Make the placeholder style actually look like a placeholder

Author: ThomasKranitsas

src/components/ChallengeEditor/ChallengeName-Field/ChallengeName-Field.module.scss

@@ -52,16 +52,18 @@
   }
 }
 
-@-moz-document url-prefix() {
-  .challengeName {
-    &::-moz-placeholder { /* Mozilla Firefox 19+ */
-      line-height: 38px;
-    }
-    &::-webkit-input-placeholder { /* Webkit */
-      line-height: 38px;
-    }
-    &:-ms-input-placeholder { /* IE */
-      line-height: 38px;
-    }
+.challengeName {
+  &::-moz-placeholder { /* Mozilla Firefox 19+ */
+    line-height: 38px;
+    color: $tc-gray-80;
+  }
+  &::-webkit-input-placeholder { /* Webkit */
+    line-height: 38px;
+    color: $tc-gray-80;
+  }
+  &:-ms-input-placeholder { /* IE */
+    line-height: 38px;
+    color: $tc-gray-80;
   }
 }
+