<html> <meta chartset=utf-8> <title>Test Reference</title> <link rel="author" title="Florian Rivoal" href="https://florian.rivoal.net"> <style> html { writing-mode: vertical-rl; } body { writing-mode: vertical-rl; width: 0; height: 0; } html::before { content: "This text must be vertical."; } html::after { content: "This text must be horizontal."; display: block; writing-mode: horizontal-tb; } </style> <body></body>