:root {
  color-scheme: dark;
  --bg-color: #070a12;
  --bg-glow-primary: rgba(213, 0, 249, 0.12);
  --bg-glow-secondary: rgba(0, 229, 255, 0.08);
  --panel-bg: rgba(13, 20, 36, 0.75);
  --border-color: rgba(0, 229, 255, 0.25);
  --panel-shadow: rgba(0, 0, 0, 0.4);
  --accent-cyan: #00e5ff;
  --accent-purple: #d500f9;
  --accent-yellow: #ffd600;
  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --heading-color: #ffffff;
  --canvas-card-bg: rgba(0, 0, 0, 0.4);
  --subtle-border: rgba(255, 255, 255, 0.08);
  --board-shell-bg: #000000;
  --board-glow: rgba(0, 229, 255, 0.2);
  --board-shadow: rgba(0, 0, 0, 0.6);
  --overlay-bg: rgba(7, 10, 18, 0.86);
  --overlay-title-glow: rgba(0, 229, 255, 0.7);
  --start-gradient: linear-gradient(135deg, #00b4d8, #7b2cbf);
  --start-shadow: rgba(0, 229, 255, 0.4);
  --start-shadow-hover: rgba(0, 229, 255, 0.7);
  --focus-ring: rgba(255, 255, 255, 0.9);
  --stat-bg: rgba(0, 0, 0, 0.35);
  --stat-border: rgba(255, 255, 255, 0.06);
  --button-bg: rgba(255, 255, 255, 0.07);
  --button-border: rgba(255, 255, 255, 0.18);
  --button-hover-bg: rgba(0, 229, 255, 0.18);
  --button-hover-text: #ffffff;
  --primary-gradient: linear-gradient(135deg, #00b4d8, #0077b6);
  --primary-text: #ffffff;
  --danger-text: #ff5252;
  --danger-border: rgba(255, 82, 82, 0.4);
  --kbd-bg: rgba(255, 255, 255, 0.12);
  --kbd-border: rgba(255, 255, 255, 0.25);
  --kbd-text: #ffffff;
  --touch-bg: rgba(255, 255, 255, 0.12);
  --touch-border: rgba(0, 229, 255, 0.3);
  --touch-text: #ffffff;
  --touch-shadow: rgba(0, 0, 0, 0.3);
  --touch-active-bg: rgba(0, 229, 255, 0.35);
  --hard-drop-bg: rgba(0, 229, 255, 0.25);
  --controller-bg: rgba(7, 10, 18, 0.95);
  --controller-border: rgba(0, 229, 255, 0.25);
  --controller-shadow: rgba(0, 0, 0, 0.5);
  --font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
}

:root[data-theme="day"] {
  color-scheme: light;
  --bg-color: #e8eef6;
  --bg-glow-primary: rgba(79, 70, 229, 0.12);
  --bg-glow-secondary: rgba(8, 145, 178, 0.13);
  --panel-bg: rgba(255, 255, 255, 0.9);
  --border-color: rgba(3, 105, 161, 0.42);
  --panel-shadow: rgba(15, 23, 42, 0.16);
  --accent-cyan: #0369a1;
  --accent-purple: #6d28d9;
  --accent-yellow: #854d0e;
  --text-main: #0f172a;
  --text-muted: #475569;
  --heading-color: #0f172a;
  --canvas-card-bg: #dbe5f0;
  --subtle-border: rgba(15, 23, 42, 0.18);
  --board-shell-bg: #cbd8e6;
  --board-glow: rgba(3, 105, 161, 0.2);
  --board-shadow: rgba(15, 23, 42, 0.22);
  --overlay-bg: rgba(241, 245, 249, 0.9);
  --overlay-title-glow: rgba(3, 105, 161, 0.22);
  --start-gradient: linear-gradient(135deg, #0284c7, #5b21b6);
  --start-shadow: rgba(3, 105, 161, 0.28);
  --start-shadow-hover: rgba(3, 105, 161, 0.42);
  --focus-ring: #172554;
  --stat-bg: rgba(226, 232, 240, 0.86);
  --stat-border: rgba(15, 23, 42, 0.16);
  --button-bg: #e2e8f0;
  --button-border: rgba(15, 23, 42, 0.25);
  --button-hover-bg: #bae6fd;
  --button-hover-text: #0c4a6e;
  --primary-gradient: linear-gradient(135deg, #0284c7, #0369a1);
  --primary-text: #ffffff;
  --danger-text: #b91c1c;
  --danger-border: rgba(185, 28, 28, 0.45);
  --kbd-bg: #d8e1ec;
  --kbd-border: rgba(15, 23, 42, 0.3);
  --kbd-text: #0f172a;
  --touch-bg: #e2e8f0;
  --touch-border: rgba(3, 105, 161, 0.5);
  --touch-text: #0f172a;
  --touch-shadow: rgba(15, 23, 42, 0.18);
  --touch-active-bg: #7dd3fc;
  --hard-drop-bg: #bae6fd;
  --controller-bg: rgba(241, 245, 249, 0.97);
  --controller-border: rgba(3, 105, 161, 0.38);
  --controller-shadow: rgba(15, 23, 42, 0.2);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  user-select: none;
  -webkit-user-select: none;
}

body {
  background-color: var(--bg-color);
  background-image: 
    radial-gradient(circle at 50% 20%, var(--bg-glow-primary) 0%, transparent 60%),
    radial-gradient(circle at 80% 80%, var(--bg-glow-secondary) 0%, transparent 50%);
  color: var(--text-main);
  font-family: var(--font-family);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow-x: hidden;
  padding: 10px;
}

/* Header */
header {
  text-align: center;
  margin-bottom: 12px;
}

h1 {
  font-size: 26px;
  letter-spacing: 4px;
  color: var(--heading-color);
  text-shadow: 0 0 12px var(--accent-cyan);
  text-transform: uppercase;
}

h1 span {
  color: var(--accent-cyan);
}

.subtitle {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 1px;
  margin-top: 2px;
}

/* Game Wrapper Layout */
.game-container {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 16px;
  max-width: 900px;
  width: 100%;
}

/* Panels */
.panel {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 14px;
  backdrop-filter: blur(10px);
  box-shadow: 0 10px 30px var(--panel-shadow);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.left-panel {
  width: 150px;
}

.right-panel {
  width: 170px;
}

.panel-section {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.panel-title {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--text-muted);
  letter-spacing: 1.5px;
  margin-bottom: 6px;
}

/* Canvases */
.canvas-card {
  background: var(--canvas-card-bg);
  border: 1px solid var(--subtle-border);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

#hold-canvas {
  width: 110px;
  height: 90px;
}

#next-canvas {
  width: 110px;
  height: 220px;
}

/* Center Board Canvas */
.board-container {
  position: relative;
  background: var(--board-shell-bg);
  border: 2px solid var(--border-color);
  border-radius: 12px;
  box-shadow: 
    0 0 25px var(--board-glow),
    0 15px 40px var(--board-shadow);
  overflow: hidden;
}

#tetris-canvas {
  display: block;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.start-overlay {
  position: absolute;
  inset: 0;
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  background: var(--overlay-bg);
  backdrop-filter: blur(3px);
}

.start-overlay[hidden] {
  display: none;
}

.start-title {
  color: var(--accent-cyan);
  font-size: 28px;
  font-weight: 900;
  letter-spacing: 5px;
  text-shadow: 0 0 18px var(--overlay-title-glow);
}

.start-form {
  width: min(230px, calc(100% - 32px));
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 8px;
}

.start-form label {
  color: var(--text-muted);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1.5px;
  text-align: center;
  text-transform: uppercase;
}

.start-form input {
  width: 100%;
  padding: 11px 12px;
  border: 1px solid var(--button-border);
  border-radius: 8px;
  background: var(--stat-bg);
  color: var(--text-main);
  font: 600 15px var(--font-family);
  text-align: center;
  user-select: text;
  -webkit-user-select: text;
}

.start-form input:focus-visible {
  border-color: var(--accent-cyan);
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

.start-form input[aria-invalid="true"] {
  border-color: var(--danger-text);
}

.name-error {
  min-height: 15px;
  color: var(--danger-text);
  font-size: 11px;
  text-align: center;
}

.start-button {
  width: 100%;
  padding: 15px 28px;
  border: 2px solid var(--accent-cyan);
  border-radius: 10px;
  background: var(--start-gradient);
  box-shadow: 0 0 24px var(--start-shadow);
  color: var(--primary-text);
  cursor: pointer;
  font: 900 22px var(--font-family);
  letter-spacing: 3px;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.start-button:disabled {
  cursor: not-allowed;
  filter: grayscale(0.75);
  opacity: 0.55;
}

.start-button:disabled:hover {
  box-shadow: 0 0 24px var(--start-shadow);
  outline: none;
  transform: none;
}

.start-button:hover,
.start-button:focus-visible {
  box-shadow: 0 0 34px var(--start-shadow-hover);
  outline: 3px solid var(--focus-ring);
  outline-offset: 3px;
  transform: scale(1.04);
}

.start-button:active {
  transform: scale(0.98);
}

.start-hint {
  color: var(--text-muted);
  font-size: 12px;
  letter-spacing: 1px;
}

/* Stat Counters */
.stat-box {
  width: 100%;
  background: var(--stat-bg);
  border: 1px solid var(--stat-border);
  border-radius: 8px;
  padding: 8px 10px;
  text-align: center;
}

.stat-label {
  font-size: 10px;
  text-transform: uppercase;
  color: var(--text-muted);
  letter-spacing: 1px;
}

.stat-value {
  font-size: 18px;
  font-weight: 800;
  color: var(--accent-yellow);
  margin-top: 2px;
  font-variant-numeric: tabular-nums;
}

.stat-value.cyan {
  color: var(--accent-cyan);
}

.stat-value.purple {
  color: var(--accent-purple);
}

.leaderboard {
  width: 100%;
  padding-top: 2px;
}

.leaderboard .panel-title {
  text-align: center;
}

.leaderboard-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
  list-style-position: inside;
  color: var(--text-muted);
  font-size: 10px;
  font-variant-numeric: tabular-nums;
}

.leaderboard-list li:not(.leaderboard-empty) {
  display: grid;
  grid-template-columns: 14px minmax(0, 1fr) auto;
  gap: 3px;
  align-items: center;
}

.leaderboard-list li:not(.leaderboard-empty)::before {
  content: counter(list-item) ".";
  color: var(--accent-purple);
  font-weight: 800;
}

.leaderboard-list span {
  overflow: hidden;
  color: var(--text-main);
  text-overflow: ellipsis;
  white-space: nowrap;
}

.leaderboard-list strong {
  color: var(--accent-yellow);
  font-weight: 800;
}

.leaderboard-empty {
  list-style: none;
  text-align: center;
}

/* Controls & Buttons */
.speed-control {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 8px;
  width: 100%;
}

.speed-control label {
  color: var(--text-muted);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
}

.speed-control select {
  min-width: 58px;
  height: 34px;
  padding: 4px 24px 4px 9px;
  border: 1px solid var(--button-border);
  border-radius: 6px;
  background-color: var(--button-bg);
  color: var(--text-main);
  cursor: pointer;
  font: 700 12px var(--font-family);
}

.speed-control select:focus-visible {
  border-color: var(--accent-cyan);
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

.btn-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 100%;
}

.btn {
  background: var(--button-bg);
  border: 1px solid var(--button-border);
  border-radius: 6px;
  color: var(--text-main);
  font-size: 11px;
  font-weight: 600;
  padding: 8px 12px;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.btn:hover {
  background: var(--button-hover-bg);
  border-color: var(--accent-cyan);
  color: var(--button-hover-text);
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(0);
}

.btn:focus-visible,
.touch-btn:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

.btn.primary {
  background: var(--primary-gradient);
  border: none;
  color: var(--primary-text);
}

.btn.muted {
  color: var(--danger-text);
  border-color: var(--danger-border);
}

/* Controls Guide */
.controls-guide {
  font-size: 10px;
  color: var(--text-muted);
  line-height: 1.6;
  width: 100%;
}

.controls-guide table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 4px;
}

.controls-guide td {
  padding: 2px 0;
}

.controls-guide kbd {
  background: var(--kbd-bg);
  border: 1px solid var(--kbd-border);
  border-radius: 3px;
  padding: 1px 4px;
  font-family: monospace;
  font-size: 9px;
  color: var(--kbd-text);
}

/* Mobile Virtual Touch Controls */
.touch-controls {
  display: none;
  width: 100%;
  max-width: 480px;
  margin-top: 14px;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  touch-action: manipulation;
}

.touch-dpad {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(2, 1fr);
  gap: 8px;
}

.touch-actions {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
}

.touch-btn {
  background: var(--touch-bg);
  border: 1px solid var(--touch-border);
  border-radius: 12px;
  color: var(--touch-text);
  font-size: 18px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: center;
  touch-action: manipulation;
  cursor: pointer;
  box-shadow: 0 4px 12px var(--touch-shadow);
}

.touch-btn:active {
  background: var(--touch-active-bg);
  transform: scale(0.95);
}

.touch-btn span {
  font-size: 11px;
  font-weight: 700;
}

.touch-btn-hard-drop {
  grid-column: span 2;
  background: var(--hard-drop-bg);
}

/* Responsive Breakpoints - Mobile No-Scroll Viewport with Bottom Docked Controls */
@media (max-width: 768px) {
  html, body {
    height: 100vh;
    height: 100dvh;
    overflow: hidden;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
  }

  header {
    padding: 4px 8px;
    margin: 0;
    text-align: center;
    flex-shrink: 0;
  }

  header h1 {
    font-size: 15px;
    margin: 0;
    letter-spacing: 2px;
  }

  header .subtitle {
    display: none;
  }

  .game-container {
    flex: 1;
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: 2px 4px;
    overflow: hidden;
    min-height: 0;
    width: 100%;
    box-sizing: border-box;
  }

  .left-panel, .right-panel {
    width: 68px;
    max-width: 72px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    padding: 4px;
    background: transparent;
    border: none;
    box-shadow: none;
  }

  .panel-section {
    margin-bottom: 2px;
  }

  .panel-title {
    font-size: 9px;
    letter-spacing: 1px;
    margin-bottom: 2px;
  }

  .stat-box {
    margin-bottom: 3px;
    padding: 2px 4px;
    width: 100%;
    box-sizing: border-box;
  }

  .stat-label {
    font-size: 8px;
    margin-bottom: 1px;
  }

  .stat-value {
    font-size: 11px;
  }

  .leaderboard-list {
    gap: 2px;
    font-size: 8px;
  }

  .leaderboard-list li:not(.leaderboard-empty) {
    grid-template-columns: 10px minmax(0, 1fr);
    gap: 1px;
  }

  .leaderboard-list strong {
    grid-column: 2;
  }

  .btn-group {
    display: flex;
    flex-direction: column;
    gap: 4px;
    width: 100%;
  }

  .speed-control {
    grid-template-columns: 1fr;
    gap: 2px;
  }

  .speed-control label {
    font-size: 8px;
    text-align: center;
  }

  .speed-control select {
    width: 100%;
    min-width: 0;
    height: 32px;
    padding: 2px 4px;
    font-size: 11px;
    text-align: center;
  }

  .btn-group .btn {
    padding: 4px 6px;
    font-size: 10px;
    border-radius: 6px;
  }

  .controls-guide {
    display: none;
  }

  .board-container {
    border-radius: 8px;
    flex-shrink: 0;
  }

  /* Fixed Bottom Touch Controls */
  .touch-controls {
    display: grid;
    flex-shrink: 0;
    width: 100%;
    max-width: 480px;
    margin: 0 auto;
    padding: 4px 8px max(10px, env(safe-area-inset-bottom));
    background: var(--controller-bg);
    border-top: 1px solid var(--controller-border);
    box-shadow: 0 -4px 15px var(--controller-shadow);
    z-index: 10;
    box-sizing: border-box;
    gap: 8px;
  }

  .touch-btn {
    height: 44px;
    border-radius: 8px;
    font-size: 16px;
  }

  .touch-btn span {
    font-size: 10px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .btn,
  .start-button,
  .touch-btn {
    transition: none;
  }
}