Drop-down navigation menu has a fixed format:
<ul>
<li><a href="">首页</a></li>
<ul>
<ul>
<li> <a href=""> picture effects </a>
<li> <a href=""> music effects </a>
<li> <a href=""> video effects </ a >
<li> <a href=""> text effects </a>
</ ul>
</ul>
I will just add a background css files, as Style drop-down navigation menus can be set according to their preferences.
