js updates

step1-02/exercise/index.html

@@ -11,15 +11,12 @@
         <button class="submit">Add</button>
       </div>
       <nav class="filter">
-        <button class="active">all</button>
+        <button class="selected">all</button>
         <button>active</button>
         <button>completed</button>
       </nav>
     </header>
-    <main>
-      <ul class="todos">
-        <li>Todo 1</li>
-      </ul>
-    </main>
+    <main></main>
+    <footer></footer>
   </body>
 </html>