:root {
  --bg: #0a0a0a;
  --card: #1a1a1a;
  --text: #e0e0e0;
  --text-dim: #999;
  --accent: #00d9ff;
  --accent-hover: #00b8d4;
  --secondary: #ff6b9d;
  --border: #333;
  --node-primary: #00d9ff;
  --node-secondary: #ff6b9d;
  --node-tertiary: #7c4dff;
  --node-quaternary: #ffd600;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  background: var(--bg);
  color: var(--text);
  overflow: hidden;
  height: 100vh;
}

#app {
  height: 100vh;
  display: flex;
  flex-direction: column;
}

.main-nav {
  background: var(--card);
  border-bottom: 2px solid var(--border);
  padding: 0 40px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
  flex-shrink: 0;
}

.nav-brand {
  font-size: 24px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--accent), var(--secondary));
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.nav-info {
  color: var(--text-dim);
  font-size: 14px;
}

.nav-controls {
  display: flex;
  align-items: center;
  gap: 20px;
}

.theme-select {
  padding: 8px 16px;
  background: var(--bg);
  color: var(--text);
  border: 2px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
  cursor: pointer;
  transition: border-color 0.3s;
}

.theme-select:focus {
  outline: none;
  border-color: var(--accent);
}

.theme-select option {
  background: var(--bg);
  color: var(--text);
}

.screen {
  display: none;
  flex: 1;
  overflow: hidden;
}

.screen.active {
  display: flex;
  flex-direction: column;
}

#input-screen {
  justify-content: center;
  align-items: center;
  padding: 40px;
}

.input-container {
  max-width: 700px;
  width: 100%;
  text-align: center;
}

.input-container h1 {
  font-size: 48px;
  color: var(--accent);
  margin-bottom: 20px;
}

.input-container p {
  color: var(--text-dim);
  font-size: 18px;
  margin-bottom: 40px;
  line-height: 1.6;
}

#topic-input {
  width: 100%;
  padding: 20px;
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 12px;
  color: var(--text);
  font-size: 18px;
  margin-bottom: 20px;
  transition: border-color 0.3s;
}

#topic-input:focus {
  outline: none;
  border-color: var(--accent);
}

.btn-primary {
  padding: 15px 50px;
  background: var(--accent);
  color: #000;
  border: none;
  border-radius: 8px;
  font-size: 18px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
}

.btn-secondary {
  padding: 10px 20px;
  background: transparent;
  color: var(--text);
  border: 2px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
}

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

.examples {
  margin-top: 30px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  align-items: center;
}

.example-label {
  color: var(--text-dim);
  font-size: 14px;
  margin-right: 10px;
}

.example-btn {
  padding: 8px 16px;
  background: var(--card);
  color: var(--text-dim);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
  cursor: pointer;
  transition: all 0.3s;
}

.example-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

#loading-screen {
  justify-content: center;
  align-items: center;
}

.loading-content {
  text-align: center;
}

.spinner {
  width: 80px;
  height: 80px;
  border: 4px solid var(--border);
  border-top: 4px solid var(--accent);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin: 0 auto 30px;
}

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

#loading-text {
  font-size: 20px;
  color: var(--accent);
}

#explorer-screen {
  position: relative;
}

.explorer-controls {
  position: absolute;
  top: 20px;
  left: 20px;
  z-index: 10;
  display: flex;
  gap: 10px;
}

#canvas-container {
  flex: 1;
  position: relative;
  overflow: hidden;
  background: #0a0a0a;
}

#canvas-container.theme-dark {
  background: #0a0a0a;
}

#canvas-container.theme-light {
  background: #f5f5f5;
}

#canvas-container.theme-dark-blue {
  background: linear-gradient(to bottom, #0a0a0a 0%, #001a33 100%);
}

#canvas-container.theme-light-gray {
  background: linear-gradient(to bottom, #f5f5f5 0%, #cccccc 100%);
}

#node-canvas {
  width: 100%;
  height: 100%;
  cursor: grab;
  background: transparent;
}

#node-canvas.dragging {
  cursor: grabbing;
}

.node-panel {
  position: absolute;
  top: 20px;
  right: 20px;
  width: 400px;
  max-height: calc(100vh - 140px);
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 30px;
  overflow-y: auto;
  z-index: 100;
  transition: transform 0.3s;
}

.node-panel.hidden {
  transform: translateX(450px);
}

.close-btn {
  position: absolute;
  top: 15px;
  right: 15px;
  width: 30px;
  height: 30px;
  background: transparent;
  border: none;
  color: var(--text-dim);
  font-size: 24px;
  cursor: pointer;
  transition: color 0.3s;
}

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

#panel-title {
  color: var(--accent);
  font-size: 24px;
  margin-bottom: 20px;
  padding-right: 30px;
}

#panel-content {
  color: var(--text);
  font-size: 16px;
  line-height: 1.8;
  margin-bottom: 30px;
}

#panel-content p {
  margin-bottom: 15px;
}

#panel-branches h3 {
  color: var(--secondary);
  font-size: 18px;
  margin-bottom: 15px;
}

#branch-buttons {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.branch-btn {
  padding: 12px 20px;
  background: var(--bg);
  color: var(--text);
  border: 2px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  text-align: left;
  cursor: pointer;
  transition: all 0.3s;
}

.branch-btn:hover {
  border-color: var(--accent);
  background: rgba(0, 217, 255, 0.1);
  transform: translateX(5px);
}

.branch-btn::before {
  content: '→ ';
  color: var(--accent);
  margin-right: 8px;
}

@media (max-width: 768px) {
  .main-nav {
    padding: 0 20px;
  }

  .input-container h1 {
    font-size: 32px;
  }

  .node-panel {
    width: calc(100% - 40px);
    max-height: 50vh;
    top: auto;
    bottom: 20px;
  }

  .node-panel.hidden {
    transform: translateY(calc(100% + 40px));
  }

  .explorer-controls {
    flex-direction: column;
  }
}