/* Integration-only navigation; lesson visuals and interactions are unchanged. */
header .site-return, .tetromino-lesson header .site-return, .angle-lesson header .site-return {
  flex-shrink: 0; white-space: nowrap; font-size: 14px; text-decoration: none;
}
@media (max-width: 640px) {
  header .site-return .return-grade { display: none; }
  header .site-return { padding: 5px 3px !important; font-size: 12px !important; }
}