coding a form appropriately
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>ログイン|入稿管理支援システム</title>
<link rel="stylesheet" type="text/css" href="asset/css/styles.css" />
</head>
<header>
<p><a href="index.html">Hpscript</a></p>
<nav>
<p>入稿管理支援システム</p>
</nav>
</header>
<body>
<div id="content">
<h1>ログイン</h1>
<form action="cgi-bin/hoge.cgi" method="post">
<p>
ユーザーID:<input type="text" name="login_id" size="20">
</p>
<p>
パスワード:<input type="text" name="password" size="20">
</p>
<p>
<input type="submit" value="ログイン">
</p>
</form>
</div>
</body>
</html>

In a sense this is already fine, but i want to it center.
#content {
margin-top:100px;
text-align:center;
}
#content h1{
font-size: 16px;
margin-bottom:40px;
}

well, finally reaching the point.