修改题目列表和首页的样式

template/oj/index.html

@@ -90,7 +90,7 @@
 <body>
 <div id="header">
     <span id="name">qduoj</span>
-    <a href="/problems/">题目</a>&nbsp;&nbsp;<a href="#">比赛</a>&nbsp;&nbsp;<a href="#">小组</a>
+    <a href="/problems/">题目</a>&nbsp;&nbsp;<a href="/contests/">比赛</a>&nbsp;&nbsp;<a href="#">小组</a>
 </div>
 
 <div id="fullpage">