body{margin:0;font-family:Arial,sans-serif;background:#111827;color:#f3f4f6}header{background:#1f2937;padding:30px;text-align:center}nav a{color:#60a5fa;text-decoration:none;margin:0 12px}main{max-width:900px;margin:40px auto;padding:0 20px}.card{background:#1f2937;padding:24px;border-radius:12px;margin-bottom:20px;box-shadow:0 2px 10px rgba(0,0,0,.3)}footer{text-align:center;padding:20px;color:#9ca3af}