/* CSS 变量定义 - 支持明暗主题 */
:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border-color: #e2e8f0;
  --border-hover: #cbd5e1;
  --accent-color: #3b82f6;
  --accent-hover: #2563eb;
  --success-color: #10b981;
  --error-color: #ef4444;
  --warning-color: #f59e0b;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --border-hover: #475569;
  --accent-color: #60a5fa;
  --accent-hover: #3b82f6;
  --success-color: #34d399;
  --error-color: #f87171;
  --warning-color: #fbbf24;
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color 0.3s ease, color 0.3s ease;
  overflow-x: hidden;
}

.app-container {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
}

.header {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 2rem;
  position: sticky;
  top: 0;
  z-index: 100;
}

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

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent-color);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.header-controls {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.new-chat-btn, .theme-toggle {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.5rem 1rem;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 500;
}

.new-chat-btn:hover, .theme-toggle:hover {
  background: var(--accent-color);
  color: white;
  transform: translateY(-1px);
}

.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 2rem;
  gap: 2rem;
}

.welcome-container {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  opacity: 1;
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.welcome-container.hidden {
  opacity: 0;
  transform: translateY(-20px);
  pointer-events: none;
}

.welcome-text {
  font-size: 3rem;
  font-weight: 700;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1rem;
  min-height: 4rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.welcome-subtitle {
  font-size: 1.2rem;
  color: var(--text-secondary);
}

.chat-container {
  flex: 1;
  display: none;
  flex-direction: column;
  max-height: 60vh;
  overflow-y: auto;
  padding: 1rem;
  background: var(--bg-secondary);
  border-radius: 1rem;
  border: 1px solid var(--border-color);
}

.chat-container.active {
  display: flex;
}

.messages {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.message {
  display: flex;
  gap: 0.75rem;
}

.message.user {
  flex-direction: row-reverse;
}

.message-avatar {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  flex-shrink: 0;
}

.message.user .message-avatar {
  background: var(--gradient-secondary);
  color: white;
}

.message.assistant .message-avatar {
  background: var(--gradient-primary);
  color: white;
}

.message-content {
  flex: 1;
  background: var(--bg-tertiary);
  padding: 1rem;
  border-radius: 1rem;
  border: 1px solid var(--border-color);
  max-width: 80%;
}

.message.user .message-content {
  background: var(--accent-color);
  color: white;
  border-color: var(--accent-color);
}

.input-container {
  position: sticky;
  bottom: 0;
  background: var(--bg-primary);
  padding: 1rem 0;
  transition: transform 0.3s ease;
}

.model-selector {
  position: relative;
  max-width: 400px;
  margin-bottom: 1rem;
}

.selected-model {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 0.75rem 1rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all 0.3s ease;
}

.selected-model:hover {
  border-color: var(--accent-color);
}

.model-info {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.model-company {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
}

.model-name {
  font-size: 0.875rem;
  color: var(--text-primary);
  font-weight: 600;
}

.model-dropdown {
  position: absolute;
  bottom: 100%;
  left: 0;
  right: 0;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  margin-bottom: 0.25rem;
  box-shadow: var(--shadow-lg);
  z-index: 200;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px) scale(0.95);
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  max-height: 0;
  overflow: hidden;
  transform-origin: bottom center;
}

.model-dropdown.active {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
  max-height: 300px;
}

.model-search {
  position: relative;
  padding: 0.75rem;
  border-bottom: 1px solid var(--border-color);
}

.model-search input {
  width: 100%;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 0.375rem;
  padding: 0.5rem 2.5rem 0.5rem 0.75rem;
  color: var(--text-primary);
  font-size: 0.875rem;
  outline: none;
}

.model-search i {
  position: absolute;
  right: 1.5rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
}

.model-list {
  max-height: 200px;
  overflow-y: auto;
}

.model-item {
  padding: 0.75rem;
  cursor: pointer;
  border-bottom: 1px solid var(--border-color);
  transition: background-color 0.2s ease;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.model-item:hover {
  background: var(--bg-tertiary);
}

.model-item.selected {
  background: var(--accent-color);
  color: white;
}

.model-badge {
  background: var(--success-color);
  color: white;
  font-size: 0.625rem;
  padding: 0.25rem 0.5rem;
  border-radius: 1rem;
  font-weight: 600;
}

.input-box {
  background: var(--bg-secondary);
  border: 2px solid var(--border-color);
  border-radius: 1rem;
  padding: 1rem;
  display: flex;
  align-items: flex-end;
  gap: 0.75rem;
  transition: all 0.3s ease;
}

.input-box:hover {
  border-color: var(--accent-hover);
  transform: translateY(-2px);
}

.input-box:focus-within {
  border-color: var(--accent-color);
  transform: translateY(-2px);
}

#messageInput {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  color: var(--text-primary);
  font-size: 1rem;
  line-height: 1.5;
  resize: none;
  min-height: 1.5rem;
  max-height: 8rem;
  font-family: inherit;
}

.send-btn {
  background: var(--accent-color);
  border: none;
  border-radius: 0.5rem;
  color: white;
  padding: 0.75rem;
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 2.5rem;
  height: 2.5rem;
}

.send-btn:hover:not(:disabled) {
  background: var(--accent-hover);
  transform: scale(1.05);
}

.send-btn:disabled {
  background: var(--text-muted);
  cursor: not-allowed;
  opacity: 0.5;
}

.loading-indicator {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  padding: 2rem;
  display: none;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  z-index: 1000;
}

.loading-indicator.active {
  display: flex;
}

.loading-spinner {
  width: 2rem;
  height: 2rem;
  border: 3px solid var(--border-color);
  border-top: 3px solid var(--accent-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.error-toast {
  position: fixed;
  top: 2rem;
  right: 2rem;
  background: var(--error-color);
  color: white;
  padding: 1rem 1.5rem;
  border-radius: 0.5rem;
  display: none;
  align-items: center;
  gap: 0.75rem;
  z-index: 1000;
  max-width: 400px;
}

.error-toast.active {
  display: flex;
}

.error-close {
  background: none;
  border: none;
  color: white;
  cursor: pointer;
  padding: 0.25rem;
  border-radius: 0.25rem;
}

.theme-wave {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--bg-primary);
  z-index: 9999;
  pointer-events: none;
  opacity: 0;
  clip-path: circle(0% at 50% 100%);
  transition: clip-path 1.2s ease-in-out;
}

.theme-wave.active {
  opacity: 1;
  clip-path: circle(150% at 50% 100%);
}

@media (max-width: 768px) {
  .header {
    padding: 1rem;
  }
  
  .main-content {
    padding: 1rem;
  }
  
  .welcome-text {
    font-size: 2rem;
  }
  
  .message-content {
    max-width: 90%;
  }
}