Center page numbers on list_something

/close #38

static/css/style.css

@@ -33,10 +33,9 @@ input[type="file"] {
 }
 
 .centered {
-    margin: 0 auto;
-    max-width: 300px;
+    text-align: center;
 }
 
 .centered > a {
-    margin: 10px;
+    margin: 8px;
 }