:root {
  --bg-top: #1a2f1f;
  --bg-bottom: #0d1811;
  --panel: rgba(255, 255, 255, 0.06);
  --panel-border: rgba(255, 255, 255, 0.12);
  --text: #f4f1ea;
  --muted: #a8b5a0;
  --wood: #d2a679;
  --wood-dark: #b8895a;
  --line: rgba(60, 36, 16, 0.55);
  --black-stone: #1a1a1a;
  --white-stone: #f3f3f0;
  --win: #3ebd93;
  --accent: #e8c27a;
  --shadow: 0 24px 48px rgba(3, 12, 8, 0.45);
  --radius: 18px;
  --board-max: min(92vw, 560px);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Trebuchet MS", "Segoe UI", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 18% 12%, rgba(232, 194, 122, 0.14), transparent 36%),
    radial-gradient(circle at 88% 8%, rgba(62, 189, 147, 0.1), transparent 28%),
    linear-gradient(160deg, var(--bg-top), var(--bg-bottom));
}

.app {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 20px 12px 28px;
}

.game {
  width: min(100%, 620px);
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: calc(var(--radius) + 6px);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
  padding: 22px 18px 16px;
}

.header {
  text-align: center;
  margin-bottom: 14px;
}

.header h1 {
  margin: 0;
  font-size: clamp(1.7rem, 4.5vw, 2.1rem);
  letter-spacing: 0.06em;
}

.subtitle {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.controls-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 10px 18px;
  margin-bottom: 14px;
}

.mode-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
}

.mode-bar[hidden] {
  display: none;
}

.mode-label {
  color: var(--muted);
  font-size: 0.88rem;
  font-weight: 700;
}

.mode-select {
  appearance: none;
  min-width: min(100%, 220px);
  padding: 8px 34px 8px 12px;
  border-radius: 10px;
  border: 1px solid var(--panel-border);
  background:
    linear-gradient(45deg, transparent 50%, var(--muted) 50%) calc(100% - 14px) / 6px 6px no-repeat,
    linear-gradient(135deg, var(--muted) 50%, transparent 50%) calc(100% - 9px) / 6px 6px no-repeat,
    rgba(0, 0, 0, 0.28);
  color: var(--text);
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
}

.mode-select:focus-visible {
  outline: 2px solid #7cc4f0;
  outline-offset: 2px;
}

.mode-select-sm {
  min-width: min(100%, 130px);
}

.spectator-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 10px 14px;
  margin: 0 0 14px;
  padding: 12px 10px;
  border-radius: 12px;
  border: 1px solid var(--panel-border);
  background: rgba(0, 0, 0, 0.18);
}

.spectator-bar[hidden] {
  display: none;
}

.spectator-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
}

.btn-compact {
  min-height: 38px;
  padding: 0 12px;
  font-size: 0.85rem;
}

.btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.scoreboard {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-bottom: 12px;
}

.score-card {
  background: rgba(0, 0, 0, 0.22);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 10px 8px;
  text-align: center;
}

.score-label {
  display: block;
  color: var(--muted);
  font-size: 0.78rem;
  margin-bottom: 4px;
}

.score-value {
  font-size: 1.3rem;
  font-weight: 700;
}

.score-black .score-value {
  color: #d0d0d0;
}

.score-white .score-value {
  color: #fff;
}

.status {
  min-height: 1.5rem;
  margin: 0 0 12px;
  text-align: center;
  font-size: 1.02rem;
  font-weight: 600;
}

.status.is-win {
  color: var(--win);
}

.status.is-draw {
  color: var(--muted);
}

.status.is-thinking {
  color: var(--accent);
}

.board-shell {
  width: var(--board-max);
  max-width: 100%;
  margin: 0 auto 16px;
  padding: 3.2%;
  border-radius: 12px;
  background:
    linear-gradient(145deg, var(--wood) 0%, var(--wood-dark) 100%);
  box-shadow:
    inset 0 0 0 2px rgba(90, 50, 20, 0.25),
    0 10px 24px rgba(0, 0, 0, 0.28);
}

.board {
  position: relative;
  display: grid;
  grid-template-columns: repeat(15, 1fr);
  grid-template-rows: repeat(15, 1fr);
  aspect-ratio: 1 / 1;
  width: 100%;
}

/* Lines pass through intersection centres (inset by half a cell). */
.board-lines {
  position: absolute;
  inset: calc(100% / 30);
  pointer-events: none;
  z-index: 0;
  background-image:
    linear-gradient(to right, var(--line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line) 1px, transparent 1px);
  background-size: calc(100% / 14) calc(100% / 14);
  background-position: 0 0;
}

/* Star points (hoshi) on a standard 15×15 board */
.board-lines::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(circle, rgba(60, 36, 16, 0.8) 2.2px, transparent 2.6px),
    radial-gradient(circle, rgba(60, 36, 16, 0.8) 2.2px, transparent 2.6px),
    radial-gradient(circle, rgba(60, 36, 16, 0.8) 2.2px, transparent 2.6px),
    radial-gradient(circle, rgba(60, 36, 16, 0.8) 2.2px, transparent 2.6px),
    radial-gradient(circle, rgba(60, 36, 16, 0.8) 2.2px, transparent 2.6px);
  background-size: 100% 100%;
  background-position:
    calc(100% / 14 * 3) calc(100% / 14 * 3),
    calc(100% / 14 * 11) calc(100% / 14 * 3),
    calc(100% / 14 * 7) calc(100% / 14 * 7),
    calc(100% / 14 * 3) calc(100% / 14 * 11),
    calc(100% / 14 * 11) calc(100% / 14 * 11);
  background-repeat: no-repeat;
}

.intersection {
  appearance: none;
  border: none;
  padding: 0;
  margin: 0;
  background: transparent;
  position: relative;
  cursor: pointer;
  z-index: 1;
}

.intersection:disabled {
  cursor: default;
}

.intersection:focus-visible {
  outline: none;
}

.intersection:focus-visible::after {
  content: "";
  position: absolute;
  inset: 18%;
  border: 2px solid #7cc4f0;
  border-radius: 50%;
  pointer-events: none;
}

.intersection:hover:not(:disabled):not(.has-stone)::before {
  content: "";
  position: absolute;
  inset: 22%;
  border-radius: 50%;
  background: rgba(0, 0, 0, 0.18);
}

.stone {
  position: absolute;
  inset: 12%;
  border-radius: 50%;
  pointer-events: none;
  box-shadow: 1px 2px 3px rgba(0, 0, 0, 0.35);
}

.stone-black {
  background:
    radial-gradient(circle at 32% 28%, #555 0%, var(--black-stone) 55%, #000 100%);
}

.stone-white {
  background:
    radial-gradient(circle at 32% 28%, #fff 0%, var(--white-stone) 55%, #cfcfc8 100%);
  box-shadow:
    1px 2px 3px rgba(0, 0, 0, 0.28),
    inset 0 0 0 1px rgba(0, 0, 0, 0.08);
}

.intersection.is-winning .stone {
  box-shadow:
    0 0 0 2px rgba(62, 189, 147, 0.95),
    0 0 10px rgba(62, 189, 147, 0.55),
    1px 2px 3px rgba(0, 0, 0, 0.35);
}

.intersection.is-last .stone::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  width: 18%;
  height: 18%;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  background: #c0392b;
}

.actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.btn {
  appearance: none;
  border: none;
  border-radius: 12px;
  min-height: 46px;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.08s ease, opacity 0.15s ease;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  color: #1a2f1f;
  background: linear-gradient(180deg, #f0d59a, #e8c27a);
}

.btn-secondary {
  color: var(--text);
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid var(--panel-border);
}

.btn:focus-visible {
  outline: 2px solid #7cc4f0;
  outline-offset: 2px;
}

.hint {
  margin: 12px 0 0;
  text-align: center;
  color: var(--muted);
  font-size: 0.8rem;
  line-height: 1.4;
}

.board.is-locked {
  pointer-events: none;
}

@media (max-width: 480px) {
  .game {
    padding: 18px 12px 14px;
  }

  .actions {
    grid-template-columns: 1fr;
  }

  .mode-bar {
    flex-direction: column;
    gap: 6px;
  }

  .mode-select {
    width: 100%;
  }
}