Untitled

<?php

class StroopTest
{
    private const COLORS = ['red', 'blue', 'green', 'yellow', 'lime', 'magenta', 'black', 'gold', 'gray', 'tomato'];

    public function generate(int $lines = 5): string
    {
        $html = '';
        for ($i = 0; $i < $lines; $i++) {
            $data = $this->generateData();
            $html .= '<p>';
            $html .= $this->generateRow(data: $data);
            $html .= '</p>';
        }
        return $html;
    }

    private function generateRow(array $data): string
    {
        $html = '';
        foreach ($data as $color => $word) {
            $html .= "<span style='margin-left:5px; color: $color'>$word</span>";
        }
        return $html;
    }

    private function generateData(): array
    {
        $sources = self::COLORS;
        shuffle($sources);
        $count = count($sources);
        $partCount = $count / 2;
        $parts = [
            array_slice($sources, 0, $partCount),
            array_slice($sources, $partCount, $count)
        ];
        shuffle($parts);
        [$colors, $words] = $parts;
        $data = array_combine($words, $colors);
        return array_slice($data, 0, 5);
    }
}

?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Stroop effect</title>
</head>
<body>
<?= (new StroopTest())->generate() ?>
</body>
</html>