/* ============================================================
   Tetris — Warm theme matching Sudoku, iPad-first, senior-friendly
   ============================================================ */

:root {
  --bg: #faf7f2;
  --card: #ffffff;
  --text: #3d3229;
  --text-light: #8a7d72;
  --accent: #c9956b;
  --accent-light: #f5e6d3;
  --border: #d4c8bb;
  --border-thick: #8a7d72;
  --btn-bg: #f0e8de;
  --btn-active: #c9956b;
  --shadow: 0 2px 20px rgba(90, 70, 50, 0.08);
  --shadow-btn: 0 2px 8px rgba(90, 70, 50, 0.12);
  --radius: 18px;

  --board-bg: #2b2520;
  --board-grid: #3a322c;

  /* sizing tokens — overridden by media queries */
  --title-font: 30px;
  --stat-label-font: 14px;
  --stat-value-font: 28px;
  --ctrl-font: 36px;
  --ctrl-label-font: 22px;
  --text-btn-font: 18px;
  --ctrl-min-h: 70px;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-tap-highlight-color: transparent;
  -webkit-touch-callout: none;
  user-select: none;
}

html, body {
  height: 100%;
  height: 100dvh;
  overflow: hidden;
}

body {
  font-family: -apple-system, 'PingFang TC', 'Noto Sans TC', 'Helvetica Neue', sans-serif;
  background: var(--bg);
  color: var(--text);
}

.app {
  width: 100%;
  height: 100%;
  height: 100dvh;
  max-width: 1200px;
  margin: 0 auto;
  padding: 14px 16px;
  padding-top: calc(14px + env(safe-area-inset-top, 0px));
  padding-bottom: calc(12px + env(safe-area-inset-bottom, 0px));
  display: flex;
  flex-direction: column;
  gap: 10px;
}

/* --- Header --- */

.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
}

.title {
  font-size: var(--title-font);
  font-weight: 700;
  color: var(--text);
  letter-spacing: 4px;
}

.help-btn, .back-btn {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 2px solid var(--border);
  background: var(--card);
  color: var(--text-light);
  font-size: 22px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.2s;
  flex-shrink: 0;
}
.help-btn:active, .back-btn:active {
  border-color: var(--accent);
  color: var(--accent);
}

/* --- Status bar --- */

.status-bar {
  display: flex;
  align-items: center;
  justify-content: space-around;
  gap: 10px;
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 14px;
  box-shadow: var(--shadow);
  flex-shrink: 0;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  min-width: 60px;
}

.stat-label {
  font-size: var(--stat-label-font);
  color: var(--text-light);
  letter-spacing: 1px;
}

.stat-value {
  font-size: var(--stat-value-font);
  font-weight: 700;
  color: var(--text);
  line-height: 1;
}

.next-stat {
  min-width: 100px;
}

#next-canvas {
  background: transparent;
}

/* --- Play area --- */

.play-area {
  flex: 1 1 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-height: 0;
  align-items: center;
}

.board-wrap {
  position: relative;
  flex: 1 1 0;
  min-height: 0;
  /* board aspect ratio is 1:2 (10x20) */
  aspect-ratio: 1 / 2;
  max-width: 100%;
  max-height: 100%;
  background: var(--board-bg);
  border: 4px solid var(--border-thick);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

#board {
  display: block;
  width: 100%;
  height: 100%;
}

.overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(43, 37, 32, 0.7);
  backdrop-filter: blur(6px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s;
}

.overlay.show {
  opacity: 1;
  pointer-events: all;
}

.overlay-card {
  background: var(--card);
  border-radius: 22px;
  padding: 28px 36px;
  text-align: center;
  box-shadow: 0 10px 40px rgba(0,0,0,0.2);
  max-width: 80%;
}

.overlay-card h2 {
  font-size: 28px;
  margin-bottom: 8px;
  letter-spacing: 2px;
}

.overlay-sub {
  color: var(--text-light);
  font-size: 16px;
  margin-bottom: 18px;
}

/* --- Controls --- */

.controls {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 10px;
  flex-shrink: 0;
}

.row {
  display: flex;
  gap: 10px;
}

.ctrl-btn {
  flex: 1;
  min-height: var(--ctrl-min-h);
  border: none;
  border-radius: 16px;
  background: var(--card);
  color: var(--text);
  font-size: var(--ctrl-font);
  font-weight: 700;
  cursor: pointer;
  box-shadow: var(--shadow-btn);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.1s, background 0.15s;
  letter-spacing: 4px;
}

.ctrl-btn:active {
  transform: scale(0.95);
  background: var(--accent-light);
}

.ctrl-btn.rotate {
  background: var(--accent-light);
  color: var(--accent);
  font-size: calc(var(--ctrl-font) + 6px);
}

.ctrl-btn.drop {
  background: var(--accent);
  color: white;
  font-size: var(--ctrl-label-font);
  font-weight: 700;
}

.ctrl-btn.drop:active {
  background: #b6845c;
}

.ctrl-btn.wide {
  flex: 1;
}

.footer-row {
  margin-top: 4px;
}

.text-btn {
  flex: 1;
  padding: 12px 0;
  border: 2px solid var(--border);
  border-radius: 14px;
  background: var(--card);
  color: var(--text);
  font-size: var(--text-btn-font);
  font-weight: 600;
  cursor: pointer;
  letter-spacing: 2px;
  transition: all 0.15s;
}

.text-btn:active {
  transform: scale(0.96);
  background: var(--btn-bg);
}

.text-btn.primary {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

.text-btn.primary:active {
  background: #b6845c;
}

.primary-btn {
  padding: 14px 36px;
  border: none;
  border-radius: 28px;
  background: var(--accent);
  color: white;
  font-size: 20px;
  font-weight: 700;
  cursor: pointer;
  letter-spacing: 2px;
  box-shadow: 0 3px 12px rgba(201, 149, 107, 0.3);
}
.primary-btn:active { transform: scale(0.96); }

/* --- Modal --- */

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
  z-index: 100;
}

.modal-overlay.show {
  opacity: 1;
  pointer-events: all;
}

.modal {
  background: var(--card);
  border-radius: 28px;
  padding: 36px;
  text-align: center;
  max-width: 480px;
  width: 88%;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
}

.modal h2 {
  font-size: 30px;
  margin-bottom: 18px;
  color: var(--text);
}

.help-content {
  text-align: left;
  max-height: 60vh;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  margin-bottom: 20px;
}

.help-content h3 {
  font-size: 21px;
  margin: 18px 0 10px;
  color: var(--accent);
}
.help-content h3:first-child { margin-top: 0; }

.help-content p,
.help-content li {
  font-size: 18px;
  line-height: 1.7;
  color: var(--text);
}

.help-content ul {
  padding-left: 22px;
  margin-bottom: 14px;
}

/* =============================================================
   TABLET (iPad — any orientation)
   The 1:2 board wastes horizontal space if controls stack below it
   in portrait. Use a side-by-side layout for all tablet sizes so the
   board fills the full vertical height.
   ============================================================= */

@media (min-width: 700px) {
  :root {
    --title-font: 38px;
    --stat-label-font: 18px;
    --stat-value-font: 34px;
    --ctrl-font: 46px;
    --ctrl-label-font: 26px;
    --text-btn-font: 22px;
    --ctrl-min-h: 84px;
  }

  .app {
    padding: 14px 20px;
    padding-top: calc(14px + env(safe-area-inset-top, 0px));
    padding-bottom: calc(14px + env(safe-area-inset-bottom, 0px));
    padding-left: calc(20px + env(safe-area-inset-left, 0px));
    padding-right: calc(20px + env(safe-area-inset-right, 0px));
    gap: 12px;
  }

  .title { letter-spacing: 8px; }
  .help-btn, .back-btn { width: 58px; height: 58px; font-size: 28px; }

  .status-bar { padding: 12px 20px; }
  #next-canvas { width: 130px; height: 80px; }
  .next-stat { min-width: 130px; }

  .play-area {
    flex-direction: row;
    align-items: stretch;
    justify-content: center;
    gap: 24px;
  }

  .board-wrap {
    flex: 0 1 auto;
    height: 100%;
  }

  .controls {
    width: auto;
    min-width: 280px;
    max-width: 440px;
    justify-content: center;
    align-self: center;
    gap: 14px;
  }

  .ctrl-btn { border-radius: 20px; }
  .text-btn { padding: 14px 0; border-radius: 18px; }

  .overlay-card { padding: 36px 48px; }
  .overlay-card h2 { font-size: 36px; }
  .overlay-sub { font-size: 22px; }
  .primary-btn { font-size: 24px; padding: 16px 44px; }
}

/* =============================================================
   LARGE TABLET (iPad Pro 12.9")
   ============================================================= */

@media (min-width: 1024px) {
  :root {
    --title-font: 48px;
    --stat-label-font: 22px;
    --stat-value-font: 44px;
    --ctrl-font: 56px;
    --ctrl-label-font: 30px;
    --text-btn-font: 26px;
    --ctrl-min-h: 100px;
  }

  .controls { min-width: 360px; max-width: 500px; }
}

/* small phones */
@media (max-width: 380px) {
  :root {
    --title-font: 22px;
    --stat-label-font: 11px;
    --stat-value-font: 22px;
    --ctrl-font: 28px;
    --ctrl-label-font: 16px;
    --text-btn-font: 14px;
    --ctrl-min-h: 60px;
  }
  .app { padding: 10px 12px; gap: 8px; }
  .title { letter-spacing: 2px; }
  .next-stat { min-width: 70px; }
  #next-canvas { width: 70px; height: 50px; }
}