:root {
  --bg: #07111f;
  --bg-2: #0d1c34;
  --panel: rgba(11, 22, 46, 0.88);
  --panel-2: rgba(16, 29, 60, 0.95);
  --line: rgba(120, 160, 255, 0.18);
  --text: #f8fbff;
  --muted: #9fb0d1;
  --blue: #4f46e5;
  --purple: #7c3aed;
  --green: #22c55e;
  --gold: #ffd54a;
  --danger: #ef4444;
  --shadow: 0 18px 40px rgba(0, 0, 0, 0.28);

  --c-i: #00c7ff;
  --c-o: #ffd600;
  --c-t: #b15cff;
  --c-s: #42e37b;
  --c-z: #ff6b6b;
  --c-j: #4c78ff;
  --c-l: #ff9f40;
}

* {
  box-sizing: border-box;
}

.site-header,
.game-shell,
.site-footer {
  width: min(1280px, calc(100% - 32px));
  margin-inline: auto;
}

@media (max-width: 640px) {
  .site-logo {
    height: 52px;
  }
}

.brand-mark {
  width: 56px;
  height: 56px;
  border-radius: 18px;
  display: grid;
  place-items: center;
  font-size: 1.4rem;
  font-weight: 900;
  text-decoration: none;
  color: white;
  background: linear-gradient(135deg, var(--blue), var(--purple));
  box-shadow: var(--shadow);
}

.brand h1 {
  margin: 0;
  font-size: clamp(1.8rem, 3vw, 2.6rem);
}

.brand p {
  margin: 4px 0 0;
  color: var(--muted);
}

.nav-link,
.primary-btn,
.secondary-btn {
  text-decoration: none;
  border-radius: 14px;
  padding: 12px 16px;
  font-weight: 800;
  color: white;
  cursor: pointer;
  transition:
    transform 0.18s ease,
    filter 0.18s ease;
}

.nav-link,
.secondary-btn {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.06);
}

.nav-link:hover,
.primary-btn:hover,
.secondary-btn:hover {
  transform: translateY(-2px);
  filter: brightness(1.06);
}

.secondary-btn:disabled {
  opacity: 0.55;
  cursor: not-allowed;
  transform: none;
  filter: none;
}

.stat-card,
.board-panel,
.side-panel .info-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 22px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(8px);
}

.content-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
}

.board-panel {
  padding: 18px;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 16px;
  margin-bottom: 14px;
}

.panel-header h2 {
  margin: 0 0 6px;
}

.panel-header p {
  margin: 0;
  color: var(--muted);
}

.status-bar {
  margin-bottom: 14px;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 12px 14px;
  background: rgba(255, 255, 255, 0.04);
  color: var(--muted);
  font-weight: 700;
}

.stage {
  display: grid;
  grid-template-columns: auto 220px;
  gap: 18px;
  align-items: start;
}

.board-wrap {
  position: relative;
}

#canvas {
  display: block;
  border-radius: 18px;
  border: 1px solid var(--line);
  background: #0b1220;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.03);
  touch-action: none;
}

.side-panel {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.side-panel .info-card {
  padding: 14px;
}

.label {
  font-size: 0.82rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
  font-weight: 800;
}

#next {
  display: block;
  width: 100%;
  max-width: 120px;
  height: auto;
  margin: 0 auto;
  border-radius: 12px;
  background: #0b1220;
}

.help-list {
  color: var(--muted);
  line-height: 1.55;
  font-size: 0.95rem;
}

.feedback.success {
  color: var(--green);
}

.feedback.warning {
  color: var(--gold);
}

.feedback.danger {
  color: var(--danger);
}

.overlay {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: rgba(3, 7, 18, 0.6);
  border-radius: 18px;
}

.overlay.hidden {
  display: none;
}

.overlay-card {
  width: min(360px, calc(100% - 24px));
  border-radius: 20px;
  background: rgba(11, 22, 46, 0.96);
  border: 1px solid var(--line);
  padding: 22px;
  text-align: center;
  box-shadow: var(--shadow);
}

.overlay-card h3 {
  margin: 0 0 10px;
  font-size: 1.8rem;
}

.overlay-card p {
  margin: 0 0 18px;
  color: var(--muted);
  line-height: 1.6;
}

.overlay-actions {
  display: flex;
  gap: 10px;
  justify-content: center;
  flex-wrap: wrap;
}

.controls-mobile {
  display: none;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
  margin-top: 14px;
}

.hidden {
  display: none !important;
}

@media (max-width: 900px) {
  .stage {
    grid-template-columns: 1fr;
  }

  .side-panel {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 780px) {
  .site-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .topbar {
    grid-template-columns: repeat(2, 1fr);
  }

  .panel-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .controls-mobile {
    display: grid;
  }
}

@media (max-width: 560px) {
  .topbar,
  .side-panel {
    grid-template-columns: 1fr;
  }
}