:root {
  --bg: #f5f5f7;
  --card-bg: #ffffff;
  --text: #1d1d1f;
  --text-secondary: #6e6e73;
  --border: #e5e5e7;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.1);
  --radius: 12px;
  --accent: #1d1d1f;
  --accent-hover: #3a3a3c;
  --marked: #34c759;
  --marked-text: #ffffff;
  --free-bg: #e8e8ed;
  --bingo-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 700px;
  margin: 0 auto;
  padding: 24px 16px;
}

header {
  text-align: center;
  margin-bottom: 32px;
}

header h1 {
  font-size: 28px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.5px;
}

.subtitle {
  font-size: 15px;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* Views */
.view {
  display: none;
}

.view.active {
  display: block;
}

/* Cards */
.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
  margin-bottom: 16px;
}

.card h2 {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 8px;
}

.card p {
  color: var(--text-secondary);
  font-size: 14px;
  margin-bottom: 20px;
  line-height: 1.5;
}

/* Inputs */
input[type="text"] {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 16px;
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  outline: none;
  transition: border-color 0.2s;
  margin-bottom: 12px;
}

input[type="text"]:focus {
  border-color: var(--accent);
}

input[type="text"]::placeholder {
  color: var(--text-secondary);
}

#join-code {
  text-transform: uppercase;
  letter-spacing: 3px;
  text-align: center;
  font-weight: 600;
  font-size: 18px;
}

/* Buttons */
.btn-primary {
  width: 100%;
  padding: 14px 24px;
  background: var(--accent);
  color: #ffffff;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  transition: background 0.2s, transform 0.1s;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

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

.btn-secondary {
  width: 100%;
  padding: 12px 24px;
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  font-family: var(--font);
  cursor: pointer;
  transition: all 0.2s;
  margin-top: 16px;
}

.btn-secondary:hover {
  border-color: var(--text-secondary);
  color: var(--text);
}

/* Lobby */
.room-code-display {
  text-align: center;
  margin-bottom: 24px;
  padding: 20px;
  background: var(--bg);
  border-radius: 8px;
}

.room-code-label {
  display: block;
  font-size: 12px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 8px;
}

.room-code-value {
  display: block;
  font-size: 36px;
  font-weight: 700;
  letter-spacing: 6px;
  color: var(--text);
}

.player-list {
  list-style: none;
  margin-bottom: 24px;
}

.player-list li {
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
  font-size: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.player-list li:last-child {
  border-bottom: none;
}

.hint {
  text-align: center;
  color: var(--text-secondary);
  font-size: 14px;
  margin-top: 12px;
}

/* Game */
.game-hint {
  text-align: center;
  margin-bottom: 16px;
  padding: 12px 20px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.game-hint p {
  font-size: 14px;
  color: var(--text-secondary);
  font-weight: 500;
}

/* Bingo Card */
.bingo-card {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 6px;
  margin-bottom: 24px;
}

.bingo-cell {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  background: var(--card-bg);
  border-radius: 8px;
  box-shadow: var(--shadow);
  font-size: 11px;
  font-weight: 500;
  padding: 4px;
  cursor: pointer;
  transition: all 0.2s;
  word-break: break-word;
  line-height: 1.3;
  user-select: none;
  position: relative;
  overflow: hidden;
}

.bingo-cell:hover {
  box-shadow: var(--shadow-hover);
}

.bingo-cell.marked {
  background: var(--marked);
  color: var(--marked-text);
  box-shadow: none;
  font-weight: 600;
}

.bingo-cell.free {
  background: var(--free-bg);
  color: var(--text-secondary);
  font-size: 18px;
  cursor: default;
}

.bingo-cell.free.marked {
  background: var(--marked);
  color: var(--marked-text);
}

.bingo-cell.bingo-line {
  animation: bingo-pulse 0.6s ease-in-out infinite alternate;
}

@keyframes bingo-pulse {
  from { transform: scale(1); }
  to { transform: scale(1.05); box-shadow: 0 0 12px rgba(52, 199, 89, 0.5); }
}

/* Bingo Overlay */
.bingo-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  z-index: 100;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(4px);
}

.bingo-overlay.active {
  display: flex;
}

.bingo-overlay-content {
  background: var(--card-bg);
  border-radius: 20px;
  padding: 48px;
  text-align: center;
  max-width: 400px;
  width: 90%;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
  animation: overlay-in 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes overlay-in {
  from { transform: scale(0.8); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

.bingo-overlay-content h1 {
  font-size: 48px;
  background: var(--bingo-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 12px;
}

.bingo-overlay-content p {
  font-size: 18px;
  color: var(--text-secondary);
  margin-bottom: 28px;
}

.bingo-overlay-content .btn-primary {
  width: auto;
  padding: 12px 48px;
}

/* Start view layout */
#view-start {
  display: none;
}

#view-start.active {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

/* Responsive */
@media (min-width: 500px) {
  .bingo-cell {
    font-size: 12px;
    padding: 6px;
  }

  .container {
    padding: 40px 24px;
  }
}

@media (min-width: 640px) {
  .bingo-cell {
    font-size: 13px;
    padding: 8px;
  }

  #view-start.active {
    grid-template-columns: 1fr 1fr;
  }
}