body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", Arial, sans-serif;
  background:
    radial-gradient(circle at top, rgba(95, 76, 255, 0.18), transparent 24%),
    linear-gradient(180deg, #090d23 0%, #050816 100%);
  color: #eef1ff;
}

.hero {
  padding: 56px 24px 20px;
}

.hero-copy,
.game-section,
.feature-section,
.steps-section {
  max-width: 1100px;
  margin: 0 auto;
}

.eyebrow {
  margin: 0 0 10px;
  color: #7f6bff;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-size: 12px;
}

h1 {
  margin: 0;
  font-size: clamp(38px, 7vw, 68px);
  line-height: 0.98;
}

.hero-text {
  max-width: 700px;
  margin: 18px 0 0;
  color: #b7bfd9;
  font-size: 18px;
  line-height: 1.7;
}

main {
  padding: 0 24px 64px;
}

#game {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 28px;
  padding: 24px;
  border: 1px solid rgba(126, 104, 255, 0.2);
  border-radius: 28px;
  background: rgba(14, 20, 49, 0.72);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.28);
}

#board {
  display: grid;
  grid-template-columns: repeat(8, 88px);
  border: 6px solid rgba(255, 255, 255, 0.12);
  border-radius: 18px;
  overflow: hidden;
  box-shadow: 0 18px 40px rgba(0, 0, 0, 0.25);
}

.square {
  position: relative;
  width: 88px;
  height: 88px;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  overflow: hidden;
}

.white {
  background: #edd7ab;
}

.black {
  background: #bd9169;
}

.selected {
  outline: 3px solid #ffe85d;
  outline-offset: -3px;
}

.move {
  background: #6bcf63 !important;
}

.quantum {
  box-shadow: inset 0 0 0 3px rgba(139, 92, 246, 0.85);
}

.entangled::after {
  content: "";
  position: absolute;
  inset: 9px;
  border: 2px dashed rgba(56, 218, 255, 0.85);
  border-radius: 16px;
  pointer-events: none;
}

.coord {
  position: absolute;
  font-size: 11px;
  font-weight: 700;
  opacity: 0.45;
  color: rgba(8, 12, 28, 0.78);
  pointer-events: none;
}

.coord.file {
  right: 7px;
  bottom: 5px;
}

.coord.rank {
  left: 6px;
  top: 4px;
}

.piece,
.piece-glyph {
  position: absolute;
  width: 58px;
  height: 58px;
  user-select: none;
}

.piece {
  cursor: grab;
  transition: transform 0.2s ease-in-out, opacity 0.2s ease-in-out;
}

.piece-glyph {
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 54px;
  line-height: 1;
  color: #0a0a0a;
  text-shadow: 0 1px 0 rgba(255, 255, 255, 0.18);
}

.piece:hover,
.piece-glyph:hover {
  transform: scale(1.08);
}

.quantum .piece,
.quantum .piece-glyph {
  opacity: 0.84;
}

.piece-badge {
  position: absolute;
  top: 5px;
  right: 5px;
  z-index: 2;
  padding: 2px 6px;
  border-radius: 999px;
  background: rgba(8, 12, 28, 0.88);
  color: #ffffff;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

#panel {
  min-width: 270px;
  max-width: 320px;
  padding: 22px;
  border-radius: 22px;
  background: rgba(255, 255, 255, 0.06);
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.16);
}

#panel h3 {
  margin-top: 0;
  font-size: 24px;
}

#panel button {
  width: 100%;
  margin: 8px 0;
  padding: 14px 16px;
  border: 1px solid rgba(126, 104, 255, 0.3);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.08);
  color: #eef1ff;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
}

#panel button.active {
  background: linear-gradient(135deg, #7c3aed, #4f46e5);
  border-color: transparent;
}

#status {
  color: #c7cee8;
  line-height: 1.6;
}

#legend {
  margin: 14px 0 0;
  padding-left: 18px;
  color: #afb7d4;
  line-height: 1.6;
  font-size: 14px;
}

.hub-stack {
  display: grid;
  gap: 12px;
  margin-top: 14px;
}

.hub-card {
  padding: 14px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(126, 104, 255, 0.18);
}

.hub-label {
  margin: 0 0 8px;
  color: #7f6bff;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-size: 12px;
}

.hub-copy {
  margin: 0;
  color: #eef1ff;
  line-height: 1.5;
}

.hub-copy-muted {
  margin-top: 6px;
  color: #aeb8d8;
  font-size: 14px;
}

.hub-controls {
  display: grid;
  gap: 8px;
}

.hub-controls input {
  width: 100%;
  padding: 12px 14px;
  border: 1px solid rgba(126, 104, 255, 0.24);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.06);
  color: #eef1ff;
  font: inherit;
}

.hub-controls input:focus {
  outline: none;
  border-color: #ffb21d;
  box-shadow: 0 0 0 3px rgba(255, 178, 29, 0.12);
}

.hub-list {
  display: grid;
  gap: 10px;
}

.hub-empty {
  padding: 10px 12px;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.04);
  color: #aeb8d8;
  font-size: 14px;
}

.hub-entry {
  display: grid;
  gap: 10px;
  padding: 12px;
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.hub-entry strong {
  color: #ffffff;
  font-size: 15px;
}

.hub-entry span {
  color: #bfc6de;
  font-size: 13px;
  line-height: 1.5;
}

.hub-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.hub-actions button {
  min-height: 38px;
  padding: 8px 12px;
  font-size: 13px;
  font-weight: 700;
}

.section-heading {
  margin: 68px 0 28px;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(28px, 4vw, 40px);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.feature-card {
  padding: 40px;
  border: 1px solid rgba(107, 90, 255, 0.35);
  border-radius: 22px;
  background: #0f1530;
}

.feature-card h3 {
  margin: 22px 0 18px;
  font-size: 28px;
}

.feature-card p {
  margin: 0 0 24px;
  color: #a8b0ca;
  font-size: 18px;
  line-height: 1.7;
}

.feature-icon {
  width: 74px;
  height: 74px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(123, 58, 237, 0.18);
  border: 1px solid rgba(123, 107, 255, 0.45);
  color: #cbbfff;
  font-size: 34px;
}

.learn-more {
  border: none;
  background: transparent;
  color: #ffb21d;
  font-size: 17px;
  font-weight: 700;
  cursor: pointer;
  padding: 0;
}

.learn-more::after {
  content: " \2192";
}

.step-list {
  display: grid;
  gap: 28px;
}

.step-item {
  display: flex;
  gap: 28px;
  align-items: flex-start;
}

.step-badge {
  width: 52px;
  height: 52px;
  flex: 0 0 52px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  background: linear-gradient(180deg, #7c3aed, #6d28d9);
  color: white;
  font-size: 26px;
  font-weight: 700;
}

.step-copy h3 {
  margin: 4px 0 10px;
  color: #ffb21d;
  font-size: 28px;
}

.step-copy p {
  margin: 0;
  color: #d6d9e7;
  font-size: 18px;
  line-height: 1.7;
}

.modal {
  position: fixed;
  inset: 0;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: rgba(2, 6, 20, 0.72);
  z-index: 40;
}

.modal.open {
  display: flex;
}

.modal-card {
  position: relative;
  max-width: 580px;
  width: min(100%, 580px);
  padding: 30px 28px;
  border: 1px solid rgba(107, 90, 255, 0.35);
  border-radius: 24px;
  background: #0f1530;
  box-shadow: 0 30px 70px rgba(0, 0, 0, 0.35);
}

.modal-card h3 {
  margin: 0 0 14px;
  font-size: 30px;
}

.modal-card p {
  color: #bfc6de;
  line-height: 1.7;
  font-size: 17px;
}

.modal-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 40px;
  height: 40px;
  border: none;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.08);
  color: #ffffff;
  font-size: 28px;
  cursor: pointer;
}

@media (max-width: 1100px) {
  .feature-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 900px) {
  #board {
    grid-template-columns: repeat(8, 56px);
  }

  .square {
    width: 56px;
    height: 56px;
  }

  .coord {
    font-size: 9px;
  }

  .piece,
  .piece-glyph {
    width: 42px;
    height: 42px;
  }

  .piece-glyph {
    font-size: 40px;
  }
}

@media (max-width: 700px) {
  .hero {
    padding-top: 40px;
  }

  main {
    padding: 0 14px 48px;
  }

  #game {
    padding: 16px;
  }

  #board {
    grid-template-columns: repeat(8, 42px);
  }

  .square {
    width: 42px;
    height: 42px;
  }

  .coord {
    font-size: 7px;
  }

  .piece,
  .piece-glyph {
    width: 31px;
    height: 31px;
  }

  .piece-glyph {
    font-size: 30px;
  }

  .piece-badge {
    top: 2px;
    right: 2px;
    padding: 1px 4px;
    font-size: 8px;
  }

  .feature-card {
    padding: 28px 22px;
  }

  .feature-card h3,
  .step-copy h3 {
    font-size: 20px;
  }

  .feature-card p,
  .step-copy p {
    font-size: 16px;
  }

  .step-item {
    gap: 18px;
  }

  .step-badge {
    width: 44px;
    height: 44px;
    flex-basis: 44px;
    font-size: 22px;
  }
}

body.play-app-page {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at top left, rgba(122, 92, 255, 0.12), transparent 22%),
    linear-gradient(180deg, #26231e 0%, #1f1d19 100%);
  color: #eef1ff;
  overflow-x: hidden;
}

.play-layout {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 210px minmax(0, 1fr);
}

.play-sidebar {
  background: rgba(0, 0, 0, 0.18);
  border-right: 1px solid rgba(255, 255, 255, 0.06);
  padding: 22px 18px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.sidebar-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: #fff;
  text-decoration: none;
}

.sidebar-brand .brand-mark {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  background: url('assets/branding/quantum-logo.png') center/cover no-repeat;
  box-shadow: 0 0 18px rgba(245, 178, 29, 0.28);
  flex-shrink: 0;
}

.sidebar-brand strong {
  font-size: 18px;
  line-height: 1.1;
}

.sidebar-brand span {
  display: block;
  color: #aeb6cf;
  font-size: 12px;
  margin-top: 2px;
}

.sidebar-nav {
  display: grid;
  gap: 10px;
}

.sidebar-link {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border-radius: 14px;
  color: #d8deee;
  text-decoration: none;
  font-weight: 700;
  transition: background 0.25s ease, color 0.25s ease, transform 0.25s ease;
}

.sidebar-link:hover,
.sidebar-link.is-active {
  background: rgba(124, 255, 120, 0.12);
  color: #ffffff;
  transform: translateX(2px);
}

.sidebar-link i {
  width: 18px;
  text-align: center;
  color: #ffb21d;
}

.sidebar-footer {
  margin-top: auto;
  display: grid;
  gap: 12px;
}

.sidebar-search {
  display: flex;
  align-items: center;
  gap: 10px;
  color: #aeb6cf;
  padding: 10px 12px;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.04);
}

.sidebar-cta {
  width: 100%;
  padding: 13px 14px;
  border: none;
  border-radius: 12px;
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}

.sidebar-cta.primary {
  background: linear-gradient(180deg, #7ccf55, #5ea237);
  color: #10210a;
}

.sidebar-cta.secondary {
  background: rgba(255, 255, 255, 0.08);
  color: #eef1ff;
}

.play-main {
  padding: 18px 20px;
}

.board-stage {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 360px;
  gap: 10px 26px;
  align-items: start;
}

.player-strip {
  display: flex;
  align-items: center;
  gap: 12px;
  color: #eef1ff;
}

.player-avatar {
  width: 42px;
  height: 42px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.12);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.player-avatar.is-player {
  background: linear-gradient(180deg, rgba(255,255,255,0.24), rgba(255,255,255,0.1));
}

.player-meta strong {
  display: block;
  font-size: 15px;
}

.player-meta span {
  color: #bfc6de;
  font-size: 13px;
}

body.play-app-page #game {
  display: contents;
}

.board-stage .player-strip {
  grid-column: 1 / 2;
}

body.play-app-page #board {
  grid-column: 1 / 2;
  grid-template-columns: repeat(8, minmax(44px, 86px));
  width: min(100%, 688px);
  border: 6px solid rgba(255, 255, 255, 0.08);
  border-radius: 0;
  box-shadow: 0 22px 40px rgba(0, 0, 0, 0.24);
}

body.play-app-page .square {
  width: 100%;
  height: auto;
  aspect-ratio: 1 / 1;
}

body.play-app-page .white {
  background: #ebe9c7;
}

body.play-app-page .black {
  background: #779952;
}

body.play-app-page .coord {
  color: rgba(20, 20, 20, 0.45);
}

.play-side-panel {
  grid-column: 2 / 3;
  grid-row: 1 / span 3;
  border-radius: 18px;
  background: rgba(0, 0, 0, 0.16);
  border: 1px solid rgba(255, 255, 255, 0.06);
  overflow: hidden;
}

.play-panel-header {
  padding: 18px 22px;
  background: rgba(0, 0, 0, 0.2);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.play-panel-header h2 {
  margin: 0;
  font-size: 30px;
  line-height: 1.1;
}

.play-panel-header p {
  margin: 8px 0 0;
  color: #bfc6de;
}

body.play-app-page #panel {
  min-width: 0;
  max-width: none;
  padding: 18px;
  border-radius: 0;
  background: transparent;
  box-shadow: none;
}

.action-stack {
  display: grid;
  gap: 14px;
  margin-bottom: 18px;
}

.action-card {
  display: flex;
  gap: 14px;
  align-items: flex-start;
  padding: 18px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.action-card i {
  width: 46px;
  height: 46px;
  border-radius: 12px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  color: #ffcf53;
  background: rgba(255, 194, 46, 0.12);
  flex-shrink: 0;
}

.action-copy strong {
  display: block;
  font-size: 17px;
  color: #fff;
  margin-bottom: 4px;
}

.action-copy span {
  color: #bfc6de;
  line-height: 1.5;
  font-size: 14px;
}

.premium-status-card {
  margin-bottom: 18px;
  padding: 16px 18px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.premium-benefits-list {
  margin: 12px 0 0;
  padding-left: 18px;
  color: #d9def1;
  line-height: 1.6;
  font-size: 14px;
}

.premium-benefits-list li + li {
  margin-top: 6px;
}

.ad-rail {
  display: grid;
  gap: 14px;
  margin-bottom: 18px;
}

.ad-slot {
  display: grid;
  gap: 10px;
  padding: 16px 18px;
  border-radius: 16px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(255, 255, 255, 0.03));
  border: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.16);
}

.adsense-shell {
  display: block;
  min-height: 130px;
}

.adsense-shell .adsbygoogle {
  min-height: 90px;
}

.ad-slot.wide {
  min-height: 138px;
}

.ad-kicker {
  color: #ffcf53;
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.ad-title {
  color: #ffffff;
  font-size: 18px;
  line-height: 1.3;
}

.ad-copy {
  color: #c7cee8;
  font-size: 14px;
  line-height: 1.6;
}

.ad-cta {
  color: #8fd36d;
  font-weight: 800;
  font-size: 14px;
}

.bottom-ad-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  margin-top: 14px;
}

.full-span {
  grid-column: 1 / -1;
}

.ad-free-banner {
  margin-top: 10px;
  padding: 14px 16px;
  border-radius: 14px;
  background: rgba(124, 255, 120, 0.1);
  border: 1px solid rgba(124, 255, 120, 0.18);
  color: #a8ef88;
  font-weight: 700;
}

.is-hidden {
  display: none !important;
}

body.play-app-page #panel button {
  margin: 0;
}

body.play-app-page #panel button,
body.play-app-page .hub-controls button {
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

body.play-app-page #panel button.active {
  background: linear-gradient(135deg, #7c3aed, #4f46e5);
}

body.play-app-page #legend,
body.play-app-page #move-list,
body.play-app-page .hub-stack,
body.play-app-page .panel-actions,
body.play-app-page .substatus,
body.play-app-page .section-label {
  margin-top: 14px;
}

@media (max-width: 1180px) {
  .board-stage {
    grid-template-columns: 1fr;
  }

  .play-side-panel,
  body.play-app-page #board,
  .board-stage .player-strip {
    grid-column: 1 / 2;
  }

  .play-side-panel {
    grid-row: auto;
  }
}

@media (max-width: 860px) {
  .play-layout {
    grid-template-columns: 1fr;
  }

  .play-sidebar {
    border-right: none;
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  }

  .sidebar-nav {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 620px) {
  .play-main {
    padding: 14px 12px 24px;
  }

  .sidebar-nav {
    grid-template-columns: 1fr;
  }

  body.play-app-page #board {
    width: 100%;
  }

  .play-panel-header h2 {
    font-size: 24px;
  }

  .bottom-ad-row {
    grid-template-columns: 1fr;
  }
}