.classroom-page {
  --classroom-red: #b8202b;
  --classroom-ink: #171717;
  --classroom-muted: #5f6268;
  --classroom-line: #c9c5bc;
  --classroom-paper: #f8f5ef;
  --classroom-green: #132319;
  --classroom-gold: #b4924c;
  color: var(--classroom-ink);
}

.classroom-hero,
.classroom-source,
.classroom-tools,
.classroom-directory,
.classroom-notes {
  padding-inline: clamp(20px, 5vw, 72px);
}

.classroom-hero {
  padding-top: clamp(52px, 8vw, 112px);
  padding-bottom: clamp(36px, 6vw, 76px);
  border-bottom: 1px solid var(--classroom-line);
}

.classroom-kicker,
.classroom-category-kicker {
  margin: 0 0 12px;
  color: var(--classroom-red);
  font-size: 0.8rem;
  font-weight: 900;
  text-transform: uppercase;
}

.classroom-hero h1 {
  margin: 0;
  font-family: "Noto Serif JP", serif;
  font-size: clamp(3rem, 8vw, 7.5rem);
  line-height: 0.96;
  letter-spacing: 0;
}

.classroom-source {
  display: grid;
  grid-template-columns: minmax(0, 0.75fr) minmax(280px, 1.25fr);
  gap: clamp(28px, 5vw, 72px);
  align-items: start;
  padding-top: clamp(42px, 6vw, 76px);
  padding-bottom: clamp(42px, 6vw, 76px);
  background: var(--classroom-ink);
  color: #fff;
}

.classroom-source h2,
.classroom-category h2,
.classroom-group h3 {
  margin: 0;
  font-family: "Noto Serif JP", serif;
  letter-spacing: 0;
}

.classroom-source h2 {
  font-size: clamp(2rem, 4vw, 4rem);
  line-height: 1.08;
  text-wrap: balance;
}

.classroom-source-copy p {
  margin: 0;
  color: #e5e2dc;
  font-size: 1.05rem;
  line-height: 1.85;
}

.classroom-official-link {
  display: inline-flex;
  align-items: center;
  min-height: 46px;
  margin-top: 24px;
  padding: 10px 0;
  border-bottom: 3px solid var(--classroom-red);
  color: #fff;
  font-weight: 900;
  text-decoration: none;
}

.classroom-official-link:hover,
.classroom-official-link:focus-visible {
  color: #ffb6bc;
}

.classroom-tools {
  padding-top: clamp(28px, 4vw, 52px);
  padding-bottom: clamp(34px, 5vw, 60px);
  border-bottom: 1px solid var(--classroom-line);
  background: rgb(246 242 234 / 72%);
  color: var(--classroom-ink);
}

.classroom-controls {
  max-width: 760px;
}

.classroom-control label {
  display: flex;
  margin-bottom: 8px;
  color: var(--classroom-muted);
  font-size: 0.8rem;
  font-weight: 900;
}

.classroom-search {
  width: 100%;
  min-height: 48px;
  padding: 11px 14px;
  border: 1px solid var(--classroom-line);
  border-radius: 0;
  background: rgb(255 255 255 / 74%);
  color: var(--classroom-ink);
  font: inherit;
}

.classroom-search::placeholder {
  color: var(--classroom-muted);
}

.classroom-filter-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  margin-top: 26px;
}

.classroom-filter {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  min-height: 44px;
  padding: 9px 20px;
  border: 1px solid var(--classroom-line);
  border-radius: 999px;
  background: rgb(255 255 255 / 48%);
  color: var(--classroom-ink);
  cursor: pointer;
  font: inherit;
  font-size: 0.83rem;
  font-weight: 800;
  line-height: 1.3;
}

.classroom-filter span:first-child {
  font-family: "Noto Serif JP", serif;
  font-size: 1.02rem;
}

.classroom-filter.is-active,
.classroom-filter:hover,
.classroom-filter:focus-visible {
  border-color: var(--classroom-red);
  background: var(--classroom-ink);
  color: #fff;
  outline: none;
}

.classroom-belt-filter {
  min-width: 142px;
  border-width: 2px;
  border-radius: 6px;
  box-shadow: 0 3px 9px rgb(23 23 23 / 7%);
}

.classroom-belt-filter.is-yellow {
  border-color: #d0a700;
  background: #f3cf2f;
  color: #171717;
}

.classroom-belt-filter.is-orange {
  border-color: #c85a08;
  background: #e87920;
  color: #171717;
}

.classroom-belt-filter.is-green {
  border-color: #176b35;
  background: #258247;
  color: #fff;
}

.classroom-belt-filter.is-blue {
  border-color: #174c9c;
  background: #2867b7;
  color: #fff;
}

.classroom-belt-filter.is-brown {
  border-color: #63381f;
  background: #805033;
  color: #fff;
}

.classroom-belt-filter:hover,
.classroom-belt-filter:focus-visible,
.classroom-belt-filter.is-active {
  border-color: var(--classroom-ink);
  box-shadow: inset 0 0 0 2px #fff, 0 4px 12px rgb(23 23 23 / 15%);
  filter: saturate(1.05) brightness(0.96);
}

.classroom-directory {
  padding-top: clamp(32px, 5vw, 72px);
  padding-bottom: 72px;
}

.classroom-category {
  scroll-margin-top: 96px;
  padding-top: clamp(42px, 6vw, 76px);
}

.classroom-category:first-child {
  padding-top: 0;
}

.classroom-category-head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding-bottom: 16px;
  border-bottom: 4px solid var(--classroom-ink);
}

.classroom-category h2 {
  font-size: clamp(2.35rem, 5vw, 5rem);
}

.classroom-category-roman {
  color: var(--classroom-red);
  font-weight: 900;
}

.classroom-group {
  scroll-margin-top: 96px;
  padding: 28px 0 18px;
  border-bottom: 1px dashed var(--classroom-line);
}

.classroom-group-head {
  display: flex;
  gap: 14px;
  align-items: center;
  margin-bottom: 10px;
}

.classroom-group h3 {
  font-size: clamp(1.4rem, 2.5vw, 2rem);
}

.classroom-group-roman {
  color: var(--classroom-muted);
  font-size: 0.82rem;
  font-weight: 800;
}

.classroom-play-all {
  min-height: 32px;
  margin-left: auto;
  padding: 4px 9px;
  border: 1px solid var(--classroom-ink);
  border-radius: 0;
  background: transparent;
  color: var(--classroom-ink);
  cursor: pointer;
  font: inherit;
  font-size: 0.8rem;
  font-weight: 900;
}

.classroom-technique-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(238px, 1fr));
  gap: 10px;
}

.classroom-technique {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-width: 0;
  min-height: 76px;
  padding: 12px 10px 12px 16px;
  overflow: hidden;
  border: 1px solid rgb(23 23 23 / 18%);
  border-radius: 6px;
  background: rgb(255 255 255 / 68%);
  box-shadow: 0 4px 14px rgb(23 23 23 / 5%);
}

.classroom-technique::before {
  position: absolute;
  inset: 0 auto 0 0;
  width: 3px;
  background: var(--classroom-red);
  content: "";
}

.classroom-technique[hidden] {
  display: none;
}

.classroom-technique.is-playing {
  border-color: var(--classroom-red);
  background: #fff;
  box-shadow: 0 6px 18px rgb(184 32 43 / 12%);
}

.classroom-technique-number {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

.classroom-technique-copy {
  min-width: 0;
}

.classroom-technique h4 {
  margin: 0;
  font-family: "Noto Serif JP", serif;
  font-size: 1.22rem;
  line-height: 1.25;
  overflow-wrap: anywhere;
}

.classroom-technique-reading {
  display: block;
  margin-top: 4px;
  color: var(--classroom-muted);
  font-family: "Noto Sans HK", sans-serif;
  font-size: 0.76rem;
  font-weight: 800;
  line-height: 1.35;
  overflow-wrap: anywhere;
}

.classroom-technique-actions {
  display: flex;
  flex: 0 0 auto;
  gap: 6px;
  align-items: center;
}

.classroom-play {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  padding: 0;
  border: 1px solid rgb(23 23 23 / 28%);
  border-radius: 50%;
  background: #fff;
  color: var(--classroom-ink);
  cursor: pointer;
  font-size: 0.95rem;
}

.classroom-play:hover,
.classroom-play:focus-visible,
.classroom-play[aria-pressed="true"] {
  border-color: var(--classroom-red);
  background: var(--classroom-red);
  color: #fff;
  outline: 2px solid rgb(184 32 43 / 18%);
  outline-offset: 2px;
}

.classroom-video-link {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 30px;
  border: 1px solid var(--classroom-red);
  border-radius: 5px;
  background: var(--classroom-red);
  color: #fff;
  font-size: 0.78rem;
  text-decoration: none;
}

.classroom-video-link:hover,
.classroom-video-link:focus-visible {
  border-color: var(--classroom-ink);
  background: var(--classroom-ink);
  color: #fff;
  outline: 2px solid rgb(23 23 23 / 16%);
  outline-offset: 2px;
}

.classroom-empty {
  padding: 60px 0;
  color: var(--classroom-muted);
  text-align: center;
}

.classroom-notes {
  padding-top: 32px;
  padding-bottom: 48px;
  border-top: 1px solid var(--classroom-line);
  background: var(--classroom-paper);
  color: var(--classroom-muted);
  font-size: 0.9rem;
  line-height: 1.75;
}

.classroom-notes p {
  max-width: 980px;
  margin: 0 0 8px;
}

@media (max-width: 900px) {
  .classroom-source {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 620px) {
  .classroom-hero {
    padding-top: 48px;
    padding-bottom: 32px;
  }

  .classroom-source h2 {
    font-size: 1.75rem;
  }

  .classroom-filter-list {
    gap: 10px 12px;
  }

  .classroom-filter {
    min-height: 40px;
    padding: 8px 16px;
  }

  .classroom-group-head {
    flex-wrap: wrap;
  }

  .classroom-play-all {
    margin-left: 0;
  }

  .classroom-technique-grid {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .classroom-page {
    scroll-behavior: auto;
  }
}