body.error404, body.error404 #menu, body.error404 nav {
    background: #e74c3c
}

/* body.error404 .btn rule removed Phase 4 Axe B C5 — the `btn`
 * class no longer exists in 404.php (replaced by tw:* utilities). */

body.error404 img.travolta {
    position: fixed;
    bottom: 0;
    height: 60vh
}