Untitled

<!DOCTYPE html>
<html>
<head>
	<title>CSS練習</title>
        <meta charset="UTF-8">
        <style>
		html, body{
			height:100%;
			background:red;
		}
		.a{
			height:30%;
                	background:orange;
            	}
		p{font-size:15px;}
        </style>
</head>
<body>
	<div class="a">
            <p>15pxの文字。</p>
        </div>
</body>
</html>