diff --git a/colors.html b/colors.html
index 6896359..fa6c5d5 100644
--- a/colors.html
+++ b/colors.html
@@ -14,6 +14,10 @@
     width="800"
     xmlns="http://www.w3.org/2000/svg"
 >
+<style>
+circle { stroke-width: 2px; }
+circle:hover { stroke: black; }
+</style>
 </svg>
 
 <script>