Why doesn't my drop-down menu appear?-PHP Chinese Network Q&A

<!DOCTYPE html>

<html>

<head>

<title>Simon International Navigation</title>

</head>

<body>

<a href="">Hello, welcome to Simon</a>

</ div>

<a href="">Login</a>

<a href= "" >Free registration</a>

<a href="" >My Simon<i class="fa fa-arrow-down"></i>

<ul>

<li>sales</li>

</ul> ;

Site Navigation</a>

</div>

</body>

</html>

#*{margin: 0px; padding: 0px;}

.clear{clear: both;}

li {list-style: none;}

a{text-decoration: none; font-size: 15px; margin-left: 5px; color: #fff; line -height: 40px; display: inline-block;

padding-left: 10px;padding-right: 10px; position: relative; }

.header

{ background -color: #105599}

.headermain

{width: 1200px;margin: 0px auto; height: 40px;}

.headermain_l

{ float: left;}

.headermain_r

{

width: 550px;

float: right;

}

.headermain_r a:hover

{

background-color: #0A2743;

}

.headermain_r ul

{

height: 80px; width: 80px; position: absolute;

}

.headermain_r ul li

{

height: 30px;

}

Which teacher can help analyze it