:root {
  --bg-deep: #060913;
  --bg-surface: rgba(15, 23, 42, 0.68);
  --bg-surface-elevated: rgba(30, 41, 59, 0.72);
  --border-glass: rgba(148, 163, 184, 0.16);
  --border-highlight: rgba(255, 255, 255, 0.24);

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  /* Player X: Electric Cyan */
  --x-primary: #22d3ee;
  --x-glow: rgba(34, 211, 238, 0.55);
  --x-soft: rgba(34, 211, 238, 0.14);

  /* Player O: Neon Coral / Rose */
  --o-primary: #fb7185;
  --o-glow: rgba(251, 113, 133, 0.55);
  --o-soft: rgba(251, 113, 133, 0.14);

  /* Tactical / Hint: Amber Gold */
  --accent-gold: #fbbf24;
  --accent-gold-glow: rgba(251, 191, 36, 0.55);
  --accent-indigo: #818cf8;

  /* 3D Camera State Variables */
  --cam-pitch: -24deg;
  --cam-yaw: -36deg;
  --cam-zoom: 1;

  --radius-lg: 16px;
  --radius-md: 12px;
  --radius-sm: 8px;
}

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

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-deep);
  background-image:
    radial-gradient(circle at 50% 45%, rgba(30, 58, 138, 0.22) 0%, transparent 65%),
    linear-gradient(180deg, #050811 0%, #090d1c 100%);
  color: var(--text-primary);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  -webkit-font-smoothing: antialiased;
}

#fx-canvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 1;
}

.ambient-glow {
  position: fixed;
  width: 480px;
  height: 480px;
  border-radius: 50%;
  filter: blur(130px);
  opacity: 0.18;
  pointer-events: none;
  z-index: 0;
  transition: opacity 0.6s ease;
}

.glow-cyan {
  top: -120px;
  left: 12%;
  background: var(--x-primary);
}

.glow-rose {
  bottom: -140px;
  right: 12%;
  background: var(--o-primary);
}

/* GLASS PANEL UTILITY */
.glass-panel {
  background: var(--bg-surface);
  backdrop-filter: blur(20px) saturate(160%);
  -webkit-backdrop-filter: blur(20px) saturate(160%);
  border: 1px solid var(--border-glass);
  box-shadow: 0 16px 40px -12px rgba(0, 0, 0, 0.65), inset 0 1px 0 rgba(255, 255, 255, 0.08);
}

.glass-pill {
  background: rgba(15, 23, 42, 0.78);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-glass);
  border-radius: 999px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.45);
}

/* APP SHELL */
.app-shell {
  position: relative;
  z-index: 2;
  display: flex;
  flex-direction: column;
  width: 100vw;
  height: 100vh;
  padding: 12px 16px;
  gap: 12px;
}

/* TOPBAR */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 20px;
  border-radius: var(--radius-lg);
  min-height: 68px;
  flex-shrink: 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-logo {
  width: 40px;
  height: 40px;
  border-radius: 11px;
  background: linear-gradient(135deg, rgba(34, 211, 238, 0.2), rgba(251, 113, 133, 0.2));
  border: 1px solid rgba(255, 255, 255, 0.18);
  display: grid;
  place-items: center;
  box-shadow: 0 0 20px rgba(34, 211, 238, 0.2);
}

.cube-icon {
  width: 18px;
  height: 18px;
  border: 2px solid var(--x-primary);
  border-radius: 4px;
  position: relative;
  transform: rotate(15deg);
  box-shadow: 4px 4px 0 -1px var(--o-primary);
}

.brand-text h1 {
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  display: flex;
  align-items: center;
  gap: 6px;
}

.accent-badge {
  font-size: 0.72rem;
  padding: 2px 7px;
  border-radius: 6px;
  background: linear-gradient(135deg, var(--x-primary), var(--accent-indigo));
  color: #041019;
  font-weight: 800;
}

.subtitle {
  font-size: 0.75rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* SCOREBOARD */
.scoreboard {
  display: flex;
  align-items: center;
  gap: 14px;
}

.score-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 7px 14px;
  border-radius: var(--radius-md);
  background: rgba(15, 23, 42, 0.55);
  border: 1px solid rgba(148, 163, 184, 0.14);
  min-width: 175px;
  transition: all 0.3s cubic-bezier(0.22, 1, 0.36, 1);
}

.score-card.player-x.active-turn {
  background: var(--x-soft);
  border-color: var(--x-primary);
  box-shadow: 0 0 22px rgba(34, 211, 238, 0.25);
  transform: translateY(-1px);
}

.score-card.player-o.active-turn {
  background: var(--o-soft);
  border-color: var(--o-primary);
  box-shadow: 0 0 22px rgba(251, 113, 133, 0.25);
  transform: translateY(-1px);
}

.player-indicator {
  display: flex;
  align-items: center;
  gap: 10px;
}

.player-indicator.right {
  text-align: right;
}

.symbol-x, .symbol-o {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  font-weight: 800;
  font-size: 1rem;
}

.symbol-x {
  background: rgba(34, 211, 238, 0.18);
  color: var(--x-primary);
  border: 1px solid rgba(34, 211, 238, 0.4);
  text-shadow: 0 0 10px var(--x-glow);
}

.symbol-o {
  background: rgba(251, 113, 133, 0.18);
  color: var(--o-primary);
  border: 1px solid rgba(251, 113, 133, 0.4);
  text-shadow: 0 0 10px var(--o-glow);
}

.player-meta {
  display: flex;
  flex-direction: column;
}

.player-name {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--text-primary);
}

.turn-tag {
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text-secondary);
}

.active-turn.player-x .turn-tag {
  color: var(--x-primary);
}

.active-turn.player-o .turn-tag {
  color: var(--o-primary);
}

.score-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 1.35rem;
  font-weight: 700;
}

.score-divider {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0 4px;
}

.draws-label {
  font-size: 0.62rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.draws-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.icon-btn {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  border: 1px solid var(--border-glass);
  background: rgba(30, 41, 59, 0.55);
  color: var(--text-primary);
  display: grid;
  place-items: center;
  cursor: pointer;
  transition: all 0.2s ease;
}

.icon-btn:hover {
  background: rgba(51, 65, 85, 0.8);
  border-color: var(--border-highlight);
  transform: translateY(-1px);
}

.hidden {
  display: none !important;
}

/* MAIN WORKSPACE GRID */
.workspace {
  flex: 1;
  display: grid;
  grid-template-columns: 290px 1fr 270px;
  gap: 12px;
  min-height: 0;
}

/* SIDE PANELS */
.side-panel {
  border-radius: var(--radius-lg);
  padding: 14px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  overflow-y: auto;
  min-height: 0;
}

.side-panel::-webkit-scrollbar {
  width: 5px;
}
.side-panel::-webkit-scrollbar-thumb {
  background: rgba(148, 163, 184, 0.2);
  border-radius: 99px;
}

.panel-section {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding-bottom: 12px;
  border-bottom: 1px solid rgba(148, 163, 184, 0.1);
}

.panel-section:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

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

.section-title {
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
}

.control-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-secondary);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.key-hint {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.65rem;
  color: var(--text-muted);
}

.sub-control {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

/* SEGMENTED CONTROLS */
.segmented-control {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: 1fr;
  background: rgba(9, 13, 26, 0.65);
  padding: 3px;
  border-radius: 10px;
  border: 1px solid rgba(148, 163, 184, 0.12);
  gap: 3px;
}

.seg-btn {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.76rem;
  font-weight: 600;
  padding: 7px 8px;
  border-radius: 7px;
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.segmented-control.compact .seg-btn {
  font-size: 0.71rem;
  padding: 5px 6px;
}

.seg-btn:hover {
  color: var(--text-primary);
}

.seg-btn.active {
  background: rgba(56, 189, 248, 0.16);
  color: var(--x-primary);
  box-shadow: inset 0 0 0 1px rgba(34, 211, 238, 0.35);
}

/* SLIDER & PILLS */
.slider-group {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.slider-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.75rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.mono-badge {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  padding: 2px 6px;
  border-radius: 5px;
  background: rgba(148, 163, 184, 0.12);
  color: var(--text-primary);
}

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 5px;
  border-radius: 99px;
  background: rgba(148, 163, 184, 0.2);
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--x-primary);
  cursor: pointer;
  box-shadow: 0 0 10px var(--x-glow);
  border: 2px solid #fff;
}

.layer-filter-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.layer-pills {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 4px;
}

.layer-pill {
  padding: 6px 4px;
  font-size: 0.7rem;
  font-weight: 600;
  font-family: inherit;
  border-radius: 7px;
  background: rgba(15, 23, 42, 0.6);
  border: 1px solid rgba(148, 163, 184, 0.15);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.18s ease;
}

.layer-pill:hover {
  color: var(--text-primary);
  border-color: rgba(148, 163, 184, 0.35);
}

.layer-pill.active {
  background: rgba(129, 140, 248, 0.2);
  color: #c7d2fe;
  border-color: var(--accent-indigo);
}

/* TOGGLE SWITCHES */
.toggle-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.toggle-label {
  display: flex;
  flex-direction: column;
  cursor: pointer;
}

.toggle-label span {
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--text-primary);
}

.toggle-label small {
  font-size: 0.66rem;
  color: var(--text-muted);
}

.switch-input {
  appearance: none;
  -webkit-appearance: none;
  width: 36px;
  height: 20px;
  background: rgba(148, 163, 184, 0.22);
  border-radius: 99px;
  position: relative;
  cursor: pointer;
  transition: background 0.25s ease;
  flex-shrink: 0;
}

.switch-input::after {
  content: "";
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  background: #fff;
  border-radius: 50%;
  transition: transform 0.25s cubic-bezier(0.22, 1, 0.36, 1);
}

.switch-input:checked {
  background: var(--x-primary);
}

.switch-input:checked::after {
  transform: translateX(16px);
}

/* BUTTONS */
.text-btn {
  background: none;
  border: none;
  color: var(--x-primary);
  font-size: 0.72rem;
  font-weight: 600;
  cursor: pointer;
  opacity: 0.85;
}
.text-btn:hover {
  opacity: 1;
  text-decoration: underline;
}

.action-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  padding: 9px 12px;
  border-radius: 10px;
  font-family: inherit;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.2s cubic-bezier(0.22, 1, 0.36, 1);
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none !important;
}

.btn-secondary {
  background: rgba(30, 41, 59, 0.75);
  border-color: rgba(148, 163, 184, 0.2);
  color: var(--text-primary);
}
.btn-secondary:hover:not(:disabled) {
  background: rgba(51, 65, 85, 0.85);
  border-color: rgba(148, 163, 184, 0.4);
  transform: translateY(-1px);
}

.btn-accent {
  background: rgba(251, 191, 36, 0.14);
  border-color: rgba(251, 191, 36, 0.4);
  color: var(--accent-gold);
}
.btn-accent:hover:not(:disabled) {
  background: rgba(251, 191, 36, 0.24);
  box-shadow: 0 0 18px rgba(251, 191, 36, 0.25);
  transform: translateY(-1px);
}

.btn-primary {
  background: linear-gradient(135deg, #06b6d4, #3b82f6);
  color: #fff;
  border-color: rgba(255, 255, 255, 0.2);
  box-shadow: 0 6px 20px rgba(6, 182, 212, 0.3);
}
.btn-primary:hover {
  filter: brightness(1.1);
  transform: translateY(-1px);
  box-shadow: 0 8px 25px rgba(6, 182, 212, 0.45);
}

.full-width {
  width: 100%;
}

/* MOVE HISTORY */
.history-section {
  flex: 1;
  min-height: 90px;
  overflow: hidden;
}

.move-list {
  flex: 1;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding-right: 4px;
}

.move-list::-webkit-scrollbar {
  width: 4px;
}
.move-list::-webkit-scrollbar-thumb {
  background: rgba(148, 163, 184, 0.2);
  border-radius: 99px;
}

.empty-history {
  font-size: 0.74rem;
  color: var(--text-muted);
  line-height: 1.4;
  padding: 8px 0;
}

.move-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 5px 8px;
  border-radius: 7px;
  background: rgba(15, 23, 42, 0.55);
  border: 1px solid rgba(148, 163, 184, 0.1);
  font-size: 0.73rem;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease;
}

.move-item:hover {
  background: rgba(30, 41, 59, 0.85);
  border-color: rgba(148, 163, 184, 0.3);
}

.move-badge {
  font-weight: 700;
  font-family: 'JetBrains Mono', monospace;
}

.move-badge.x { color: var(--x-primary); }
.move-badge.o { color: var(--o-primary); }

.move-coord {
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-secondary);
  font-size: 0.7rem;
}

/* =========================================
   CENTER 3D VIEWPORT & SPATIAL SCENE
   ========================================= */
.viewport-stage {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(148, 163, 184, 0.12);
  background: radial-gradient(circle at 50% 50%, rgba(15, 23, 42, 0.4) 0%, rgba(6, 9, 19, 0.75) 100%);
  overflow: hidden;
  cursor: grab;
}

.viewport-stage.dragging {
  cursor: grabbing;
}

.hud-top, .hud-bottom {
  position: relative;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 18px;
  pointer-events: none;
}

.hud-bottom {
  justify-content: center;
}

.status-banner, .coord-readout, .camera-dock {
  pointer-events: auto;
}

.status-banner {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 16px;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-primary);
  transition: all 0.3s ease;
}

.status-banner.win-x {
  border-color: var(--x-primary);
  box-shadow: 0 0 25px rgba(34, 211, 238, 0.35);
}

.status-banner.win-o {
  border-color: var(--o-primary);
  box-shadow: 0 0 25px rgba(251, 113, 133, 0.35);
}

.status-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--x-primary);
  box-shadow: 0 0 10px var(--x-primary);
  transition: background 0.3s ease, box-shadow 0.3s ease;
}

.coord-readout {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.74rem;
}

.coord-label {
  color: var(--text-muted);
  font-weight: 700;
}

.coord-value {
  color: var(--accent-gold);
  font-weight: 700;
  min-width: 82px;
  text-align: right;
}

/* CAMERA DOCK */
.camera-dock {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 5px 10px;
}

.cam-btn {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.74rem;
  font-weight: 600;
  padding: 5px 11px;
  border-radius: 99px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.cam-btn:hover {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.06);
}

.cam-btn.active {
  background: rgba(34, 211, 238, 0.18);
  color: var(--x-primary);
}

.dock-sep {
  width: 1px;
  height: 16px;
  background: rgba(148, 163, 184, 0.2);
  margin: 0 6px;
}

.drag-hint {
  font-size: 0.7rem;
  color: var(--text-muted);
  padding-right: 6px;
}

/* 3D STAGE & PRESERVE-3D HIERARCHY */
.scene-container {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  perspective: 1150px;
  overflow: hidden;
}

.scene-3d {
  position: relative;
  width: 0;
  height: 0;
  transform-style: preserve-3d;
  transform: scale(var(--cam-zoom)) rotateX(var(--cam-pitch)) rotateY(var(--cam-yaw));
  transition: transform 0.06s linear;
}

.scene-3d.smooth-cam {
  transition: transform 0.55s cubic-bezier(0.22, 1, 0.36, 1);
}

.pillars-group, .layers-group, .beams-group {
  position: absolute;
  top: 0;
  left: 0;
  transform-style: preserve-3d;
}

/* VERTICAL STRUCTURAL PILLARS */
.pillar-line {
  position: absolute;
  width: 2px;
  left: -1px;
  background: linear-gradient(
    180deg,
    rgba(56, 189, 248, 0.04) 0%,
    rgba(148, 163, 184, 0.16) 20%,
    rgba(148, 163, 184, 0.16) 80%,
    rgba(251, 113, 133, 0.04) 100%
  );
  transform-style: preserve-3d;
  pointer-events: none;
  transition: height 0.25s ease, top 0.25s ease;
}

/* LAYER PLATFORM BOARD */
.layer-plane {
  position: absolute;
  width: 288px;
  height: 288px;
  left: -144px;
  top: -144px;
  border-radius: 20px;
  background: rgba(15, 23, 42, 0.26);
  border: 1px solid rgba(148, 163, 184, 0.22);
  box-shadow:
    0 0 30px rgba(0, 0, 0, 0.35),
    inset 0 0 24px rgba(56, 189, 248, 0.04);
  transform-style: preserve-3d;
  pointer-events: none;
  transition: transform 0.3s cubic-bezier(0.22, 1, 0.36, 1), opacity 0.3s ease, border-color 0.3s ease;
}

.layer-plane.dimmed {
  opacity: 0.14;
}

.layer-plane-tag {
  position: absolute;
  top: -24px;
  left: 12px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: rgba(148, 163, 184, 0.65);
  text-transform: uppercase;
  pointer-events: none;
}

/* INDIVIDUAL 3D CELL NODE */
.cell-3d {
  position: absolute;
  width: 0;
  height: 0;
  transform-style: preserve-3d;
  transition: transform 0.3s cubic-bezier(0.22, 1, 0.36, 1), opacity 0.3s ease;
}

.cell-3d.dimmed {
  opacity: 0.14;
  pointer-events: none;
}

/* CLICKABLE HORIZONTAL GLASS TILE AT (x, y, z) */
.cell-pad {
  position: absolute;
  width: 80px;
  height: 80px;
  left: -40px;
  top: -40px;
  border-radius: 14px;
  background: rgba(30, 41, 59, 0.48);
  border: 1.5px solid rgba(148, 163, 184, 0.24);
  transform: rotateX(90deg);
  transform-style: preserve-3d;
  cursor: pointer;
  display: grid;
  place-items: center;
  transition:
    background 0.2s ease,
    border-color 0.2s ease,
    box-shadow 0.2s ease,
    transform 0.2s ease;
}

/* Center Nexus Tile Special Accent */
.cell-3d.is-nexus .cell-pad {
  border-color: rgba(251, 191, 36, 0.38);
  background: rgba(251, 191, 36, 0.07);
}

.pad-coord {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.58rem;
  font-weight: 600;
  color: rgba(148, 163, 184, 0.35);
  pointer-events: none;
  transition: color 0.2s ease;
}

.cell-3d:hover .cell-pad,
.cell-3d.synced-hover .cell-pad {
  background: rgba(56, 189, 248, 0.22);
  border-color: var(--x-primary);
  box-shadow: 0 0 22px rgba(34, 211, 238, 0.45), inset 0 0 12px rgba(34, 211, 238, 0.25);
}

body.turn-o .cell-3d:hover .cell-pad,
body.turn-o .cell-3d.synced-hover .cell-pad {
  background: rgba(251, 113, 133, 0.22);
  border-color: var(--o-primary);
  box-shadow: 0 0 22px rgba(251, 113, 133, 0.45), inset 0 0 12px rgba(251, 113, 133, 0.25);
}

.cell-3d:hover .pad-coord,
.cell-3d.synced-hover .pad-coord {
  color: rgba(255, 255, 255, 0.85);
}

/* X-RAY RADAR INTERSECTING LINE HIGHLIGHT */
.cell-3d.radar-line .cell-pad {
  border-color: rgba(129, 140, 248, 0.55);
  background: rgba(99, 102, 241, 0.16);
}

.cell-3d.radar-threat .cell-pad {
  border-color: var(--accent-gold);
  background: rgba(251, 191, 36, 0.22);
  box-shadow: 0 0 20px rgba(251, 191, 36, 0.45);
}

/* AI HINT HIGHLIGHT */
.cell-3d.hint-target .cell-pad {
  border-color: var(--accent-gold);
  background: rgba(251, 191, 36, 0.28);
  box-shadow: 0 0 28px var(--accent-gold-glow), inset 0 0 15px var(--accent-gold-glow);
  animation: pulseHintPad 1.2s infinite alternate;
}

@keyframes pulseHintPad {
  0% { transform: rotateX(90deg) scale(0.96); }
  100% { transform: rotateX(90deg) scale(1.06); }
}

/* WINNING CELL HIGHLIGHT */
.cell-3d.win-cell .cell-pad {
  border-width: 2px;
  border-color: #fff;
  box-shadow: 0 0 32px rgba(255, 255, 255, 0.75);
}

/* =========================================
   3D VOLUMETRIC HOLOGRAPHIC PIECES (X & O)
   ========================================= */
.piece-anchor {
  position: absolute;
  top: 0;
  left: 0;
  width: 0;
  height: 0;
  transform-style: preserve-3d;
  pointer-events: none;
}

/* Spherical Billboard faces camera at ANY 3D rotation angle */
.piece-billboard {
  position: absolute;
  width: 56px;
  height: 56px;
  left: -28px;
  top: -28px;
  display: grid;
  place-items: center;
  transform-style: preserve-3d;
  transform: rotateY(calc(-1 * var(--cam-yaw))) rotateX(calc(-1 * var(--cam-pitch)));
  animation: popInPiece 0.34s cubic-bezier(0.34, 1.56, 0.64, 1) forwards;
}

@keyframes popInPiece {
  0% {
    opacity: 0;
    transform: rotateY(calc(-1 * var(--cam-yaw))) rotateX(calc(-1 * var(--cam-pitch))) scale(0.2);
  }
  100% {
    opacity: 1;
    transform: rotateY(calc(-1 * var(--cam-yaw))) rotateX(calc(-1 * var(--cam-pitch))) scale(1);
  }
}

/* True 3D Orbital Aura Ring lying on the horizontal pad */
.piece-base-halo {
  position: absolute;
  width: 58px;
  height: 58px;
  left: -29px;
  top: -29px;
  border-radius: 50%;
  transform: rotateX(90deg);
  pointer-events: none;
}

.piece-base-halo.x {
  border: 2px dashed rgba(34, 211, 238, 0.45);
  background: radial-gradient(circle, rgba(34, 211, 238, 0.25) 0%, transparent 70%);
  box-shadow: 0 0 18px rgba(34, 211, 238, 0.35);
}

.piece-base-halo.o {
  border: 2px dashed rgba(251, 113, 133, 0.45);
  background: radial-gradient(circle, rgba(251, 113, 133, 0.25) 0%, transparent 70%);
  box-shadow: 0 0 18px rgba(251, 113, 133, 0.35);
}

/* X HOLOGRAM SCULPTURE */
.holo-x {
  position: relative;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
}

.holo-x::before,
.holo-x::after {
  content: "";
  position: absolute;
  width: 42px;
  height: 9px;
  border-radius: 99px;
  background: linear-gradient(90deg, #67e8f9, #06b6d4, #67e8f9);
  box-shadow:
    0 0 14px var(--x-primary),
    0 0 28px rgba(34, 211, 238, 0.55),
    inset 0 1px 2px rgba(255, 255, 255, 0.8);
}

.holo-x::before { transform: rotate(45deg); }
.holo-x::after  { transform: rotate(-45deg); }

/* O HOLOGRAM SCULPTURE */
.holo-o {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  border: 8px solid var(--o-primary);
  background: radial-gradient(circle, rgba(251, 113, 133, 0.25) 0%, transparent 68%);
  box-shadow:
    0 0 14px var(--o-primary),
    0 0 28px rgba(251, 113, 133, 0.55),
    inset 0 0 10px rgba(255, 255, 255, 0.65);
}

/* Ghost Hover Preview Piece */
.ghost-preview {
  opacity: 0.42;
  filter: saturate(0.85);
}

/* Last-placed move indicator ring */
.cell-3d.last-move .cell-pad::after {
  content: "";
  position: absolute;
  inset: 4px;
  border-radius: 10px;
  border: 1.5px solid rgba(255, 255, 255, 0.5);
  pointer-events: none;
}

/* =========================================
   3D VOLUMETRIC WINNING LASER BEAM
   ========================================= */
.laser-beam-3d {
  position: absolute;
  top: 0;
  left: 0;
  height: 0;
  transform-style: preserve-3d;
  pointer-events: none;
}

.laser-plane {
  position: absolute;
  top: -6px;
  left: 0;
  width: 100%;
  height: 12px;
  border-radius: 99px;
  background: linear-gradient(90deg, rgba(255,255,255,0.9), var(--beam-color, #22d3ee), rgba(255,255,255,0.9));
  box-shadow:
    0 0 18px var(--beam-color, #22d3ee),
    0 0 36px var(--beam-color, #22d3ee);
  animation: pulseLaser 0.9s ease-in-out infinite alternate;
}

.laser-plane.cross {
  transform: rotateX(90deg);
}

@keyframes pulseLaser {
  0% { opacity: 0.82; filter: brightness(1); }
  100% { opacity: 1; filter: brightness(1.35); }
}

/* =========================================
   RIGHT PANEL: 2D SYNCHRONIZED LAYER SLICES
   ========================================= */
.slice-subtitle {
  font-size: 0.68rem;
  color: var(--x-primary);
  font-weight: 600;
}

.helper-caption {
  font-size: 0.71rem;
  color: var(--text-muted);
  line-height: 1.35;
}

.slices-container {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 2px;
}

.slice-card {
  padding: 8px 10px;
  border-radius: 12px;
  background: rgba(9, 13, 26, 0.55);
  border: 1px solid rgba(148, 163, 184, 0.14);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  transition: border-color 0.2s ease, background 0.2s ease;
}

.slice-card.focused-layer {
  border-color: var(--accent-indigo);
  background: rgba(99, 102, 241, 0.1);
}

.slice-info {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.slice-title {
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--text-primary);
}

.slice-tag {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.64rem;
  color: var(--text-muted);
}

.slice-focus-btn {
  margin-top: 4px;
  align-self: flex-start;
  padding: 2px 7px;
  font-size: 0.63rem;
  font-weight: 600;
  border-radius: 5px;
  border: 1px solid rgba(148, 163, 184, 0.2);
  background: rgba(30, 41, 59, 0.6);
  color: var(--text-secondary);
  cursor: pointer;
}
.slice-focus-btn:hover {
  color: var(--text-primary);
  border-color: var(--x-primary);
}

.slice-grid {
  display: grid;
  grid-template-columns: repeat(3, 34px);
  grid-template-rows: repeat(3, 34px);
  gap: 4px;
}

.slice-cell {
  width: 34px;
  height: 34px;
  border-radius: 7px;
  background: rgba(30, 41, 59, 0.65);
  border: 1px solid rgba(148, 163, 184, 0.2);
  display: grid;
  place-items: center;
  font-size: 0.85rem;
  font-weight: 800;
  cursor: pointer;
  transition: all 0.16s ease;
}

.slice-cell.is-nexus {
  border-color: rgba(251, 191, 36, 0.4);
}

.slice-cell:hover,
.slice-cell.synced-hover {
  border-color: var(--x-primary);
  background: rgba(34, 211, 238, 0.2);
  transform: scale(1.06);
}

body.turn-o .slice-cell:hover,
body.turn-o .slice-cell.synced-hover {
  border-color: var(--o-primary);
  background: rgba(251, 113, 133, 0.2);
}

.slice-cell.x {
  color: var(--x-primary);
  background: rgba(34, 211, 238, 0.14);
  border-color: rgba(34, 211, 238, 0.45);
  text-shadow: 0 0 8px var(--x-glow);
}

.slice-cell.o {
  color: var(--o-primary);
  background: rgba(251, 113, 133, 0.14);
  border-color: rgba(251, 113, 133, 0.45);
  text-shadow: 0 0 8px var(--o-glow);
}

.slice-cell.radar-line {
  background: rgba(99, 102, 241, 0.22);
  border-color: rgba(129, 140, 248, 0.6);
}

.slice-cell.hint-target {
  border-color: var(--accent-gold);
  background: rgba(251, 191, 36, 0.28);
  box-shadow: 0 0 12px var(--accent-gold-glow);
}

.slice-cell.win-cell {
  border-color: #fff;
  box-shadow: 0 0 14px #fff;
}

/* TELEMETRY CARD */
.telemetry-card {
  background: rgba(9, 13, 26, 0.55);
  border: 1px solid rgba(148, 163, 184, 0.14);
  border-radius: 12px;
  padding: 10px 12px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.telemetry-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.74rem;
}

.tel-label {
  color: var(--text-secondary);
}

.tel-val {
  font-family: 'JetBrains Mono', monospace;
  font-weight: 600;
  font-size: 0.72rem;
  color: var(--text-primary);
}

.tel-val.highlight {
  color: var(--x-primary);
}

.tel-val.danger {
  color: var(--accent-gold);
}

.tactical-note {
  margin-top: 2px;
  padding-top: 8px;
  border-top: 1px solid rgba(148, 163, 184, 0.12);
  font-size: 0.71rem;
  line-height: 1.45;
  color: var(--text-secondary);
}

.tactical-note strong {
  color: var(--accent-gold);
}

/* =========================================
   MODAL (HOW TO PLAY & 49 WINNING LINES)
   ========================================= */
.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(3, 6, 14, 0.75);
  backdrop-filter: blur(8px);
  display: grid;
  place-items: center;
  padding: 20px;
}

.modal-card {
  width: 100%;
  max-width: 660px;
  border-radius: 20px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
  animation: modalEnter 0.25s cubic-bezier(0.22, 1, 0.36, 1);
}

@keyframes modalEnter {
  from { opacity: 0; transform: translateY(12px) scale(0.97); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.modal-header h2 {
  font-size: 1.2rem;
  font-weight: 800;
}

.modal-subtitle {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-top: 3px;
}

.rule-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.rule-box {
  padding: 14px;
  border-radius: 14px;
  background: rgba(9, 13, 26, 0.6);
  border: 1px solid rgba(148, 163, 184, 0.16);
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.rule-box.accent {
  border-color: rgba(251, 191, 36, 0.4);
  background: rgba(251, 191, 36, 0.06);
}

.rule-badge {
  align-self: flex-start;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  font-weight: 800;
  padding: 2px 8px;
  border-radius: 6px;
  background: rgba(34, 211, 238, 0.16);
  color: var(--x-primary);
}

.rule-box.accent .rule-badge {
  background: rgba(251, 191, 36, 0.2);
  color: var(--accent-gold);
}

.rule-box h3 {
  font-size: 0.88rem;
  font-weight: 700;
}

.rule-box p {
  font-size: 0.76rem;
  color: var(--text-secondary);
  line-height: 1.45;
}

.shortcuts-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 16px;
  padding: 12px 14px;
  border-radius: 12px;
  background: rgba(15, 23, 42, 0.7);
  border: 1px solid rgba(148, 163, 184, 0.12);
  font-size: 0.74rem;
  color: var(--text-secondary);
}

kbd {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.68rem;
  padding: 2px 6px;
  border-radius: 5px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: var(--text-primary);
  margin-right: 3px;
}

.modal-footer {
  display: flex;
  justify-content: flex-end;
}

/* RESPONSIVE BREAKPOINTS */
@media (max-width: 1120px) {
  .workspace {
    grid-template-columns: 250px 1fr 235px;
  }
  .score-card {
    min-width: 145px;
  }
}

@media (max-width: 900px) {
  html, body {
    overflow: auto;
  }
  .app-shell {
    height: auto;
    min-height: 100vh;
  }
  .workspace {
    grid-template-columns: 1fr;
    grid-template-rows: 480px auto auto;
  }
  .viewport-stage {
    order: 1;
    min-height: 480px;
  }
  .right-panel {
    order: 2;
  }
  .left-panel {
    order: 3;
  }
  .slices-container {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: space-around;
  }
}