:root {
  color-scheme: dark;
  --bg: #07101f;
  --bg-secondary: #0d1a31;
  --card: rgba(13, 26, 49, 0.88);
  --card-border: rgba(121, 155, 255, 0.18);
  --text: #f5f8ff;
  --muted: #9cb2dd;
  --cyan: #33dcff;
  --violet: #7e5fff;
  --green: #24d18b;
  --red: #ff6b81;
  --shadow: 0 24px 60px rgba(2, 11, 24, 0.55);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: 'Inter', system-ui, sans-serif;
  background:
    radial-gradient(circle at top left, rgba(51, 220, 255, 0.14), transparent 28%),
    radial-gradient(circle at top right, rgba(126, 95, 255, 0.2), transparent 30%),
    linear-gradient(180deg, #091221 0%, #060c17 100%);
  color: var(--text);
}

button,
input {
  font: inherit;
}

button {
  border: 0;
  cursor: pointer;
  transition: transform 0.15s ease, opacity 0.15s ease, background 0.15s ease;
}

button:hover {
  transform: translateY(-1px);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
  transform: none;
}

.shell {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  padding: 32px 0 64px;
}

.card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: 28px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(20px);
}

.hero {
  padding: 36px;
  margin-bottom: 20px;
}

.hero h1 {
  margin: 8px 0 12px;
  font-size: clamp(2.3rem, 4vw, 4.2rem);
}

.eyebrow {
  margin: 0;
  color: var(--cyan);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.subcopy,
.panel-header p,
label span,
.status-card p,
.player-presence,
#join-description {
  color: var(--muted);
}

.alerts {
  display: grid;
  gap: 12px;
  margin-bottom: 20px;
}

.alert {
  padding: 14px 18px;
  border-radius: 18px;
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.alert.error {
  background: rgba(255, 107, 129, 0.12);
  color: #ffdbe1;
}

.alert.success {
  background: rgba(36, 209, 139, 0.12);
  color: #d6fff0;
}

.panel {
  display: none;
  padding: 28px;
}

.panel.active {
  display: block;
}

.hidden {
  display: none !important;
}

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

.stacked-form {
  display: grid;
  gap: 16px;
  margin-top: 24px;
}

label {
  display: grid;
  gap: 8px;
}

input {
  width: 100%;
  border-radius: 16px;
  border: 1px solid rgba(168, 188, 255, 0.18);
  background: rgba(4, 12, 24, 0.8);
  color: var(--text);
  padding: 15px 16px;
  outline: none;
}

input:focus {
  border-color: rgba(51, 220, 255, 0.85);
  box-shadow: 0 0 0 4px rgba(51, 220, 255, 0.12);
}

.primary,
.secondary,
.ghost {
  border-radius: 16px;
  padding: 14px 18px;
  font-weight: 700;
}

.primary {
  background: linear-gradient(135deg, var(--cyan), var(--violet));
  color: #051120;
}

.secondary {
  background: rgba(51, 220, 255, 0.16);
  color: var(--text);
}

.ghost {
  background: rgba(255, 255, 255, 0.06);
  color: var(--text);
}

.game-topbar {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  align-items: center;
}

.invite-box {
  margin-top: 22px;
  display: grid;
  gap: 10px;
}

.invite-controls {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 12px;
}

.status-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin: 22px 0;
}

.status-card,
.player-card {
  border-radius: 20px;
  padding: 18px;
  background: rgba(6, 16, 31, 0.84);
  border: 1px solid rgba(151, 175, 255, 0.14);
}

.status-card strong {
  font-size: 1.05rem;
}

.players {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  margin-bottom: 24px;
}

.player-card {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.player-symbol {
  margin: 0 0 4px;
  color: var(--cyan);
  font-weight: 700;
}

.player-card.offline .player-presence {
  color: #ffc675;
}

.board {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.cell {
  aspect-ratio: 1;
  border-radius: 24px;
  background: rgba(3, 12, 24, 0.95);
  color: var(--text);
  font-size: clamp(2.4rem, 6vw, 5rem);
  font-weight: 800;
  border: 1px solid rgba(124, 146, 227, 0.18);
}

.cell.x {
  color: var(--cyan);
}

.cell.o {
  color: #b890ff;
}

.cell.winning {
  box-shadow: inset 0 0 0 2px rgba(36, 209, 139, 0.5), 0 0 0 4px rgba(36, 209, 139, 0.14);
}

@media (max-width: 820px) {
  .shell {
    width: min(100% - 20px, 720px);
  }

  .status-grid,
  .players,
  .invite-controls {
    grid-template-columns: 1fr;
  }

  .game-topbar {
    flex-direction: column;
    align-items: flex-start;
  }
}