[enh] landing page updates

searx/templates/index.html

 {% extends "base.html" %}
 {% block content %}
-<h1>searx</h1>
-<form method="post" action="">
-    <input type="text" name="q" />
-    <input type="submit" value="search" />
-</form>
+<div class="center">
+    <h1>searx</h1>
+    <form method="post" action="">
+        <input type="text" name="q" tabindex="1" />
+        <input type="submit" value="search" />
+    </form>
+</div>
 {% endblock %}