:root {
  --paper: #f4ede2;
  --paper-2: #ece3d3;
  --card: rgba(255, 253, 248, 0.85);
  --accent: #c0392b;
  --accent-deep: #9c2b1f;
  --accent-soft: #f7e5e0;
  --accent-border: #e3bfb6;
  --ink: #26221d;
  --ink-soft: #4a423c;
  --text: #2f2925;
  --text-secondary: #6b6158;
  --text-muted: #98897b;
  --border: #dcd0c0;
  --border-light: #e8dfd1;
  --grid: rgba(110, 88, 64, 0.055);
  --success: #3d7a50;
  --success-light: #e8f1e9;
  --error: #b4452f;
  --shadow-sm: 0 1px 2px rgba(40, 32, 28, 0.07);
  --shadow-md: 0 10px 30px rgba(40, 32, 28, 0.12);
  --shadow-accent: 0 6px 18px rgba(192, 57, 43, 0.28);
  --radius: 6px;
  --radius-lg: 10px;
  --radius-pill: 999px;
  --font-display: 'Shippori Mincho', 'Noto Serif JP', serif;
  --font-sans: 'Zen Kaku Gothic New', 'Inter', -apple-system, system-ui, sans-serif;
  --font-jp: 'Zen Kaku Gothic New', 'Noto Sans JP', 'Hiragino Sans', sans-serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font-jp);
  font-size: 17px;
  color: var(--ink);
  background: var(--paper);
  background-image:
    radial-gradient(ellipse 1100px 420px at 50% -140px, rgba(255, 252, 244, 0.95), rgba(255, 252, 244, 0) 70%),
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: auto, 24px 24px, 24px 24px;
  background-position: 0 0;
  min-height: 100vh;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
::selection { background: var(--accent-soft); color: var(--accent-deep); }
a { text-decoration: none; }
a:hover { text-decoration: none; }

/* ---- Hero ---- */
.app-header {
  text-align: center;
  padding: 2.6rem 1.5rem 1.8rem;
  position: relative;
}
.app-header::after {
  content: '';
  display: block;
  width: 56px;
  height: 2px;
  background: var(--accent);
  margin: 1.2rem auto 0;
  box-shadow: 0 4px 0 var(--border-light);
}
.app-kicker {
  font-family: var(--font-sans);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.34em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1rem;
}
.app-seal {
  width: 60px; height: 60px;
  margin: 0 auto 1.1rem;
  background: var(--accent);
  color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-display);
  font-size: 2.15rem; font-weight: 800;
  box-shadow: var(--shadow-accent), inset 0 0 0 3px rgba(255, 255, 255, 0.18);
}
.app-header h1 {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--ink);
  margin-bottom: 0.6rem;
}
.app-header p {
  color: var(--text-secondary);
  font-size: 0.88rem;
  max-width: 500px;
  margin: 0 auto;
  line-height: 1.8;
  font-family: var(--font-sans);
}

.header-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.8rem;
  margin-top: 1.4rem;
  flex-wrap: wrap;
}
.flashcard-entry {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1.2rem;
  border-radius: var(--radius-pill);
  background: var(--accent);
  border: none;
  color: #fff;
  font-weight: 700;
  font-size: 0.9rem;
  box-shadow: var(--shadow-accent);
  transition: transform 0.12s ease, background 0.15s ease;
}
.flashcard-entry:hover {
  background: var(--accent-deep);
  transform: translateY(-1px);
}
.toggle-all {
  background: transparent;
  border: 1.5px solid var(--accent);
  color: var(--accent);
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: 0.85rem;
  padding: 0.5rem 1.2rem;
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: all 0.12s ease;
}
.toggle-all:hover {
  background: var(--accent-soft);
  border-color: var(--accent-deep);
}

/* ---- Accordion Grid ---- */
.lesson-grid {
  max-width: 820px;
  margin: 0 auto;
  padding: 0.9rem 1.5rem 3.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

/* ---- Lesson Row ---- */
.lesson-row {
  background: var(--card);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent-border);
  border-radius: var(--radius-lg);
  transition: border-color 0.2s, box-shadow 0.2s;
  overflow: hidden;
}
.lesson-row:hover {
  border-color: var(--border);
  box-shadow: var(--shadow-md);
}
.lesson-row.open {
  border-color: var(--accent-border);
  border-left-color: var(--accent);
  box-shadow: var(--shadow-md);
}
.lesson-row.coming-soon {
  border-left-color: var(--border);
  opacity: 0.6;
}

.lesson-header-bar {
  display: flex;
  align-items: center;
  padding: 1.15rem 1.3rem;
  cursor: pointer;
  user-select: none;
  gap: 1.1rem;
  transition: background 0.15s;
  width: 100%;
  font: inherit;
  color: inherit;
  background: transparent;
  border: none;
  text-align: left;
}
.lesson-header-bar:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}
.lesson-header-bar:hover {
  background: rgba(192, 57, 43, 0.04);
}
.lesson-row.coming-soon .lesson-header-bar {
  cursor: default;
}
.lesson-row.coming-soon .lesson-header-bar:hover {
  background: none;
}

.lesson-num {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 800;
  min-width: 2.7rem;
  height: 2.7rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
  background: var(--accent-soft);
  border: 1px solid var(--accent-border);
  color: var(--accent-deep);
  line-height: 1;
  transition: all 0.2s ease;
}
.lesson-row.open .lesson-num,
.lesson-row:not(.coming-soon):hover .lesson-num {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  box-shadow: 0 2px 8px rgba(192, 57, 43, 0.25);
}
.lesson-row.coming-soon .lesson-num {
  background: var(--paper-2);
  border-color: var(--border);
  color: var(--text-muted);
}

.lesson-info {
  flex: 1;
  min-width: 0;
}
.lesson-title-jp { font-weight: 700; font-size: 1.08rem; color: var(--ink); margin-bottom: 0.12rem; }
.lesson-title-jp ruby { ruby-align: center; }
.lesson-title-jp rt { font-size: 0.5em; color: var(--text-muted); }
.lesson-title-en {
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-family: var(--font-sans);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lesson-chevron {
  width: 1.9rem;
  height: 1.9rem;
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  color: var(--text-secondary);
  border: 1px solid var(--border);
  background: var(--card);
  border-radius: var(--radius-pill);
  transition: transform 0.25s ease, color 0.2s, border-color 0.2s, background 0.2s;
}
.lesson-row.open .lesson-chevron {
  transform: rotate(180deg);
  color: var(--accent);
  border-color: var(--accent-border);
  background: var(--accent-soft);
}
.lesson-row.coming-soon .lesson-chevron {
  display: none;
}

.lesson-status-badge {
  font-size: 0.68rem;
  font-family: var(--font-sans);
  font-weight: 700;
  letter-spacing: 0.05em;
  padding: 0.22em 0.7em;
  border-radius: var(--radius-pill);
  border: 1px solid;
  flex-shrink: 0;
  background: transparent;
}
.badge-ready {
  color: var(--success);
  border-color: rgba(61, 122, 80, 0.35);
  background: var(--success-light);
}
.badge-soon {
  color: var(--text-muted);
  border-color: var(--border);
  background: var(--paper-2);
}

/* ---- Section List inside accordion ---- */
.section-list {
  display: block;
  border-top: 1px dashed var(--border);
  padding: 0.7rem 1.3rem 1.1rem;
  background: rgba(244, 237, 226, 0.45);
}
.section-list[hidden] {
  display: none;
}

.section-item {
  display: flex;
  align-items: center;
  padding: 0.7rem 0.9rem;
  margin: 0.3rem 0;
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--ink);
  transition: background 0.15s, border-color 0.15s, transform 0.15s;
  border: 1px solid transparent;
  gap: 0.9rem;
  cursor: pointer;
}
.section-item:hover {
  background: var(--card);
  border-color: var(--border-light);
  transform: translateX(2px);
}
.section-item.soon {
  opacity: 0.4;
  cursor: default;
  pointer-events: none;
}

.sec-num {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--accent);
  min-width: 2.1rem;
  height: 2.1rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
  background: var(--card);
  border: 1px solid var(--border-light);
  transition: all 0.15s ease;
}
.section-item:hover .sec-num {
  background: var(--accent-soft);
  border-color: var(--accent-border);
  color: var(--accent-deep);
}
.section-item.soon .sec-num {
  color: var(--text-muted);
  background: var(--paper-2);
  border-color: var(--border);
}

.sec-topic {
  font-weight: 600;
  font-size: 0.95rem;
}
.sec-topic-en {
  font-size: 0.78rem;
  color: var(--text-secondary);
  font-family: var(--font-sans);
  margin-left: 0.5rem;
}

.sec-arrow {
  margin-left: auto;
  color: var(--text-muted);
  font-size: 0.9rem;
  flex-shrink: 0;
  transition: transform 0.15s ease, color 0.15s ease;
}
.section-item:hover .sec-arrow {
  transform: translateX(3px);
  color: var(--accent);
}

/* ---- Footer ---- */
.app-footer {
  text-align: center;
  padding: 2.2rem;
  color: var(--text-muted);
  font-size: 0.78rem;
  font-family: var(--font-sans);
  border-top: 1px solid var(--border-light);
  max-width: 820px;
  margin: 0 auto;
}

/* The catalog is also the small-screen landing page. Keep the lesson rows
   readable without making the title compete with three separate controls. */
@media (max-width: 600px) {
  body { font-size: 16px; }
  .app-header { padding: 1.9rem 1rem 1.25rem; }
  .app-kicker { font-size: 0.6rem; letter-spacing: 0.24em; margin-bottom: 0.85rem; }
  .app-seal { width: 56px; height: 56px; margin-bottom: 0.9rem; font-size: 2rem; }
  .app-header h1 {
    font-size: clamp(1.55rem, 8.2vw, 1.9rem);
    letter-spacing: 0.02em;
    white-space: nowrap;
  }
  .app-header p { font-size: 0.82rem; line-height: 1.75; }
  .header-actions { gap: 0.55rem; margin-top: 1.1rem; }
  .flashcard-entry, .toggle-all { min-height: 44px; padding: 0.55rem 1rem; }

  .lesson-grid { gap: 0.55rem; padding: 0.5rem 0.75rem 2.5rem; }
  .lesson-header-bar { gap: 0.65rem; padding: 0.85rem 0.85rem; }
  .lesson-num { min-width: 2.55rem; height: 2.55rem; font-size: 1.2rem; }
  .lesson-title-jp {
    min-width: 0;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-size: 1rem;
  }
  .lesson-title-en { font-size: 0.72rem; margin-top: 0.1rem; }
  .lesson-status-badge { font-size: 0.62rem; padding: 0.2em 0.55em; }

  .section-list { padding: 0.45rem 0.7rem 0.8rem; }
  .section-item { align-items: flex-start; gap: 0.65rem; padding: 0.65rem 0.55rem; }
  .sec-num { flex-shrink: 0; }
  .sec-topic { min-width: 0; line-height: 1.4; }
  .sec-topic-en { display: block; margin: 0.1rem 0 0; font-size: 0.72rem; line-height: 1.35; }
  .sec-arrow { padding-top: 0.2rem; }
  .app-footer { padding: 1.8rem 1rem; }
}

@media (max-width: 360px) {
  .app-header h1 { font-size: 1.58rem; }
  .lesson-grid { padding-inline: 0.6rem; }
  .lesson-header-bar { gap: 0.45rem; padding-inline: 0.7rem; }
  .lesson-status-badge { min-width: 1.65rem; padding-inline: 0; text-align: center; font-size: 0; }
  .lesson-status-badge::before { font-size: 0.75rem; }
  .badge-ready::before { content: "✓"; }
  .badge-soon::before { content: "…"; }
}