:root {
  --primary-color: #2563eb;
  --secondary-color: #7c3aed;
  --success-color: #10b981;
  --danger-color: #ef4444;
  --warning-color: #f59e0b;
  --bg-color: #0f172a;
  --card-bg: #1e293b;
  --text-color: #f1f5f9;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --hover-color: #475569;
  
  /* Element colors */
  --element-default: #334155;
  --element-hover: #475569;
  --element-ship: #2563eb;
  --element-hit: #ef4444;
  --element-miss: #64748b;
  /* --element-sunk: #7c3aed; */
  --element-sunk: #ef4444;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  background: linear-gradient(135deg, var(--bg-color) 0%, #1a1f3a 100%);
  color: var(--text-color);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.screen {
  display: none;
  width: 100%;
  max-width: 1400px;
  animation: fadeIn 0.3s ease-in;
}

.screen.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.container {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 40px;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.4);
}

h1 {
  font-size: 3rem;
  text-align: center;
  margin-bottom: 10px;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

h2 {
  font-size: 2rem;
  text-align: center;
  margin-bottom: 20px;
}

h3 {
  font-size: 1.2rem;
  margin-bottom: 15px;
  color: var(--text-muted);
}

.subtitle {
  text-align: center;
  color: var(--text-muted);
  margin-bottom: 40px;
  font-size: 1.1rem;
}

/* Buttons */
.btn {
  padding: 14px 28px;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.3);
}

.btn:active {
  transform: translateY(0);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: white;
}

.btn-secondary {
  background: var(--hover-color);
  color: white;
}

.btn-small {
  padding: 8px 16px;
  font-size: 0.875rem;
}

/* Landing Screen */
.room-actions {
  display: flex;
  flex-direction: column;
  gap: 20px;
  align-items: center;
  max-width: 400px;
  margin: 0 auto;
}

.divider {
  color: var(--text-muted);
  font-weight: 600;
}

.join-room-form {
  display: flex;
  gap: 10px;
  width: 100%;
}

input[type="text"] {
  flex: 1;
  padding: 14px;
  font-size: 1rem;
  border: 2px solid var(--border-color);
  border-radius: 8px;
  background: var(--bg-color);
  color: var(--text-color);
  text-transform: uppercase;
  text-align: center;
  letter-spacing: 2px;
}

input[type="text"]:focus {
  outline: none;
  border-color: var(--primary-color);
}

.error {
  margin-top: 20px;
  padding: 12px;
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid var(--danger-color);
  border-radius: 8px;
  color: var(--danger-color);
  text-align: center;
}

.error.hidden {
  display: none;
}

/* Waiting Screen */
.room-code-display {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 15px;
  margin: 30px 0;
}

.room-code-display label {
  font-size: 1.1rem;
  color: var(--text-muted);
}

.code {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: 8px;
  color: var(--primary-color);
  padding: 15px 30px;
  background: var(--bg-color);
  border-radius: 8px;
  font-family: 'Courier New', monospace;
}

.waiting-text {
  text-align: center;
  color: var(--text-muted);
  margin: 20px 0;
  font-size: 1.1rem;
}

.spinner {
  margin: 30px auto;
  width: 50px;
  height: 50px;
  border: 4px solid var(--border-color);
  border-top-color: var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Placement Screen */
.placement-info {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 30px;
  margin-bottom: 30px;
}

.ship-list ul {
  list-style: none;
}

.ship-item {
  display: flex;
  justify-content: space-between;
  padding: 12px;
  margin-bottom: 8px;
  background: var(--bg-color);
  border-radius: 8px;
  border: 2px solid transparent;
  transition: all 0.2s;
}

.ship-item.active {
  border-color: var(--primary-color);
  background: rgba(37, 99, 235, 0.1);
}

.ship-item.placed {
  opacity: 0.5;
  text-decoration: line-through;
}

.ship-name {
  font-weight: 600;
}

.ship-size {
  color: var(--text-muted);
}

.placement-instructions {
  display: flex;
  flex-direction: column;
  gap: 15px;
}

.current-ship {
  font-weight: 600;
  color: var(--primary-color);
  font-size: 1.1rem;
}

#confirm-placement-btn {
  display: block;
  margin: 20px auto 0;
}

/* Periodic Table */
.periodic-table {
  display: grid;
  grid-template-columns: repeat(18, 1fr);
  grid-template-rows: repeat(7, auto) 32px repeat(2, auto);
  gap: 3px;
  margin: 20px auto;
  max-width: 1200px;
  padding: 10px;
  background: var(--bg-color);
  border-radius: 8px;
  position: relative;
}

.table-spacer {
  height: 32px;
  pointer-events: none;
}

.table-connectors {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  overflow: visible;
}

.connector-line {
  stroke: rgba(148, 163, 184, 0.7);
  stroke-width: 2;
}

.element {
  aspect-ratio: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: var(--element-default);
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.2s;
  position: relative;
  border: 2px solid transparent;
  min-width: 40px;
}

.element.row-7 {
  margin-bottom: 16px;
}

.element:hover {
  background: var(--element-hover);
  transform: scale(1.05);
  z-index: 10;
}

.element.disabled {
  cursor: not-allowed;
  opacity: 0.3;
}

.element.disabled:hover {
  transform: none;
  background: var(--element-default);
}

.element-number {
  font-size: 0.6rem;
  color: var(--text-muted);
  position: absolute;
  top: 2px;
  left: 4px;
}

.element-symbol {
  font-size: 1.2rem;
  font-weight: 700;
}

/* Element States */
.element.ship {
  background: var(--element-ship);
  border-color: rgba(37, 99, 235, 0.5);
}

.element.placing {
  background: rgba(37, 99, 235, 0.3);
  border-color: var(--primary-color);
}

.element.dragging {
  opacity: 0.6;
  transform: scale(0.98);
}

.element.hit {
  background: var(--element-hit);
  border-color: rgba(239, 68, 68, 0.5);
}

.element.hit::after {
  content: '🔥';
  position: absolute;
  font-size: 1.5rem;
}

.element.miss {
  background: var(--element-miss);
}

.element.miss::after {
  content: '○';
  position: absolute;
  font-size: 1.5rem;
  color: white;
}

.element.sunk {
  background: var(--element-hit);
  border-color: rgba(239, 68, 68, 0.5);
}

.element.sunk::after {
  content: '🔥';
  position: absolute;
  font-size: 1.5rem;
}

.element.sunk-ship {
  box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.9);
  z-index: 5;
}

/* Game Screen */
.game-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
  padding-bottom: 20px;
  border-bottom: 2px solid var(--border-color);
}

.turn-indicator {
  font-size: 1.3rem;
  font-weight: 700;
  padding: 10px 20px;
  border-radius: 8px;
  background: var(--success-color);
  color: white;
}

.turn-indicator.opponent-turn {
  background: var(--danger-color);
}

.game-status {
  color: var(--text-muted);
  font-size: 1rem;
}

.game-boards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
}

.board-section h3 {
  text-align: center;
  margin-bottom: 15px;
}

.opponent-board .element.ship {
  background: var(--element-default);
  border-color: transparent;
}

/* Game Over Screen */
#game-result {
  font-size: 3rem;
  margin-bottom: 20px;
}

#game-result.win {
  color: var(--success-color);
}

#game-result.lose {
  color: var(--danger-color);
}

#game-result-text {
  text-align: center;
  font-size: 1.2rem;
  color: var(--text-muted);
  margin-bottom: 30px;
}

#new-game-btn {
  display: block;
  margin: 0 auto;
}

/* Responsive */
@media (max-width: 1200px) {
  .game-boards {
    grid-template-columns: 1fr;
  }
  
  .periodic-table {
    max-width: 900px;
  }
}

@media (max-width: 768px) {
  .container {
    padding: 20px;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  .placement-info {
    grid-template-columns: 1fr;
  }
  
  .element {
    min-width: 30px;
  }
  
  .element-symbol {
    font-size: 0.9rem;
  }
  
  .game-header {
    flex-direction: column;
    gap: 15px;
  }
}