:root {
  --bg-color: #1e1e1e;
  --sidebar-bg: #252526;
  --text-color: #d4d4d4;
  --accent-color: #007acc;
  --accent-hover: #0098ff;
  --secondary-bg: #3c3c3c;
  --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  margin: 0;
  padding: 0;
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: var(--font-family);
  overflow: hidden;
}

#app {
  display: flex;
  height: 100vh;
  width: 100vw;
}

#game-container {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #1e1e1e; /* Dark background for game area */
}

#sidebar {
  width: 300px;
  background-color: var(--sidebar-bg);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 20px;
  box-shadow: -2px 0 5px rgba(0,0,0,0.5);
  overflow-y: auto;
}

.header h1 {
  margin: 0 0 10px 0;
  font-size: 1.5rem;
  font-weight: 600;
  background: linear-gradient(45deg, #007acc, #00d4ff);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.status {
  padding: 10px;
  background-color: var(--secondary-bg);
  border-radius: 4px;
  text-align: center;
  font-weight: bold;
}

.controls {
  display: flex;
  gap: 10px;
}

.btn {
  flex: 1;
  padding: 10px;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  font-weight: 600;
  transition: background-color 0.2s, transform 0.1s;
}

.btn:active {
  transform: translateY(1px);
}

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

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

.btn.secondary {
  background-color: var(--secondary-bg);
  color: var(--text-color);
}

.btn.secondary:hover {
  background-color: #4d4d4d;
}

.btn.small {
  font-size: 0.8rem;
  padding: 5px 10px;
}

.settings {
  display: flex;
  flex-direction: column;
  gap: 15px;
  padding: 15px;
  background-color: rgba(0,0,0,0.2);
  border-radius: 8px;
}

.setting-group {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.setting-group label {
  font-size: 0.9rem;
  color: #aaa;
}

select {
  padding: 8px;
  background-color: var(--secondary-bg);
  color: var(--text-color);
  border: 1px solid #555;
  border-radius: 4px;
}

.history-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  background-color: rgba(0,0,0,0.2);
  border-radius: 8px;
  padding: 10px;
  min-height: 150px;
}

.history-container h3 {
  margin: 0 0 10px 0;
  font-size: 1rem;
}

.pgn-display {
  flex: 1;
  font-family: 'Courier New', Courier, monospace;
  font-size: 0.9rem;
  white-space: pre-wrap;
  overflow-y: auto;
  color: #ccc;
  line-height: 1.4;
}

@media (max-width: 800px) {
  #app {
    flex-direction: column;
  }

  #sidebar {
    width: 100%;
    height: 300px; /* Fixed height for mobile sidebar */
    box-shadow: 0 -2px 5px rgba(0,0,0,0.5);
  }
}