:root {
  color-scheme: dark;
  font-family:
    Pretendard, "Noto Sans KR", Inter, ui-sans-serif, system-ui, -apple-system,
    BlinkMacSystemFont, "Segoe UI", sans-serif;
  --bg: #090d16;
  --panel: rgba(19, 26, 42, 0.86);
  --line: rgba(255, 255, 255, 0.1);
  --text: #f6f8ff;
  --muted: #9ca8bf;
  --accent: #72f1b8;
  --danger: #ff6b86;
}

* {
  box-sizing: border-box;
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at 18% 14%, rgba(71, 96, 255, 0.18), transparent 35%),
    radial-gradient(circle at 82% 72%, rgba(35, 226, 166, 0.1), transparent 36%),
    var(--bg);
}

button {
  font: inherit;
}

.game-shell {
  width: min(94vw, 820px);
  margin: 0 auto;
  padding: 34px 0 28px;
}

.hero,
.scoreboard,
.status-panel,
footer {
  display: flex;
  align-items: center;
}

.hero {
  justify-content: space-between;
  gap: 20px;
}

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

.eyebrow {
  margin: 0 0 7px;
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.18em;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 7vw, 3.65rem);
  letter-spacing: -0.06em;
  line-height: 0.95;
}

h1 span {
  margin-left: 10px;
  color: var(--muted);
  font-size: 0.34em;
  letter-spacing: -0.02em;
  vertical-align: middle;
}

.ghost-button,
#retry-button {
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--text);
  background: rgba(255, 255, 255, 0.05);
  cursor: pointer;
  transition: 150ms ease;
}

.ghost-button {
  padding: 10px 16px;
}

.ghost-button:hover,
.ghost-button:focus-visible {
  border-color: rgba(114, 241, 184, 0.6);
  background: rgba(114, 241, 184, 0.1);
}

.rule-card {
  margin-top: 24px;
  padding: 18px 20px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--panel);
  backdrop-filter: blur(16px);
}

.rule-card p {
  margin: 0;
  color: #d8dfed;
  line-height: 1.65;
}

.rule-card strong {
  color: #fff;
}

.rule-examples {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
}

.rule-examples span {
  padding: 6px 10px;
  border-radius: 999px;
  color: var(--muted);
  background: rgba(255, 255, 255, 0.05);
  font-size: 0.8rem;
}

.rule-examples b {
  color: var(--accent);
}

.rule-examples i {
  padding: 0 3px;
  color: #fff;
  font-style: normal;
}

.scoreboard {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin: 14px 0;
}

.scoreboard article {
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.035);
}

.scoreboard span {
  display: block;
  margin-bottom: 3px;
  color: var(--muted);
  font-size: 0.7rem;
}

.scoreboard strong {
  font-size: 1.25rem;
  font-variant-numeric: tabular-nums;
}

.board-wrap {
  position: relative;
}

.board-prompt {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 4px 2px 10px;
  color: #dfe6f5;
  font-size: 0.86rem;
}

.board-prompt span {
  padding: 4px 8px;
  border-radius: 999px;
  color: #07120e;
  background: var(--accent);
  font-size: 0.65rem;
  font-weight: 900;
  letter-spacing: 0.08em;
}

.board {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: clamp(4px, 1vw, 8px);
  padding: clamp(8px, 1.8vw, 14px);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 22px;
  background: rgba(10, 15, 27, 0.82);
  box-shadow:
    0 24px 80px rgba(0, 0, 0, 0.35),
    inset 0 1px 0 rgba(255, 255, 255, 0.05);
}

.cell {
  position: relative;
  display: grid;
  aspect-ratio: 1;
  min-width: 0;
  place-items: center;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: clamp(8px, 1.6vw, 14px);
  color: var(--text);
  background: rgba(255, 255, 255, 0.028);
  cursor: default;
  transition:
    transform 130ms ease,
    border-color 130ms ease,
    background 130ms ease,
    box-shadow 130ms ease;
}

.cell.empty {
  cursor: pointer;
}

.cell.empty::before {
  content: "+";
  color: rgba(114, 241, 184, 0.22);
  font-size: clamp(1rem, 3vw, 1.5rem);
  transition: 120ms ease;
}

.cell.empty:hover,
.cell.empty:focus-visible,
.cell.preview-target {
  border-color: rgba(114, 241, 184, 0.42);
  background: rgba(114, 241, 184, 0.07);
  outline: none;
}

.cell.empty:hover::before,
.cell.empty:focus-visible::before,
.cell.preview-target::before {
  color: var(--accent);
}

.cell.starter-cell {
  border-color: rgba(114, 241, 184, 0.55);
  background: rgba(114, 241, 184, 0.08);
  box-shadow: 0 0 0 3px rgba(114, 241, 184, 0.06);
  animation: starter-pulse 1.7s ease-in-out infinite;
}

.cell.starter-cell::before {
  content: "1";
  color: var(--accent);
  font-weight: 850;
}

@keyframes starter-pulse {
  0%,
  100% {
    border-color: rgba(114, 241, 184, 0.56);
    box-shadow: inset 0 0 0 1px rgba(114, 241, 184, 0.08), 0 0 0 rgba(114, 241, 184, 0);
  }
  50% {
    border-color: rgba(114, 241, 184, 0.95);
    box-shadow: inset 0 0 0 1px rgba(114, 241, 184, 0.28), 0 0 18px rgba(114, 241, 184, 0.18);
  }
}

.cell.occupied {
  border-color: hsl(var(--tile-hue) 78% 68% / 0.46);
  background:
    linear-gradient(
      145deg,
      hsl(var(--tile-hue) 65% 58% / 0.35),
      hsl(var(--tile-hue) 68% 34% / 0.26)
    ),
    rgba(255, 255, 255, 0.035);
  box-shadow: inset 0 0 22px hsl(var(--tile-hue) 70% 50% / 0.1);
}

.cell .rank {
  font-size: clamp(1.08rem, 4.5vw, 2.2rem);
  font-weight: 850;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.06em;
  line-height: 1;
}

.cell .group-count {
  position: absolute;
  right: 5px;
  bottom: 4px;
  color: rgba(255, 255, 255, 0.62);
  font-size: clamp(0.48rem, 1.45vw, 0.68rem);
  font-weight: 750;
}

.cell.overloaded {
  border-color: rgba(255, 107, 134, 0.8);
  background:
    repeating-linear-gradient(
      135deg,
      rgba(255, 107, 134, 0.17) 0,
      rgba(255, 107, 134, 0.17) 7px,
      rgba(255, 107, 134, 0.06) 7px,
      rgba(255, 107, 134, 0.06) 14px
    ),
    rgba(74, 17, 34, 0.55);
}

.cell.overloaded .group-count {
  color: #ff9caf;
}

.cell.preview-merge {
  border-color: rgba(114, 241, 184, 0.95);
  box-shadow:
    0 0 0 2px rgba(114, 241, 184, 0.18),
    0 0 24px rgba(114, 241, 184, 0.16);
  transform: translateY(-2px);
}

.cell.preview-overload {
  border-color: var(--danger);
  box-shadow: 0 0 22px rgba(255, 107, 134, 0.22);
}

.cell.merge-pop {
  animation: merge-pop 360ms cubic-bezier(0.2, 1.5, 0.45, 1);
}

@keyframes merge-pop {
  0% {
    transform: scale(0.68);
    filter: brightness(1.8);
  }
  70% {
    transform: scale(1.1);
  }
  100% {
    transform: scale(1);
  }
}

.status-panel {
  gap: 13px;
  min-height: 74px;
  margin-top: 12px;
  padding: 13px 16px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--panel);
}

.status-panel[data-tone="merge"] {
  border-color: rgba(114, 241, 184, 0.38);
}

.status-panel[data-tone="danger"] {
  border-color: rgba(255, 107, 134, 0.45);
}

.status-icon {
  display: grid;
  flex: 0 0 42px;
  height: 42px;
  place-items: center;
  border-radius: 13px;
  color: var(--accent);
  background: rgba(114, 241, 184, 0.1);
  font-size: 1.4rem;
  font-weight: 850;
}

.status-panel[data-tone="danger"] .status-icon {
  color: var(--danger);
  background: rgba(255, 107, 134, 0.1);
}

.status-panel p {
  margin: 0 0 4px;
  font-weight: 750;
}

.status-panel span {
  color: var(--muted);
  font-size: 0.8rem;
  line-height: 1.45;
}

.game-over {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  place-items: center;
  border-radius: 22px;
  background: rgba(7, 10, 18, 0.9);
  backdrop-filter: blur(9px);
}

.game-over[hidden] {
  display: none;
}

.game-over p {
  margin: 0;
  color: var(--muted);
}

.game-over strong {
  margin: 7px 0 18px;
  font-size: 2.25rem;
}

#retry-button {
  padding: 11px 20px;
  border-color: rgba(114, 241, 184, 0.4);
  background: rgba(114, 241, 184, 0.12);
}

footer {
  justify-content: center;
  gap: 16px;
  margin-top: 18px;
  color: var(--muted);
  font-size: 0.74rem;
}

.onboarding-dialog {
  width: min(92vw, 720px);
  max-height: min(92vh, 880px);
  padding: 0;
  overflow: auto;
  border: 0;
  border-radius: 26px;
  color: var(--text);
  background: transparent;
  box-shadow: 0 38px 110px rgba(0, 0, 0, 0.58);
}

.onboarding-dialog::backdrop {
  background:
    radial-gradient(circle at 28% 16%, rgba(71, 96, 255, 0.25), transparent 42%),
    rgba(4, 7, 13, 0.86);
  backdrop-filter: blur(10px);
}

.onboarding-card {
  padding: clamp(24px, 5vw, 42px);
  border: 1px solid rgba(255, 255, 255, 0.13);
  border-radius: 26px;
  background:
    linear-gradient(145deg, rgba(29, 39, 68, 0.98), rgba(10, 15, 27, 0.99));
}

.onboarding-kicker {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.14em;
}

.onboarding-card h2 {
  margin: 0;
  font-size: clamp(1.75rem, 5vw, 2.65rem);
  letter-spacing: -0.045em;
}

.onboarding-description {
  margin: 10px 0 24px;
  color: #cbd4e6;
  line-height: 1.6;
}

.onboarding-rules {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.onboarding-rules li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 14px;
  padding: 15px;
  border: 1px solid rgba(255, 255, 255, 0.09);
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.035);
}

.rule-step {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border-radius: 11px;
  color: #07120e;
  background: var(--accent);
  font-weight: 900;
}

.rule-step.danger {
  color: #fff;
  background: var(--danger);
}

.onboarding-rules strong {
  display: block;
  margin-bottom: 4px;
}

.onboarding-rules p {
  margin: 0;
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.45;
}

.mini-example {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 5px;
  min-width: 158px;
}

.mini-example i {
  margin: 0 3px;
  color: var(--muted);
  font-style: normal;
}

.mini-example b {
  margin-left: 4px;
  color: var(--danger);
  font-size: 0.72rem;
}

.mini-cell {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border: 1px solid rgba(114, 241, 184, 0.4);
  border-radius: 10px;
  color: #fff;
  background: rgba(114, 241, 184, 0.12);
  font-weight: 850;
}

.mini-cell.empty {
  color: var(--accent);
  background: rgba(255, 255, 255, 0.025);
}

.mini-cell.result {
  color: #07120e;
  background: var(--accent);
}

.mini-cell.blocked {
  border-color: rgba(255, 107, 134, 0.72);
  background:
    repeating-linear-gradient(
      135deg,
      rgba(255, 107, 134, 0.22) 0,
      rgba(255, 107, 134, 0.22) 5px,
      rgba(255, 107, 134, 0.07) 5px,
      rgba(255, 107, 134, 0.07) 10px
    ),
    rgba(74, 17, 34, 0.6);
}

.connection-note {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin: 16px 0;
  color: var(--muted);
  font-size: 0.78rem;
}

.connection-note > span:first-child {
  color: var(--accent);
  font-size: 1.2rem;
}

.connection-note strong {
  color: #e9eef8;
}

.primary-button {
  width: 100%;
  padding: 14px 18px;
  border: 0;
  border-radius: 15px;
  color: #07120e;
  background: var(--accent);
  cursor: pointer;
  font-weight: 900;
  box-shadow: 0 12px 30px rgba(114, 241, 184, 0.16);
  transition: filter 130ms ease, transform 130ms ease;
}

.primary-button:hover,
.primary-button:focus-visible {
  filter: brightness(1.08);
  outline: 3px solid rgba(114, 241, 184, 0.25);
  transform: translateY(-1px);
}

.onboarding-return-hint {
  margin: 10px 0 0;
  color: #76839a;
  font-size: 0.7rem;
  text-align: center;
}

.footer-danger::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  margin-right: 7px;
  border-radius: 999px;
  background: var(--danger);
  vertical-align: 1px;
}

@media (max-width: 620px) {
  .game-shell {
    width: min(96vw, 620px);
    padding-top: 20px;
  }

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

  .hero {
    align-items: flex-start;
  }

  .hero-actions {
    flex-direction: column;
  }

  .ghost-button {
    padding: 8px 12px;
    font-size: 0.76rem;
  }

  .rule-card {
    padding: 14px 15px;
  }

  .rule-card p {
    font-size: 0.88rem;
  }

  .board-prompt {
    align-items: flex-start;
    font-size: 0.77rem;
    line-height: 1.45;
  }

  .board {
    border-radius: 16px;
  }

  .cell {
    border-radius: 8px;
  }

  footer {
    flex-direction: column;
    gap: 5px;
  }

  .onboarding-card {
    padding: 22px 16px;
  }

  .onboarding-description {
    margin-bottom: 18px;
    font-size: 0.88rem;
  }

  .onboarding-rules li {
    grid-template-columns: auto minmax(0, 1fr);
    gap: 10px;
    padding: 12px;
  }

  .mini-example {
    grid-column: 2;
    justify-content: flex-start;
    min-width: 0;
  }

  .mini-cell {
    width: 34px;
    height: 34px;
  }

  .connection-note {
    flex-wrap: wrap;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}