03. Color Palette

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>First Steps Into PHP</title>
    <style>
        div{
            display: inline-block;
            width: 150px;
            padding: 2px;
            margin: 5px;
        }
    </style>
</head>
<body>
<?php
for ($red = 0; $red <= 255; $red += 51){
    for ($green = 0; $green <= 255; $green += 51){
        for ($blue = 0; $blue <= 255; $blue += 51){
            $color = "rgb($red, $green, $blue)";
            echo "<div style='background: $color'>$color</div>\n";
        }
    }
}
?>
</body>
</html>