:root {
  /* 现代AI助手风格配色 */
  --primary-color: #007AFF;
  --primary-dark: #0056CC;
  --primary-light: #4DA3FF;
  --secondary-color: #F2F2F7;
  --background-color: #FFFFFF;
  --surface-color: #FFFFFF;
  --text-primary: #000000;
  --text-secondary: #8E8E93;
  --text-hint: #C7C7CC;
  --border-color: #E5E5EA;
  --divider-color: #F2F2F7;
  --success-color: #34C759;
  --error-color: #FF3B30;
  --warning-color: #FF9500;
  --info-color: #007AFF;

  /* AI助手特色配色 */
  --ai-bubble-bg: #F2F2F7;
  --user-bubble-bg: #007AFF;
  --ai-text-color: #000000;
  --user-text-color: #FFFFFF;
  --chat-background: #FFFFFF;
  --input-background: #F2F2F7;
  
  /* 阴影效果 */
  --shadow-1: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
  --shadow-2: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);
  --shadow-3: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
  
  /* 圆角 */
  --border-radius-sm: 4px;
  --border-radius-md: 8px;
  --border-radius-lg: 12px;
  --border-radius-xl: 16px;
  
  /* 间距 */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  
  /* 字体 */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', 'Noto Color Emoji';
  --font-size-xs: 12px;
  --font-size-sm: 14px;
  --font-size-md: 16px;
  --font-size-lg: 18px;
  --font-size-xl: 20px;
  --font-size-xxl: 24px;
}

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

body {
  font-family: var(--font-family);
  font-size: var(--font-size-md);
  line-height: 1.5;
  color: var(--text-primary);
  background-color: var(--background-color);
  height: 100vh;
  overflow: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.app-container {
  height: 100vh;
  max-width: 100%;
  margin: 0 auto;
  position: relative;
}

/* 页面切换动画 */
.page {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  transform: translateX(100%);
  transition: all 0.3s ease-in-out;
  background-color: var(--background-color);
}

.page.active {
  opacity: 1;
  transform: translateX(0);
}

/* 登录页面 - 豆包风格 */
.login-container {
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: var(--spacing-xl);
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.login-card {
  background: var(--surface-color);
  border-radius: var(--border-radius-xl);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-3);
  width: 100%;
  max-width: 360px;
  text-align: center;
}

.login-logo {
  width: 80px;
  height: 80px;
  margin-bottom: var(--spacing-lg);
  border-radius: 50%;
  box-shadow: var(--shadow-2);
}

.login-title {
  font-size: var(--font-size-xxl);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
}

.login-subtitle {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xl);
}

.form-group {
  margin-bottom: var(--spacing-lg);
  text-align: left;
}

.form-label {
  display: block;
  margin-bottom: var(--spacing-sm);
  font-weight: 600;
  color: var(--text-primary);
  font-size: var(--font-size-sm);
}

.form-control {
  width: 100%;
  padding: var(--spacing-md);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  font-size: var(--font-size-md);
  transition: all 0.3s ease;
  background-color: var(--surface-color);
}

.form-control:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(30, 136, 229, 0.1);
}

.btn {
  padding: var(--spacing-md) var(--spacing-lg);
  border: none;
  border-radius: var(--border-radius-md);
  cursor: pointer;
  font-size: var(--font-size-md);
  font-weight: 600;
  transition: all 0.3s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  text-decoration: none;
  min-height: 44px;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
  color: white;
  box-shadow: var(--shadow-1);
}

.btn-primary:hover {
  box-shadow: var(--shadow-2);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0);
  box-shadow: var(--shadow-1);
}

.btn-secondary {
  background-color: var(--surface-color);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

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

.btn-small {
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: var(--font-size-sm);
  min-height: 36px;
}

.status-message {
  margin-top: var(--spacing-md);
  padding: var(--spacing-md);
  border-radius: var(--border-radius-md);
  font-size: var(--font-size-sm);
  font-weight: 500;
}

.status-message.error {
  background-color: rgba(244, 67, 54, 0.1);
  color: var(--error-color);
}

.status-message.success {
  background-color: rgba(76, 175, 80, 0.1);
  color: var(--success-color);
}

/* 主页面 - 豆包风格 */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-md) var(--spacing-lg);
  background-color: var(--surface-color);
  box-shadow: var(--shadow-1);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-title {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--text-primary);
}

.user-info {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.user-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background-color: var(--primary-color);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: var(--font-size-sm);
}

/* 移动端底部导航 */
.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background-color: var(--surface-color);
  box-shadow: 0 -2px 10px rgba(0,0,0,0.1);
  display: none;
  z-index: 1000;
}

.bottom-nav-items {
  display: flex;
  justify-content: space-around;
  padding: var(--spacing-sm) 0;
}

.bottom-nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-sm);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: var(--font-size-xs);
  transition: color 0.3s ease;
}

.bottom-nav-item.active {
  color: var(--primary-color);
}

.bottom-nav-icon {
  font-size: var(--font-size-lg);
}

/* 主内容区域 */
.main-content {
  display: flex;
  height: calc(100vh - 64px);
  position: relative;
}

/* 会话面板 - 豆包风格 */
.sessions-panel {
  width: 100%;
  max-width: 400px;
  background-color: var(--surface-color);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.panel-header {
  padding: var(--spacing-lg);
  border-bottom: 1px solid var(--divider-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: linear-gradient(135deg, var(--surface-color) 0%, var(--secondary-color) 100%);
}

.panel-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
  font-family: 'Inter', sans-serif;
}

.sessions-list {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-md);
  background-color: var(--background-color);
}

.session-item {
  display: flex;
  align-items: center;
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-sm);
  border-radius: var(--border-radius-lg);
  cursor: pointer;
  transition: all 0.2s ease;
  background-color: var(--surface-color);
  border: 1px solid transparent;
  box-shadow: var(--shadow-1);
  position: relative;
  overflow: hidden;
}

.session-item::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 100%;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  opacity: 0;
  transition: opacity 0.2s ease;
}

.session-item:hover {
  background-color: var(--surface-color);
  transform: translateY(-2px);
  box-shadow: var(--shadow-2);
}

.session-item:hover::before {
  opacity: 1;
}

.session-item.active {
  background-color: rgba(30, 136, 229, 0.05);
  border-color: var(--primary-color);
  box-shadow: var(--shadow-2);
}

.session-item.active::before {
  opacity: 1;
}

.session-avatar {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  margin-right: var(--spacing-md);
  flex-shrink: 0;
  box-shadow: var(--shadow-1);
  transition: transform 0.2s ease;
}

.session-item:hover .session-avatar {
  transform: scale(1.05);
}

.session-content {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.session-title {
  font-weight: 600;
  color: var(--text-primary);
  font-size: var(--font-size-md);
  line-height: 1.3;
  font-family: 'Inter', sans-serif;
}

.session-preview {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  line-height: 1.4;
}

.session-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: var(--spacing-xs);
}

.session-time {
  font-size: var(--font-size-xs);
  color: var(--text-hint);
  font-weight: 500;
}

.session-badge {
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  color: white;
  border-radius: 12px;
  padding: 2px 8px;
  font-size: var(--font-size-xs);
  font-weight: 600;
  min-width: 18px;
  text-align: center;
  box-shadow: var(--shadow-1);
}

/* 滚动条样式 */
.sessions-list::-webkit-scrollbar {
  width: 4px;
}

.sessions-list::-webkit-scrollbar-track {
  background: transparent;
}

.sessions-list::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 2px;
}

.sessions-list::-webkit-scrollbar-thumb:hover {
  background: var(--text-hint);
}

/* 聊天面板 - 豆包风格 */
.chat-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  background-color: var(--background-color);
  height: 100%;
}

.chat-header {
  padding: var(--spacing-lg);
  border-bottom: 1px solid var(--divider-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: var(--surface-color);
  box-shadow: var(--shadow-1);
}

.chat-header-left {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.chat-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  box-shadow: var(--shadow-1);
}

.chat-title {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--text-primary);
  font-family: 'Inter', sans-serif;
}

.chat-subtitle {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  margin-top: 2px;
}

.chat-actions {
  display: flex;
  gap: var(--spacing-sm);
}

.no-session-message {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 100%;
  color: var(--text-secondary);
  text-align: center;
  padding: var(--spacing-xl);
  background: linear-gradient(135deg, var(--surface-color) 0%, var(--secondary-color) 100%);
}

.no-session-icon {
  font-size: 72px;
  margin-bottom: var(--spacing-lg);
  opacity: 0.3;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.no-session-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.no-session-subtitle {
  font-size: var(--font-size-md);
  color: var(--text-secondary);
  opacity: 0.8;
}

.chat-container {
  display: flex;
  flex-direction: column;
  height: 100%;
  background-color: var(--chat-background);
  position: relative;
}

.chat-container.hidden {
  display: none;
}

.messages-container {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-lg) var(--spacing-md);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  background-color: var(--chat-background);
  scroll-behavior: smooth;
}

.message {
  display: flex;
  max-width: 80%;
  gap: var(--spacing-xs);
  animation: messageSlideIn 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  position: relative;
  margin-bottom: var(--spacing-xs);
}

@keyframes messageSlideIn {
  from {
    opacity: 0;
    transform: translateY(20px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@keyframes typingDots {
  0%, 60%, 100% {
    transform: translateY(0);
  }
  30% {
    transform: translateY(-10px);
  }
}

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

.message.assistant {
  align-self: flex-start;
}

.message-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 12px;
  color: white;
  transition: all 0.2s ease;
  margin-top: 4px;
}

.message.user .message-avatar {
  background: var(--user-bubble-bg);
  box-shadow: 0 2px 8px rgba(0, 122, 255, 0.3);
}

.message.assistant .message-avatar {
  background: linear-gradient(135deg, #FF6B6B, #4ECDC4);
  box-shadow: 0 2px 8px rgba(255, 107, 107, 0.3);
}

.message-content {
  border-radius: 18px;
  padding: 12px 16px;
  max-width: 100%;
  word-wrap: break-word;
  position: relative;
  font-size: 16px;
  line-height: 1.4;
  transition: all 0.2s ease;
}

.message.user .message-content {
  background: var(--user-bubble-bg);
  color: var(--user-text-color);
  border-bottom-right-radius: 6px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
}

.message.assistant .message-content {
  background: var(--ai-bubble-bg);
  color: var(--ai-text-color);
  border-bottom-left-radius: 6px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

.message-text {
  font-size: 16px;
  line-height: 1.4;
  word-wrap: break-word;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  margin: 0;
}

.message-time {
  font-size: 11px;
  color: var(--text-hint);
  margin-top: 4px;
  opacity: 0.6;
  text-align: right;
  font-weight: 400;
}

.message.user .message-time {
  color: rgba(255, 255, 255, 0.7);
  text-align: left;
}

.message.assistant .message-time {
  color: var(--text-secondary);
}

/* 打字动画效果 */
.typing-indicator {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 12px 16px;
  background: var(--ai-bubble-bg);
  border-radius: 18px;
  border-bottom-left-radius: 6px;
  margin-bottom: var(--spacing-xs);
}

.typing-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--text-secondary);
  animation: typingDots 1.4s infinite ease-in-out;
}

.typing-dot:nth-child(2) {
  animation-delay: 0.2s;
}

.typing-dot:nth-child(3) {
  animation-delay: 0.4s;
}

/* 现代化输入区域 */
.message-input-container {
  display: flex;
  align-items: flex-end;
  padding: 12px 16px 20px 16px;
  background-color: var(--surface-color);
  gap: 8px;
  border-top: 1px solid var(--border-color);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  position: relative;
  z-index: 10;
  margin-bottom: 56px; /* 为底部导航留出空间 */
}

.message-input-wrapper {
  flex: 1;
  position: relative;
  background: var(--input-background);
  border-radius: 20px;
  padding: 2px;
}

.message-input {
  width: 100%;
  padding: 12px 16px;
  border: none;
  border-radius: 18px;
  font-size: 16px;
  resize: none;
  min-height: 20px;
  max-height: 100px;
  background-color: transparent;
  transition: all 0.2s ease;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.4;
  color: var(--text-primary);
}

.message-input:focus {
  outline: none;
  background-color: var(--surface-color);
}

.message-input::placeholder {
  color: var(--text-secondary);
  opacity: 0.8;
}

.input-actions {
  display: flex;
  gap: 8px;
  align-items: flex-end;
}

.input-action {
  width: 36px;
  height: 36px;
  border: none;
  border-radius: 50%;
  background: var(--primary-color);
  color: white;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
  box-shadow: 0 2px 8px rgba(0, 122, 255, 0.3);
  font-size: 18px;
  flex-shrink: 0;
}

.input-action:hover {
  background: var(--primary-dark);
  transform: scale(1.05);
  box-shadow: 0 4px 12px rgba(0, 122, 255, 0.4);
}

.input-action:active {
  transform: scale(0.95);
  box-shadow: 0 1px 4px rgba(0, 122, 255, 0.3);
}

.input-action:disabled {
  background: var(--text-hint);
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
  opacity: 0.4;
}

/* 搜索功能样式 */
.search-container {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-color);
}

.search-input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
  background: var(--input-background);
  border-radius: 12px;
  padding: 8px 12px;
  transition: all 0.2s ease;
}

.search-input-wrapper:focus-within {
  background: var(--surface-color);
  box-shadow: 0 0 0 2px rgba(0, 122, 255, 0.2);
}

.search-icon {
  color: var(--text-secondary);
  font-size: 20px;
  margin-right: 8px;
}

.search-input {
  flex: 1;
  border: none;
  background: transparent;
  font-size: 14px;
  color: var(--text-primary);
  outline: none;
  padding: 0;
}

.search-input::placeholder {
  color: var(--text-secondary);
}

.clear-search-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 4px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
}

.clear-search-btn:hover {
  background: var(--border-color);
  color: var(--text-primary);
}

.clear-search-btn .material-icons {
  font-size: 18px;
}

/* 会话操作按钮 */
.session-actions {
  display: flex;
  gap: 4px;
  opacity: 0;
  transition: opacity 0.2s ease;
}

.session-item:hover .session-actions {
  opacity: 1;
}

.session-action-btn {
  width: 28px;
  height: 28px;
  border: none;
  border-radius: 50%;
  background: var(--border-color);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
  flex-shrink: 0;
}

.session-action-btn:hover {
  background: var(--primary-color);
  color: white;
  transform: scale(1.1);
}

.session-action-btn[data-action="delete"]:hover {
  background: var(--error-color);
}

.session-action-btn .material-icons {
  font-size: 16px;
}

/* 工具调用样式 */
.tool-call {
  background-color: var(--secondary-color);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-md);
  margin: var(--spacing-sm) 0;
  border-left: 4px solid var(--primary-color);
}

.tool-call-header {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
  font-size: var(--font-size-sm);
}

.tool-call-content {
  font-family: 'SF Mono', Monaco, Inconsolata, 'Roboto Mono', 'Courier New', monospace;
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  overflow-x: auto;
}

/* 加载状态 */
.loading {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: var(--spacing-xl);
  color: var(--text-secondary);
}

.loading-spinner {
  width: 24px;
  height: 24px;
  border: 2px solid var(--border-color);
  border-top: 2px solid var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* 空状态 */
.empty-state {
  text-align: center;
  padding: var(--spacing-xl);
  color: var(--text-secondary);
}

.empty-state-icon {
  font-size: 48px;
  margin-bottom: var(--spacing-md);
  opacity: 0.5;
}

.empty-state-title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
}

.empty-state-subtitle {
  font-size: var(--font-size-sm);
  color: var(--text-hint);
}

/* 响应式设计 */
@media (max-width: 768px) {
  .main-content {
    flex-direction: column;
  }

  .sessions-panel {
    width: 100%;
    max-width: 100%;
    height: 100%;
    border-right: none;
    border-bottom: none;
  }

  .chat-panel {
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--surface-color);
    transform: translateX(100%);
    transition: transform 0.3s ease-in-out;
    z-index: 200;
  }

  .chat-panel.active {
    transform: translateX(0);
  }

  .bottom-nav {
    display: block;
  }

  .main-content {
    height: calc(100vh - 64px - 56px);
  }

  .message {
    max-width: 90%;
  }

  .message-avatar {
    width: 28px;
    height: 28px;
  }

  .message-content {
    padding: var(--spacing-sm) var(--spacing-md);
  }
}

@media (max-width: 480px) {
  .login-card {
    margin: var(--spacing-md);
    padding: var(--spacing-lg);
  }

  .sessions-panel,
  .chat-panel {
    padding: var(--spacing-sm);
  }

  .messages-container {
    padding: var(--spacing-md);
  }

  .message-input-container {
    padding: var(--spacing-sm);
  }
}

/* PWA独立模式适配 */
@media (display-mode: standalone) {
  body {
    padding-top: env(safe-area-inset-top);
    padding-bottom: env(safe-area-inset-bottom);
  }

  .app-container {
    height: 100vh;
    height: calc(100vh - env(safe-area-inset-top) - env(safe-area-inset-bottom));
  }

  .chat-container {
    height: calc(100vh - 120px); /* 减去头部和底部导航的高度 */
  }

  .messages-container {
    padding-bottom: 20px; /* 额外的底部间距 */
  }

  .message-input-container {
    padding-bottom: calc(20px + env(safe-area-inset-bottom));
  }
}

/* 移动端PWA优化 */
@media (max-width: 768px) and (display-mode: standalone) {
  .chat-container {
    height: calc(100vh - 64px - 56px - env(safe-area-inset-top) - env(safe-area-inset-bottom));
  }

  .bottom-nav {
    padding-bottom: env(safe-area-inset-bottom);
  }
}

/* 深色模式支持 */
@media (prefers-color-scheme: dark) {
  :root {
    --background-color: #121212;
    --surface-color: #1e1e1e;
    --text-primary: #ffffff;
    --text-secondary: #b3b3b3;
    --text-hint: #666666;
    --border-color: #333333;
    --divider-color: #262626;
    --secondary-color: #2a2a2a;
  }
}

/* 优化移动端响应式布局 */
@media (max-width: 768px) {
  .main-content {
    flex-direction: column;
  }

  .sessions-panel {
    width: 100%;
    max-width: 100%;
    height: 100%;
    border-right: none;
    border-bottom: none;
  }

  .chat-panel {
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--background-color);
    transform: translateX(100%);
    transition: transform 0.3s ease-in-out;
    z-index: 200;
  }

  .chat-panel.active {
    transform: translateX(0);
  }

  .bottom-nav {
    display: block;
  }

  .main-content {
    height: calc(100vh - 64px - 56px);
  }

  .chat-container {
    height: calc(100vh - 64px - 56px);
    padding-bottom: 0;
  }

  .messages-container {
    height: calc(100vh - 64px - 56px - 80px); /* 减去输入框高度 */
    padding-bottom: 20px;
  }

  .message {
    max-width: 90%;
  }

  .message-avatar {
    width: 32px;
    height: 32px;
  }

  .message-content {
    padding: var(--spacing-sm) var(--spacing-md);
  }

  .sessions-list {
    padding: var(--spacing-sm);
  }

  .session-item {
    padding: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
  }

  .session-avatar {
    width: 44px;
    height: 44px;
  }

  .panel-header {
    padding: var(--spacing-md);
  }

  .panel-title {
    font-size: var(--font-size-lg);
  }

  .chat-header {
    padding: var(--spacing-md);
  }

  .messages-container {
    padding: var(--spacing-md);
  }

  .message-input-container {
    padding: var(--spacing-sm);
  }

  .message-input {
    min-height: 44px;
    font-size: var(--font-size-sm);
  }

  .input-action {
    width: 44px;
    height: 44px;
  }
}

@media (max-width: 480px) {
  .login-card {
    margin: var(--spacing-md);
    padding: var(--spacing-lg);
  }

  .sessions-panel,
  .chat-panel {
    padding: var(--spacing-sm);
  }

  .messages-container {
    padding: var(--spacing-sm);
  }

  .message-input-container {
    padding: var(--spacing-sm);
  }

  .message {
    max-width: 95%;
  }

  .message-content {
    padding: var(--spacing-sm) var(--spacing-md);
  }

  .chat-avatar {
    width: 40px;
    height: 40px;
  }

  .session-avatar {
    width: 40px;
    height: 40px;
  }
}

/* 添加现代动画和过渡效果 */
@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.7;
  }
}

.loading-spinner {
  animation: spin 1s linear infinite;
}

.loading {
  animation: pulse 1.5s ease-in-out infinite;
}

/* 提升工具调用样式 */
.tool-call {
  background: linear-gradient(135deg, var(--secondary-color), rgba(30, 136, 229, 0.05));
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-md);
  margin: var(--spacing-sm) 0;
  border-left: 4px solid var(--primary-color);
  box-shadow: var(--shadow-1);
  transition: all 0.2s ease;
}

.tool-call:hover {
  transform: translateX(2px);
  box-shadow: var(--shadow-2);
}

.tool-call-header {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
  font-size: var(--font-size-sm);
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.tool-call-content {
  font-family: 'SF Mono', Monaco, Inconsolata, 'Roboto Mono', 'Courier New', monospace;
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  overflow-x: auto;
  background: var(--surface-color);
  padding: var(--spacing-sm);
  border-radius: var(--border-radius-md);
  border: 1px solid var(--border-color);
}

/* 空状态优化 */
.empty-state {
  text-align: center;
  padding: var(--spacing-xl);
  color: var(--text-secondary);
  animation: slideUp 0.5s ease-out;
}

.empty-state-icon {
  font-size: 64px;
  margin-bottom: var(--spacing-lg);
  opacity: 0.3;
  transition: transform 0.3s ease;
}

.empty-state:hover .empty-state-icon {
  transform: scale(1.1);
}

.empty-state-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.empty-state-subtitle {
  font-size: var(--font-size-md);
  color: var(--text-secondary);
  opacity: 0.8;
  line-height: 1.5;
}

/* 按钮样式优化 */
.btn {
  padding: var(--spacing-md) var(--spacing-lg);
  border: none;
  border-radius: var(--border-radius-lg);
  cursor: pointer;
  font-size: var(--font-size-md);
  font-weight: 600;
  transition: all 0.3s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  text-decoration: none;
  min-height: 44px;
  font-family: 'Inter', sans-serif;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
  transition: left 0.5s ease;
}

.btn:hover::before {
  left: 100%;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
  color: white;
  box-shadow: var(--shadow-2);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-3);
}

.btn-primary:active {
  transform: translateY(0);
  box-shadow: var(--shadow-1);
}

.btn-secondary {
  background-color: var(--surface-color);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-1);
}

.btn-secondary:hover {
  background-color: var(--secondary-color);
  transform: translateY(-1px);
  box-shadow: var(--shadow-2);
}

.btn-small {
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: var(--font-size-sm);
  min-height: 36px;
}

.hidden {
  display: none !important;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}