Feat/improve styles (#1868)

* improve css

* fix table

* fix write page

* improve header nav

* fix menu

* fix menu

* fix menu

* add flex grid system

* fix

* fix flex

* fix draft version

* using main html element to replace div

* improve css

* add input type number

* fix custom-fields

* fix screen

admin/user.php

@@ -4,7 +4,7 @@ include 'header.php';
 include 'menu.php';
 ?>
 
-<div class="main">
+<main class="main">
     <div class="body container">
         <?php include 'page-title.php'; ?>
         <div class="row typecho-page-main" role="form">
@@ -13,7 +13,7 @@ include 'menu.php';
             </div>
         </div>
     </div>
-</div>
+</main>
 
 <?php
 include 'copyright.php';