:root {
  --ink: #1c1915;
  --muted: #5c5348;
  --paper: #f4efe4;
  --paper-2: #ebe4d4;
  --card: #fffaf1;
  --line: #d7ccb8;
  --vermilion: #b42318;
  --vermilion-soft: #f3d3c7;
  --indigo: #2a4058;
  --green: #2f6b4f;
  --shadow: 0 12px 40px rgba(36, 28, 18, 0.08);
  --radius: 18px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: "Noto Sans Bengali", "Noto Sans JP", sans-serif;
  background:
    radial-gradient(1200px 500px at 10% -10%, #fff7ea 0%, transparent 55%),
    linear-gradient(180deg, var(--paper) 0%, #e7dfcf 100%);
  color: var(--ink);
  min-height: 100vh;
}
a { color: inherit; }
button, input { font: inherit; }
.sr-only, .skip {
  position: absolute;
  left: -999px;
  top: 0;
}
.skip:focus {
  left: 12px;
  top: 12px;
  background: #fff;
  padding: 8px 12px;
  z-index: 20;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  gap: 16px;
  align-items: center;
  justify-content: space-between;
  padding: 14px 22px;
  background: rgba(244, 239, 228, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
}
.brand {
  display: flex;
  gap: 12px;
  align-items: center;
  text-decoration: none;
}
.brand-mark {
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  border: 2px solid var(--vermilion);
  color: var(--vermilion);
  font-family: "Zen Old Mincho", "Noto Sans JP", serif;
  font-weight: 700;
  border-radius: 8px;
  transform: rotate(-8deg);
}
.brand-text { display: flex; flex-direction: column; line-height: 1.2; }
.brand-text strong {
  font-family: "Zen Old Mincho", "Noto Sans JP", serif;
  font-size: 1.15rem;
}
.brand-text small { color: var(--muted); font-size: 0.78rem; }
.search {
  display: flex;
  gap: 8px;
  flex: 1;
  max-width: 520px;
}
.search input {
  flex: 1;
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 999px;
  padding: 10px 16px;
}
.search button, .btn {
  border: 0;
  background: var(--ink);
  color: #fff;
  border-radius: 999px;
  padding: 10px 16px;
  cursor: pointer;
}
.btn.ghost {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--line);
}
.btn.small { padding: 7px 12px; font-size: 0.9rem; }

#app { max-width: 1120px; margin: 0 auto; padding: 28px 18px 80px; }
.site-foot {
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
  padding: 0 18px 28px;
}

.hero {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 22px;
  margin-bottom: 28px;
}
.hero-card, .panel, .lesson-card, .track, .pdf-shell {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.hero-card { padding: 28px; }
.hero h1 {
  font-family: "Zen Old Mincho", "Noto Sans JP", serif;
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  margin: 0 0 8px;
}
.kicker {
  color: var(--vermilion);
  letter-spacing: 0.12em;
  font-size: 0.78rem;
  font-weight: 700;
}
.hero p { color: var(--muted); line-height: 1.7; }
.stats {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 18px;
}
.stat {
  background: var(--paper-2);
  border-radius: 999px;
  padding: 6px 12px;
  font-size: 0.88rem;
}
.particle-board { padding: 22px; }
.particle-board h2, .section-title {
  margin: 0 0 12px;
  font-size: 1.05rem;
}
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  min-width: 64px;
  padding: 8px 10px;
  border-radius: 14px;
  background: #fff;
  border: 1px solid var(--line);
  text-decoration: none;
  cursor: pointer;
}
.chip b {
  font-family: "Zen Old Mincho", "Noto Sans JP", serif;
  font-size: 1.35rem;
}
.chip span { font-size: 0.72rem; color: var(--muted); }
.chip:hover, .chip.active { border-color: var(--vermilion); background: var(--vermilion-soft); }

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 12px;
}
.lesson-card {
  padding: 16px;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-height: 132px;
  transition: transform 0.15s ease, border-color 0.15s ease;
}
.lesson-card:hover { transform: translateY(-3px); border-color: var(--indigo); }
.num {
  font-family: "Zen Old Mincho", "Noto Sans JP", serif;
  color: var(--vermilion);
  font-size: 1.4rem;
}
.jp { font-family: "Noto Sans JP", sans-serif; font-weight: 700; }
.bn { color: var(--muted); font-size: 0.9rem; line-height: 1.45; }

.lesson-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: flex-start;
  margin-bottom: 16px;
}
.tabs {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}
.tab {
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 999px;
  padding: 8px 14px;
  cursor: pointer;
}
.tab.active {
  background: var(--ink);
  color: #fff;
  border-color: var(--ink);
}

.toolbar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  align-items: center;
  margin-bottom: 12px;
}
.pdf-shell {
  padding: 12px;
  overflow: auto;
  max-height: calc(100vh - 260px);
  min-height: 360px;
}
.pdf-shell canvas {
  display: block;
  margin: 0 auto;
  width: min(100%, 860px);
  height: auto;
  background: #fff;
  border-radius: 8px;
}
.page-ind { color: var(--muted); font-size: 0.9rem; }
.source-switch { display: flex; gap: 8px; flex-wrap: wrap; }

.track-list { display: grid; gap: 10px; }
.track {
  padding: 14px 16px;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
  align-items: center;
}
.track audio { width: min(420px, 100%); }
.now-playing { border-color: var(--green); background: #eef7f1; }

.result {
  padding: 14px 16px;
  border: 1px solid var(--line);
  background: var(--card);
  border-radius: 14px;
  text-decoration: none;
  display: block;
  margin-bottom: 10px;
}

.empty {
  padding: 28px;
  text-align: center;
  color: var(--muted);
}

@media (max-width: 860px) {
  .hero { grid-template-columns: 1fr; }
  .topbar { flex-direction: column; align-items: stretch; }
  .search { max-width: none; }
  .lesson-head { flex-direction: column; }
  .track { grid-template-columns: 1fr; }
}