diff --git a/docs/usage/index.html b/docs/usage/index.html
index e9242e6c..845ae007 100644
--- a/docs/usage/index.html
+++ b/docs/usage/index.html
@@ -106,7 +106,7 @@ <h1>Light/dark mode demonstration</h1>
     <section>
       <h2>User selection</h2>
       <p>This section will change based on user preference.</p>
-      <button onclick="setMode(event, 'mode-system')">System</button>
+      <button onclick="setMode(event, 'mode-system')" class="active">System</button>
       <button onclick="setMode(event, 'mode-light')">Light</button>
       <button onclick="setMode(event, 'mode-dark')">Dark</button>
     </section>