/* BahnDeutsch — teaching sample. Light UI only, self-hosted, no frameworks. */

.bd-teaching-method {
  --tm-bg: #f3f5fb;
  --tm-paper: #ffffff;
  --tm-ink: #152033;
  --tm-muted: #5c6b80;
  --tm-faint: #7b8aa0;
  --tm-line: rgba(53, 72, 110, 0.12);
  --tm-accent: #3d4ee8;
  --tm-accent-2: #5b4ee0;
  --tm-accent-soft: rgba(61, 78, 232, 0.1);
  --tm-ok: #0f9f6e;
  --tm-shadow: 0 18px 40px rgba(21, 32, 51, 0.08);
  --tm-radius: 22px;
  --tm-width: 1120px;
  --tm-ease: 180ms ease;
  box-sizing: border-box;
  margin: 0 auto;
  color: var(--tm-ink);
  background:
    radial-gradient(900px 420px at 100% -10%, rgba(61, 78, 232, 0.08), transparent 58%),
    radial-gradient(700px 380px at -8% 80%, rgba(91, 78, 224, 0.06), transparent 52%),
    var(--tm-bg);
  font-family: var(--bd-font-body);
  line-height: 1.75;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  min-height: 40vh;
  overflow-x: hidden;
  color-scheme: light;
}

.bd-teaching-method *,
.bd-teaching-method *::before,
.bd-teaching-method *::after {
  box-sizing: border-box;
}

.bd-teaching-method :where(h1, h2, h3) {
  font-family: var(--bd-font-display);
  letter-spacing: -0.03em;
  line-height: 1.25;
  color: var(--tm-ink);
}

.bd-teaching-method a {
  color: inherit;
  text-decoration: none;
}

.bd-teaching-method img,
.bd-teaching-method svg,
.bd-teaching-method video {
  display: block;
  max-width: 100%;
}

.bd-teaching-method .tm-wrap {
  width: min(100% - 1.5rem, var(--tm-width));
  margin-inline: auto;
}

.bd-teaching-method #bd-teaching-method,
.bd-teaching-method #bd-teaching-videos {
  scroll-margin-top: 5.5rem;
}

/* Bar */
.bd-teaching-method .tm-bar {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(243, 245, 251, 0.88);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--tm-line);
}

.bd-teaching-method .tm-bar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 4.25rem;
}

.bd-teaching-method .tm-brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  min-width: 0;
}

.bd-teaching-method .tm-brand__mark {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 0.85rem;
  display: grid;
  place-items: center;
  flex-shrink: 0;
  color: #fff;
  background: linear-gradient(145deg, #4f46e5, #3730a3);
  font-family: var(--bd-font-display);
  font-weight: 800;
  font-size: 0.78rem;
  letter-spacing: -0.04em;
}

.bd-teaching-method .tm-brand__name {
  margin: 0;
  font-weight: 800;
  font-size: 0.95rem;
}

.bd-teaching-method .tm-brand__sub {
  margin: 0.1rem 0 0;
  color: var(--tm-faint);
  font-size: 0.78rem;
}

.bd-teaching-method .tm-chip {
  display: none;
  align-items: center;
  gap: 0.45rem;
  margin: 0;
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  border: 1px solid var(--tm-line);
  background: var(--tm-paper);
  color: var(--tm-muted);
  font-size: 0.8rem;
  font-weight: 700;
}

.bd-teaching-method .tm-chip__dot {
  width: 0.5rem;
  height: 0.5rem;
  border-radius: 50%;
  background: var(--tm-ok);
  box-shadow: 0 0 0 4px rgba(15, 159, 110, 0.16);
}

/* Hero */
.bd-teaching-method .tm-hero {
  padding: 1.75rem 0 0.5rem;
}

.bd-teaching-method .tm-hero__grid {
  display: grid;
  gap: 1.5rem;
  align-items: start;
}

.bd-teaching-method .tm-kicker {
  display: inline-flex;
  margin: 0 0 0.85rem;
  padding: 0.28rem 0.7rem;
  border-radius: 999px;
  background: var(--tm-accent-soft);
  color: var(--tm-accent);
  font-size: 0.78rem;
  font-weight: 800;
}

.bd-teaching-method .tm-kicker--soft {
  background: #fff;
  border: 1px solid var(--tm-line);
}

.bd-teaching-method .tm-hero h1 {
  margin: 0;
  font-size: clamp(1.7rem, 4.4vw, 2.7rem);
  font-weight: 850;
  max-width: 16ch;
}

.bd-teaching-method .tm-lead {
  margin: 0.9rem 0 0;
  max-width: 42ch;
  color: var(--tm-muted);
  font-size: 1.02rem;
  line-height: 1.9;
}

.bd-teaching-method .tm-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 1.35rem;
}

.bd-teaching-method .tm-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-height: 2.9rem;
  padding: 0 1.15rem;
  border-radius: 999px;
  font-weight: 800;
  font-size: 0.92rem;
  transition: transform var(--tm-ease), box-shadow var(--tm-ease), background-color var(--tm-ease);
}

.bd-teaching-method .tm-btn--solid {
  color: #fff;
  background: var(--tm-accent);
  box-shadow: 0 10px 22px rgba(61, 78, 232, 0.28);
}

.bd-teaching-method .tm-btn--solid:hover {
  transform: translateY(-1px);
}

.bd-teaching-method .tm-btn--ghost {
  color: var(--tm-ink);
  background: #fff;
  border: 1px solid var(--tm-line);
}

.bd-teaching-method .tm-btn:focus-visible {
  outline: 3px solid rgba(61, 78, 232, 0.35);
  outline-offset: 2px;
}

/* Player */
.bd-teaching-method .tm-player {
  background: var(--tm-paper);
  border: 1px solid var(--tm-line);
  border-radius: var(--tm-radius);
  box-shadow: var(--tm-shadow);
  overflow: hidden;
}

.bd-teaching-method .tm-player__head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 1rem 1.05rem 0.85rem;
}

.bd-teaching-method .tm-player__title {
  margin: 0 0 0.2rem;
  font-size: 1.05rem;
}

.bd-teaching-method .tm-player__lead {
  margin: 0;
  color: var(--tm-muted);
  font-size: 0.86rem;
  line-height: 1.7;
}

.bd-teaching-method .tm-badge {
  flex-shrink: 0;
  padding: 0.28rem 0.65rem;
  border-radius: 999px;
  background: var(--tm-accent-soft);
  color: var(--tm-accent);
  font-size: 0.75rem;
  font-weight: 800;
  white-space: nowrap;
}

.bd-teaching-method .player-shell {
  margin: 0 0.7rem;
  padding: 0.35rem;
  border-radius: 16px;
  background: #0f172a;
}

.bd-teaching-method .player-stage {
  position: relative;
  overflow: hidden;
  border-radius: 12px;
  background: #0f172a;
}

.bd-teaching-method .player {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #000;
  outline: none;
}

.bd-teaching-method .player-overlay {
  position: absolute;
  inset: 0;
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.7rem;
  padding: 1.25rem;
  background: rgba(15, 23, 42, 0.55);
  color: #fff;
  text-align: center;
}

.bd-teaching-method .player-overlay[hidden] {
  display: none;
}

.bd-teaching-method .player-overlay-msg {
  margin: 0;
  max-width: 26rem;
  font-size: 0.92rem;
  line-height: 1.7;
}

.bd-teaching-method .player-spinner {
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  border: 3px solid rgba(255, 255, 255, 0.28);
  border-top-color: #fff;
  animation: tm-spin 0.8s linear infinite;
}

.bd-teaching-method .player-spinner[hidden],
.bd-teaching-method .player-retry[hidden] {
  display: none;
}

.bd-teaching-method .player-retry {
  appearance: none;
  border: 0;
  border-radius: 999px;
  padding: 0.55rem 1rem;
  background: #fff;
  color: #0f172a;
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}

@keyframes tm-spin {
  to { transform: rotate(360deg); }
}

.bd-teaching-method .tm-player__note,
.bd-teaching-method .video-error {
  margin: 0.75rem 1.05rem 1rem;
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--tm-faint);
}

.bd-teaching-method .video-error {
  color: #b42318;
  background: #fef3f2;
  border-radius: 12px;
  padding: 0.7rem 0.85rem;
}

.bd-teaching-method .video-error[hidden] {
  display: none;
}

/* Sections */
.bd-teaching-method .tm-section {
  padding: 2.4rem 0 0.4rem;
}

.bd-teaching-method .tm-head {
  max-width: 40rem;
  margin-bottom: 1.25rem;
}

.bd-teaching-method .tm-head h2 {
  margin: 0;
  font-size: clamp(1.25rem, 3vw, 1.75rem);
}

.bd-teaching-method .tm-intro {
  margin: 0.7rem 0 0;
  color: var(--tm-muted);
  line-height: 1.9;
}

.bd-teaching-method .tm-cards,
.bd-teaching-method .tm-path,
.bd-teaching-method .tm-next {
  display: grid;
  gap: 0.8rem;
}

.bd-teaching-method .tm-card,
.bd-teaching-method .tm-path__item,
.bd-teaching-method .tm-next__card,
.bd-teaching-method .tm-faq__item {
  background: var(--tm-paper);
  border: 1px solid var(--tm-line);
  border-radius: 18px;
}

.bd-teaching-method .tm-card {
  padding: 1.15rem 1.1rem 1.2rem;
}

.bd-teaching-method .tm-card:hover {
  border-color: rgba(61, 78, 232, 0.28);
}

.bd-teaching-method .tm-card__icon {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 0.8rem;
  display: grid;
  place-items: center;
  margin-bottom: 0.85rem;
  color: #fff;
  background: linear-gradient(145deg, var(--tm-accent), var(--tm-accent-2));
}

.bd-teaching-method .tm-card h3,
.bd-teaching-method .tm-path__item h3 {
  margin: 0 0 0.4rem;
  font-size: 1rem;
}

.bd-teaching-method .tm-card p,
.bd-teaching-method .tm-path__item p {
  margin: 0;
  color: var(--tm-muted);
  font-size: 0.92rem;
  line-height: 1.8;
}

.bd-teaching-method .tm-path__item {
  display: grid;
  grid-template-columns: 2.5rem 1fr;
  gap: 0.85rem;
  padding: 1rem 1.05rem;
  list-style: none;
}

.bd-teaching-method .tm-path {
  list-style: none;
  margin: 0;
  padding: 0;
}

.bd-teaching-method .tm-path__num {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 0.8rem;
  display: grid;
  place-items: center;
  color: #fff;
  background: linear-gradient(145deg, var(--tm-accent), var(--tm-accent-2));
  font-weight: 800;
}

.bd-teaching-method .tm-faq {
  max-width: 42rem;
}

.bd-teaching-method .tm-faq__list {
  display: grid;
  gap: 0.55rem;
}

.bd-teaching-method .tm-faq__item summary {
  cursor: pointer;
  list-style: none;
  padding: 0.95rem 1.05rem;
  font-weight: 800;
  font-size: 0.95rem;
}

.bd-teaching-method .tm-faq__item summary::-webkit-details-marker {
  display: none;
}

.bd-teaching-method .tm-faq__item p {
  margin: 0;
  padding: 0 1.05rem 1rem;
  color: var(--tm-muted);
  font-size: 0.92rem;
  line-height: 1.85;
}

.bd-teaching-method .tm-next__card {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  padding: 1rem 1.05rem;
  transition: transform var(--tm-ease), border-color var(--tm-ease);
}

.bd-teaching-method .tm-next__card:hover {
  transform: translateY(-2px);
  border-color: rgba(61, 78, 232, 0.28);
}

.bd-teaching-method .tm-next__card strong {
  font-size: 0.98rem;
}

.bd-teaching-method .tm-next__card span {
  color: var(--tm-muted);
  font-size: 0.86rem;
  line-height: 1.7;
}

.bd-teaching-method .tm-promise {
  display: grid;
  gap: 1.25rem;
}

.bd-teaching-method .tm-promise__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.55rem;
}

.bd-teaching-method .tm-promise__list li {
  display: grid;
  grid-template-columns: 1.25rem 1fr;
  gap: 0.65rem;
  align-items: start;
  padding: 0.85rem 1rem;
  background: var(--tm-paper);
  border: 1px solid var(--tm-line);
  border-radius: 14px;
  color: var(--tm-ink);
  font-size: 0.92rem;
  font-weight: 700;
  line-height: 1.7;
}

.bd-teaching-method .tm-promise__list svg {
  margin-top: 0.15rem;
  color: var(--tm-ok);
}

@media (min-width: 720px) {
  .bd-teaching-method .tm-chip { display: inline-flex; }
  .bd-teaching-method .tm-cards { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .bd-teaching-method .tm-cards--three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .bd-teaching-method .tm-path { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .bd-teaching-method .tm-path__item { grid-template-columns: 1fr; }
  .bd-teaching-method .tm-next { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .bd-teaching-method .tm-promise {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: start;
  }
}

.bd-teaching-method .tm-foot {
  margin-top: 2.5rem;
  padding: 1.6rem 0 2rem;
  border-top: 1px solid var(--tm-line);
  text-align: center;
}

.bd-teaching-method .tm-foot__brand {
  margin: 0;
  font-weight: 800;
}

.bd-teaching-method .tm-foot__tag,
.bd-teaching-method .tm-foot__note {
  margin: 0.35rem 0 0;
  color: var(--tm-muted);
  font-size: 0.88rem;
}

.bd-teaching-method .tm-foot__note {
  color: var(--tm-faint);
  font-size: 0.8rem;
}

/* Reveal must stay visible without JS (page cache / delayed scripts). */
.bd-teaching-method .bd-teaching-method__reveal {
  opacity: 1;
  transform: none;
}

.bd-teaching-method .bd-teaching-method__reveal.is-visible {
  animation: tm-rise 0.5s ease;
}

@keyframes tm-rise {
  from { transform: translateY(10px); }
  to { transform: none; }
}

@media (min-width: 980px) {
  .bd-teaching-method .tm-hero__grid {
    grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
    gap: 2.2rem;
    align-items: center;
  }

  .bd-teaching-method .tm-hero {
    padding-top: 2.4rem;
  }
}

@media (max-width: 719px) {
  .bd-teaching-method .tm-brand__sub { display: none; }
  .bd-teaching-method .tm-actions { flex-direction: column; }
  .bd-teaching-method .tm-btn { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  .bd-teaching-method *,
  .bd-teaching-method *::before,
  .bd-teaching-method *::after {
    animation: none !important;
    transition: none !important;
  }
}