fix: tweak styles for mobile

frontend/src/routes/index.tsx

@@ -319,8 +319,8 @@ export default component$(() => {
           <span class="subtitle">
             sentence highlights based on their significance to the document
           </span>
-          <a href="./about" class="about-link">How it works →</a>
         </h1>
+        <a href="./about" class="about-link text-sm">How it works →</a>
         <div class="controls">
           <label for="model-select">Model:</label>
           <select