroke:#7FC97F;
 }
 
-path.stroke.highway-primary, path.stroke.highway-primary_link {
+path.stroke.tag-highway-primary,
+path.stroke.tag-highway-primary_link {
     stroke:#FD969A;
     stroke-width:5;
 }
-path.casing.highway-primary, path.casing.highway-primary_link {
+path.casing.tag-highway-primary,
+path.casing.tag-highway-primary_link {
     stroke:#FF6363;
     stroke-opacity:0.4;
     stroke-width:12;
 }
 
-path.stroke.highway-secondary, path.stroke.highway-secondary_link {
+path.stroke.tag-highway-secondary,
+path.stroke.tag-highway-secondary_link {
     stroke:#FDBF6F;
     stroke-width:4;
 }
-path.casing.highway-secondary, path.casing.highway-secondary_link {
+path.casing.tag-highway-secondary,
+path.casing.tag-highway-secondary_link {
     stroke-opacity:0.4;
     stroke:#FDBF6F;
     stroke-width:11;
 }
 
-path.stroke.bridge-yes {
+path.stroke.tag-bridge-yes {
     stroke:#eee;
     stroke-width:7;
 }
 
-path.stroke.waterway {
+path.stroke.tag-waterway {
     stroke: #10539a;
     stroke-width: 3;
 }
@@ -247,7 +255,7 @@ text {
     font-size:10px;
 }
 
-text.oneway {
+text.tag-oneway {
     fill:#91CFFF;
     stroke:#2C6B9B;
     stroke-width:1;
diff --git a/js/id/renderer/style.js b/js/id/renderer/style.js
index bf33a1bce..4c35c5650 100644
--- a/js/id/renderer/style.js
+++ b/js/id/renderer/style.js
@@ -56,11 +56,11 @@ iD.Style.TAG_CLASSES = iD.util.trueObj([
 iD.Style.styleClasses = function(pre) {
     return function(d) {
         var tags = d.tags;
-        var c = [pre];
+        var c = pre ? [pre] : [];
         for (var k in tags) {
             if (!iD.Style.TAG_CLASSES[k]) continue;
-            c.push(k + '-' + tags[k]);
-            c.push(k);
+            c.push('tag-' + k);
+            c.push('tag-' + k + '-' + tags[k]);
         }
         return c.join(' ');
     };
diff --git a/test/spec/renderer/style.js b/test/spec/renderer/style.js
index ef0519c3f..b48554c84 100644
--- a/test/spec/renderer/style.js
+++ b/test/spec/renderer/style.js
@@ -1,4 +1,4 @@
-describe('Style', function() {
+describe('iD.Style', function() {
     describe('#waystack', function() {
         it('stacks bridges over non-bridges', function() {
             var a = { tags: { bridge: 'yes' } },
@@ -6,6 +6,7 @@ describe('Style', function() {
             expect(iD.Style.waystack(a, b)).to.equal(1);
             expect(iD.Style.waystack(b, a)).to.equal(-1);
         });
+
         it('stacks layers', function() {
             var a = { tags: { layer: 1 } },
             b = { tags: { layer: 0 } };
@@ -13,14 +14,24 @@ describe('Style', function() {
             expect(iD.Style.waystack(b, a)).to.equal(-1);
         });
     });
+
     describe('#styleClasses', function() {
-        it('no valid classes', function() {
-            var a = { tags: { } };
-            expect(iD.Style.styleClasses('')(a)).to.equal('');
+        it('returns an empty string when no classes are present', function() {
+            var classes = iD.Style.styleClasses(''),
+                entity = iD.Entity();
+            expect(classes(entity)).to.equal('');
         });
-        it('a valid class', function() {
-            var a = { tags: { highway: 'primary' } };
-            expect(iD.Style.styleClasses('')(a)).to.equal(' highway-primary highway');
+
+        it('returns a string containing predefined classes', function() {
+            var classes = iD.Style.styleClasses('selected'),
+                entity = iD.Entity();
+            expect(classes(entity)).to.equal('selected');
+        });
+
+        it('returns a string containing classes for highway tags', function() {
+            var classes = iD.Style.styleClasses(''),
+                entity = iD.Entity({tags: {highway: 'primary'}});
+            expect(classes(entity)).to.equal('tag-highway tag-highway-primary');
         });
     });
 });