css_box_model.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>CSS Box Model</title>
    <link rel="stylesheet" href="css/box_model.css">
</head>
<body>
    <h1><strong><a href="https://en.wikipedia.org/wiki/Visible_spectrum">Visible Spectrum Wavelengths</a></strong></h1>
    <div id="red">620-750 nm</div>
    <div id="orange">590-620 nm</div>
    <div id="yellow">570-590 nm</div>
    <div id="green">495-570 nm</div>
    <div id="blue">450-495 nm</div>
    <div id="purple">380-450 nm</div>
</body>
</html>