HTML indentation

• Before

<ul>
<li>level 1</li>
<li>level 2</li>
<ul>
<li>level 21</li>
<li>level 22</li>
</ul>
</ul>

• After

<ul>
    <li>level 1</li>
    <li>level 2</li>
    <ul>
        <li>level 21</li>
        <li>level 22</li>
    </ul>
</ul>

• Command
gvim output_file
gg
=G