Makes the hint text darker for lower rows.

BUG=332073

Review URL: https://codereview.chromium.org/163413006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251133 0039d316-1c4b-4281-b951-d872f2087c98

ui/keyboard/resources/elements/kb-row.html

@@ -55,6 +55,18 @@
       border-bottom-color: #393939;
       border-top-color: #717171;
     }
+
+    :host:nth-child(2) ::part(hint) {
+      color: #2C2C2C;
+    }
+
+    :host:nth-child(3) ::part(hint) {
+      color: #272727;
+    }
+
+    :host:nth-child(4) ::part(hint) {
+      color: #232323;
+    }
     </style>
     <content select="*"></content>
   </template>