/* ============================================================
   Learn Japanese — styles.css
   Japanese aesthetic: clean whites, warm red accent,
   subtle ink-brush feel
   ============================================================ */

/* ---- Reset & Base ---- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --accent:     #c0392b;   /* Japanese red */
  --accent-lt:  #e74c3c;
  --bg:         #fafaf8;
  --surface:    #ffffff;
  --border:     #e8e4df;
  --text:       #2c2c2c;
  --text-muted: #888;
  --shadow:     0 2px 8px rgba(0,0,0,.08);
  --radius:     10px;
  --font-jp:    'Noto Sans JP', 'Hiragino Kaku Gothic ProN',
                'Yu Gothic', sans-serif;
  --font-ui:    -apple-system, BlinkMacSystemFont, 'Segoe UI',
                Roboto, sans-serif;
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font-ui);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ---- Header ---- */
header {
  background: var(--surface);
  border-bottom: 2px solid var(--accent);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow);
}

header h1 {
  text-align: center;
  font-family: var(--font-jp);
  font-size: 1.5rem;
  font-weight: 700;
  padding: 0.75rem 1rem 0.25rem;
  color: var(--accent);
  letter-spacing: 0.04em;
}

header h1 span {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 400;
  margin-left: 0.5rem;
  font-family: var(--font-ui);
}

/* ---- Tab Bar ---- */
.tab-bar {
  display: flex;
  overflow-x: auto;
  scrollbar-width: none;
  gap: 2px;
  padding: 0 0.5rem;
}

.tab-bar::-webkit-scrollbar { display: none; }

.tab-btn {
  flex-shrink: 0;
  background: none;
  border: none;
  border-bottom: 3px solid transparent;
  padding: 0.6rem 1rem;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-muted);
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s;
  white-space: nowrap;
}

.tab-btn:hover {
  color: var(--accent-lt);
}

.tab-btn.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
  font-weight: 700;
}

/* ---- Main Content ---- */
main {
  flex: 1;
  max-width: 1100px;
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem 1rem 3rem;
}

/* ---- Tab Panels ---- */
.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
  animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ---- Section Header ---- */
.section-header {
  margin-bottom: 1.25rem;
}

.section-header h2 {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text);
}

.section-header h3 {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text);
}

.subtitle {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: 0.25rem;
}

.action-btn {
  margin-top: 0.75rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 6px;
  padding: 0.4rem 1rem;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}

.action-btn:hover {
  background: var(--accent-lt);
}

.row-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.sub-section-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 1rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--border);
}

/* ============================================================
   FLIP CARDS — Hiragana
   ============================================================ */
.card-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.65rem;
  max-width: 520px;
}

/* Invisible spacer to keep 5-column alignment */
.flip-card.spacer-card {
  pointer-events: none;
  visibility: hidden;
}

.row-spacer {
  grid-column: 1 / -1;
  height: 0.25rem;
}

.flip-card {
  perspective: 600px;
  cursor: pointer;
  aspect-ratio: 1;
}

.flip-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: var(--radius);
}

.flip-card.flipped .flip-inner {
  transform: rotateY(180deg);
}

.flip-front,
.flip-back {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  box-shadow: var(--shadow);
}

.flip-front {
  background: var(--surface);
  border: 1.5px solid var(--border);
  font-family: var(--font-jp);
  font-size: clamp(1.4rem, 4vw, 1.9rem);
  color: var(--text);
}

.flip-back {
  background: var(--accent);
  color: #fff;
  font-size: clamp(0.75rem, 2.5vw, 1rem);
  font-weight: 600;
  letter-spacing: 0.05em;
  transform: rotateY(180deg);
}

/* Hover lift effect */
.flip-card:not(.spacer-card):hover .flip-front,
.flip-card:not(.spacer-card):hover .flip-back {
  filter: brightness(0.97);
}

/* ============================================================
   PHRASE CARDS — Greetings / Phrases / Time
   ============================================================ */
.phrase-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 0.85rem;
}

.phrase-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  box-shadow: var(--shadow);
  transition: transform 0.15s, box-shadow 0.15s;
}

.phrase-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(0,0,0,.1);
}

.phrase-card .jp {
  font-family: var(--font-jp);
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.3rem;
  line-height: 1.4;
}

.phrase-card .romaji {
  font-size: 0.9rem;
  color: var(--accent);
  font-style: italic;
  margin-bottom: 0.2rem;
}

.phrase-card .en {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ============================================================
   NUMBERS TABLE
   ============================================================ */
.number-table-wrap {
  overflow-x: auto;
}

.number-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
  background: var(--surface);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

.number-table thead {
  background: var(--accent);
  color: #fff;
}

.number-table th {
  padding: 0.65rem 1rem;
  text-align: left;
  font-weight: 600;
  letter-spacing: 0.04em;
  font-size: 0.85rem;
}

.number-table td {
  padding: 0.6rem 1rem;
  border-bottom: 1px solid var(--border);
  vertical-align: middle;
}

.number-table tbody tr:last-child td {
  border-bottom: none;
}

.number-table tbody tr:nth-child(even) {
  background: #f9f7f5;
}

.number-table tbody tr:hover {
  background: #fef0ee;
}

/* Japanese numerals in table */
.number-table td:nth-child(2) {
  font-family: var(--font-jp);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--accent);
}

.number-table td:nth-child(3) {
  font-family: var(--font-jp);
  font-size: 1rem;
}

/* ---- Footer ---- */
footer {
  text-align: center;
  padding: 1.5rem 1rem;
  font-size: 0.82rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  background: var(--surface);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 600px) {
  header h1 {
    font-size: 1.2rem;
  }

  .tab-btn {
    padding: 0.5rem 0.7rem;
    font-size: 0.82rem;
  }

  main {
    padding: 1rem 0.75rem 2rem;
  }

  .card-grid {
    grid-template-columns: repeat(5, 1fr);
    gap: 0.4rem;
    max-width: 100%;
  }

  .flip-front {
    font-size: 1.3rem;
  }

  .phrase-grid {
    grid-template-columns: 1fr;
  }

  .number-table th,
  .number-table td {
    padding: 0.5rem 0.65rem;
    font-size: 0.85rem;
  }

  .number-table td:nth-child(2) {
    font-size: 1rem;
  }
}

@media (max-width: 360px) {
  .flip-front {
    font-size: 1.1rem;
  }
  .flip-back {
    font-size: 0.65rem;
  }
}

/* ============================================================
   AUDIO PRONUNCIATION
   ============================================================ */
.phrase-card { position: relative; }

.speak-btn {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  padding: 0.2rem 0.3rem;
  border-radius: 4px;
  color: var(--text-muted);
  transition: color 0.15s, background 0.15s;
}
.speak-btn:hover {
  color: var(--accent);
  background: rgba(192, 57, 43, 0.08);
}
.phrase-card .speak-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
}
.speak-cell {
  text-align: center;
  width: 2.5rem;
}

/* Speaking states */
.phrase-card.speaking {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(192, 57, 43, 0.25);
}
.number-table tbody tr.speaking {
  background: #fef0ee !important;
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}
.flip-card.speaking .flip-front,
.flip-card.speaking .flip-back {
  box-shadow: 0 0 0 3px var(--accent);
}
.speak-btn.speaking {
  color: var(--accent);
  animation: pulse-speaker 0.6s ease-in-out infinite alternate;
}
@keyframes pulse-speaker {
  from { transform: scale(1);   opacity: 1;   }
  to   { transform: scale(1.2); opacity: 0.7; }
}