Lời giải:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Two Inline Frames</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<div class="container">
<iframe src="frame1.html"></iframe>
<iframe src="frame2.html"></iframe>
</div>
</body>
</html>