Update 900 colors for accessibility

Author: wenzeng4

scss/colors/palette.scss

@@ -27,7 +27,7 @@ $ux-blue-500: $ux-blue;
 $ux-blue-600: #155B99;
 $ux-blue-700: #0D4473;
 $ux-blue-800: #083054;
-$ux-blue-900: #032847;
+$ux-blue-900: #00192E;
 
 $ux-gray-100: #F9F9F9;
 $ux-gray-200: #F1F1F1;
@@ -47,7 +47,7 @@ $ux-green-500: $ux-green;
 $ux-green-600: #47A13B;
 $ux-green-700: #297021;
 $ux-green-800: #1A5313;
-$ux-green-900: #0E4207;
+$ux-green-900: #062902;
 
 $ux-orange-100: #FDEAD2;
 $ux-orange-200: #FCDFB9;
@@ -57,7 +57,7 @@ $ux-orange-500: $ux-orange;
 $ux-orange-600: #E18C28;
 $ux-orange-700: #AE6608;
 $ux-orange-800: #7D4A06;
-$ux-orange-900: #653B05;
+$ux-orange-900: #3D2200;
 
 $ux-red-100: #F0D9D9;
 $ux-red-200: #E8C5CB;
@@ -67,7 +67,7 @@ $ux-red-500: $ux-red;
 $ux-red-600: #C71F1F;
 $ux-red-700: #B11B1B;
 $ux-red-800: #9B1818;
-$ux-red-900: #851414;
+$ux-red-900: #470404;
 
 $ux-yellow-100: #FDF6D2;
 $ux-yellow-200: #FCF1B9;
@@ -77,7 +77,7 @@ $ux-yellow-500: $ux-yellow;
 $ux-yellow-600: #E1C228;
 $ux-yellow-700: #AE9208;
 $ux-yellow-800: #7D6906;
-$ux-yellow-900: #655505;
+$ux-yellow-900: #3D3300;
 
 $ux-purple-100: #EAE6FA;
 $ux-purple-200: #DCD7F1;
@@ -87,4 +87,4 @@ $ux-purple-500: $ux-purple;
 $ux-purple-600: #5642A6;
 $ux-purple-700: #42308C;
 $ux-purple-800: #34227A;
-$ux-purple-900: #201259;
+$ux-purple-900: #120640;