/* ========== Reset & Variables ========== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --bg-page: #F8FBFF;
  --bg-content: #FFFFFF;
  --bg-sidebar: transparent;
  --bg-card: #F5F7FA;
  --bg-input: #F4F6FA;
  --text-primary: #2A2F45;
  --text-secondary: #636877;
  --text-tertiary: #9499A8;
  --text-placeholder: #B8BCC8;
  --border-color: #EBEDF0;
  --accent: #3674FC;
  --accent-light: #E8F0FE;
  --accent-gradient: linear-gradient(135deg, #3674FC, #5B8DFF);
  --menu-active-bg: #EDF1FE;
  --menu-active-text: #3674FC;
  --shadow-sm: 0 1px 3px rgba(0,0,0,.04);
  --shadow-md: 0 4px 20px rgba(0,0,0,.06);
  --shadow-lg: 0 8px 40px rgba(0,0,0,.08);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --header-h: 54px;
  --banner-h: 48px;
  --sidebar-w: 200px;
  --font-display: "PingFang SC", "Microsoft YaHei", "Segoe UI", system-ui, sans-serif;
}

html, body {
  height: 100%;
  font-family: var(--font-display);
  background: var(--bg-page);
  color: var(--text-primary);
  -webkit-font-smoothing: antialiased;
}

/* ========== Top Banner ========== */
.top-banner {
  height: var(--banner-h);
  background: linear-gradient(135deg, #1a1a2e 0%, #16213e 40%, #0f3460 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}
.top-banner::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 30% 50%, rgba(54,116,252,0.15) 0%, transparent 70%),
              radial-gradient(ellipse at 70% 50%, rgba(91,141,255,0.1) 0%, transparent 70%);
}
.top-banner-inner {
  position: relative;
  display: flex;
  align-items: center;
  gap: 10px;
  z-index: 1;
}
.top-banner .vip-icon {
  width: 28px; height: 28px;
  background: linear-gradient(135deg, #FFD700, #FFA500);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  color: #fff;
}
.top-banner .vip-icon svg { width: 14px; height: 14px; }
.top-banner .vip-text {
  color: #fff;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.5px;
}
.top-banner .vip-link {
  color: #FFD700;
  font-size: 13px;
  text-decoration: none;
  margin-left: 4px;
  font-weight: 600;
  transition: opacity 0.2s;
}
.top-banner .vip-link:hover { opacity: 0.8; }
.top-banner .close-btn {
  position: absolute;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  width: 20px; height: 20px;
  cursor: pointer;
  z-index: 2;
  opacity: 0.6;
  transition: opacity 0.2s;
}
.top-banner .close-btn:hover { opacity: 1; }
.top-banner .close-btn::before,
.top-banner .close-btn::after {
  content: '';
  position: absolute;
  width: 14px; height: 1.5px;
  background: #fff;
  top: 50%; left: 50%;
}
.top-banner .close-btn::before { transform: translate(-50%,-50%) rotate(45deg); }
.top-banner .close-btn::after { transform: translate(-50%,-50%) rotate(-45deg); }
/* ========== Header ========== */
.header {
  height: var(--header-h);
  background: var(--bg-page);
  display: flex;
  align-items: center;
  padding: 0 28px;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-logo {
  display: block;
  width: 116px; height: 54px;
  flex-shrink: 0;
  background: url(../fonts/317e92f7b21b4b679189d6ba8ec9850e.woff);
  font-weight: 500;
}
.header-action.vip-action:hover { background: var(--accent-light); }
.header-action.login-action {
  color: var(--text-secondary);
}
.header-divider {
  width: 1px; height: 16px;
  background: var(--border-color);
  margin: 0 4px;
}

/* ========== Main Layout ========== */
.main-container,
.main-layout {
  display: flex;
  height: calc(100vh - var(--header-h) - var(--banner-h));
}

/* ========== Sidebar ========== */
.sidebar {
  width: var(--sidebar-w);
  display: flex;
  flex-direction: column;
  background: transparent;
  flex-shrink: 0;
  padding: 12px 8px;
}
.sidebar-menus {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2px;
  overflow-y: auto;
}
.sidebar-menu {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s;
  height: 36px;
  border: none;
  background: transparent;
  font-family: inherit;
  text-align: left;
  width: 100%;
  position: relative;
}
.sidebar-menu:hover { background: rgba(0,0,0,0.03); color: var(--text-primary); }
.sidebar-menu.active {
  background: var(--menu-active-bg);
  color: var(--menu-active-text);
  font-weight: 500;
}
.sidebar-menu .menu-icon {
  width: 20px; height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  opacity: 0.65;
  color: var(--text-secondary);
  transition: all 0.15s;
}
.sidebar-menu .menu-icon svg { width: 20px; height: 20px; }
.sidebar-menu.active .menu-icon { opacity: 1; color: var(--menu-active-text); }
.sidebar-menu:hover .menu-icon { opacity: 0.85; }
.sidebar-menu .menu-badge {
  margin-left: 4px;
  font-size: 10px;
  background: #E54D42;
  color: #fff;
  padding: 2px 8px;
  border-radius: 10px;
  font-weight: 500;
  letter-spacing: 0.2px;
  line-height: 16px;
  white-space: nowrap;
}
.sidebar-menu .menu-badge.new-badge {
  background: #E54D42;
  color: #fff;
}
.sidebar-footer {
  padding: 12px 4px 8px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  border-top: 1px solid var(--border-color);
  margin-top: auto;
}
.sidebar-footer-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  color: var(--text-tertiary);
  cursor: pointer;
  border: none;
  background: transparent;
  font-family: inherit;
  transition: all 0.15s;
}
.sidebar-footer-btn:hover { color: var(--text-secondary); background: rgba(0,0,0,0.03); }
.sidebar-footer-btn .ft-icon {
  width: 16px; height: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0.6;
  transition: transform 0.3s;
}
.sidebar-footer-btn .ft-icon svg { width: 16px; height: 16px; }

/* Sidebar collapsed state */
.sidebar.collapsed {
  width: 56px;
  padding: 12px 4px;
}
.sidebar.collapsed .sidebar-menu {
  justify-content: center;
  padding: 8px 4px;
  gap: 0;
}
.sidebar.collapsed .sidebar-menu .menu-text,
.sidebar.collapsed .sidebar-menu .menu-badge,
.sidebar.collapsed .sidebar-footer-btn .ft-text {
  display: none;
}
.sidebar.collapsed .sidebar-footer-btn {
  justify-content: center;
  padding: 8px;
}
.sidebar.collapsed .sidebar-footer {
  align-items: center;
}

/* ========== Content Area ========== */
.content {
  flex: 1;
  display: flex;
  flex-direction: column;
  background: var(--bg-content);
  border-radius: var(--radius-lg) 0 0 0;
  box-shadow: var(--shadow-sm);
  min-width: 0;
  overflow: hidden;
}

/* Tabs */
.content-tabs {
  display: flex;
  align-items: center;
  gap: 0;
  padding: 0 28px;
  height: 44px;
  border-bottom: 1px solid var(--border-color);
  flex-shrink: 0;
}
.content-tab {
  padding: 10px 16px;
  font-size: 15px;
  color: var(--text-secondary);
  cursor: pointer;
  border: none;
  background: none;
  font-family: inherit;
  position: relative;
  transition: color 0.2s;
  white-space: nowrap;
}
.content-tab:hover { color: var(--text-primary); }
.content-tab.active {
  color: var(--text-primary);
  font-weight: 600;
}
.content-tab.active::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 50%;
  transform: translateX(-50%);
  width: 24px; height: 3px;
  background: var(--accent);
  border-radius: 2px 2px 0 0;
}

/* Main content body */
.content-body {
  flex: 1;
  display: flex;
  overflow: hidden;
}

/* Center panel */
.center-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  padding: 40px 48px 20px;
  min-width: 0;
}

/* AI Greeting */
.ai-greeting {
  margin-bottom: 30px;
}
.ai-greeting .greeting-avatar {
  width: 56px; height: 56px;
  background: var(--accent-gradient);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  box-shadow: 0 4px 16px rgba(54,116,252,0.25);
}
.ai-greeting .greeting-avatar svg { width: 28px; height: 28px; color: #fff; }
.ai-greeting .greeting-title {
  font-size: 26px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
  letter-spacing: -0.3px;
}
.ai-greeting .greeting-subtitle {
  font-size: 14px;
  color: var(--text-tertiary);
  line-height: 1.6;
}

/* Demo cards */
.demo-cards {
  display: flex;
  gap: 14px;
  margin-bottom: 30px;
  flex-wrap: wrap;
}
.demo-card {
  flex: 1;
  min-width: 280px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px;
  cursor: pointer;
  transition: all 0.2s;
  position: relative;
  overflow: hidden;
}
.demo-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.demo-card .card-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 14px;
}
.demo-card .card-icon {
  width: 32px; height: 32px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
}
.demo-card .card-icon svg { width: 18px; height: 18px; }
.demo-card .card-icon.polish { background: #E8F5E9; color: #4CAF50; }
.demo-card .card-icon.grammar { background: #FFF3E0; color: #FF9800; }
.demo-card .card-icon.reading { background: #E3F2FD; color: #2196F3; }
.demo-card .card-label {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
}
.demo-card .card-source {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 10px;
  padding: 10px 12px;
  background: rgba(0,0,0,0.02);
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--border-color);
}
.demo-card .card-result {
  font-size: 13px;
  color: var(--accent);
  line-height: 1.7;
  padding: 10px 12px;
  background: var(--accent-light);
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--accent);
}

/* Input area */
.input-area {
  position: sticky;
  bottom: 0;
  background: var(--bg-content);
  padding: 16px 0;
  border-top: 1px solid var(--border-color);
}
.input-wrapper {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  background: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 10px 16px;
  transition: all 0.2s;
}
.input-wrapper:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(54,116,252,0.08);
}
.input-wrapper .lang-select {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  color: var(--text-secondary);
  cursor: pointer;
  border: none;
  background: rgba(0,0,0,0.03);
  font-family: inherit;
  white-space: nowrap;
  flex-shrink: 0;
  transition: background 0.15s;
}
.input-wrapper .lang-select:hover { background: rgba(0,0,0,0.06); }
.input-wrapper .input-field {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  font-size: 15px;
  font-family: inherit;
  color: var(--text-primary);
  resize: none;
  min-height: 24px;
  line-height: 1.6;
  padding: 2px 0;
}
.input-wrapper .input-field::placeholder { color: var(--text-placeholder); }
.input-toolbar {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-shrink: 0;
}
.input-toolbar .tool-btn {
  width: 30px; height: 30px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--text-tertiary);
  transition: all 0.15s;
  font-family: inherit;
}
.input-toolbar .tool-btn svg { width: 18px; height: 18px; }
.input-toolbar .tool-btn:hover { background: rgba(0,0,0,0.05); color: var(--text-secondary); }
.input-toolbar .lang-swap { font-weight: 600; }

/* Right AI panel */
.right-panel {
  width: 320px;
  border-left: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  background: var(--bg-page);
  flex-shrink: 0;
  padding: 20px 16px;
}

.right-panel .model-selector {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 16px;
  padding: 8px 12px;
  background: var(--bg-content);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  cursor: pointer;
  font-size: 13px;
  color: var(--text-primary);
  transition: all 0.15s;
}
.right-panel .model-selector:hover { border-color: var(--accent); }
.right-panel .model-icon {
  width: 24px; height: 24px;
  background: var(--accent-gradient);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  flex-shrink: 0;
}
.right-panel .model-icon svg { width: 14px; height: 14px; }
.right-panel .model-arrow {
  margin-left: auto;
  font-size: 12px;
  color: var(--text-tertiary);
}

.right-panel .ai-tools {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 20px;
}
.ai-tool-chip {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 12px;
  color: var(--text-secondary);
  background: var(--bg-content);
  border: 1px solid var(--border-color);
  cursor: pointer;
  transition: all 0.15s;
  font-family: inherit;
}
.ai-tool-chip:hover { border-color: var(--accent); color: var(--accent); }
.ai-tool-chip .chip-icon { display: flex; align-items: center; opacity: 0.7; }
.ai-tool-chip .chip-icon svg { width: 14px; height: 14px; }
.ai-tool-chip .chip-arrow { font-size: 10px; opacity: 0.5; margin-left: 2px; }

.right-panel .history-hint {
  margin-top: auto;
  text-align: center;
}
.right-panel .history-login {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 13px;
  color: var(--accent);
  cursor: pointer;
  border: 1px solid var(--accent);
  background: transparent;
  font-family: inherit;
  transition: all 0.2s;
  margin-bottom: 8px;
}
.right-panel .history-login:hover { background: var(--accent); color: #fff; }
.right-panel .history-text {
  font-size: 12px;
  color: var(--text-tertiary);
}

/* ========== 文档翻译页面 ========== */
.doc-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  padding: 40px 20px;
}
.doc-upload {
  width: 100%;
  max-width: 680px;
  border: 2px dashed var(--border-color);
  border-radius: var(--radius-lg);
  padding: 60px 40px;
  text-align: center;
  background: var(--bg-card);
  transition: all 0.2s;
  cursor: pointer;
  margin-bottom: 30px;
}
.doc-upload:hover {
  border-color: var(--accent);
  background: var(--accent-light);
}
.doc-upload .upload-icon {
  width: 64px; height: 64px;
  margin: 0 auto 20px;
  background: var(--accent-gradient);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}
.doc-upload .upload-icon svg { width: 28px; height: 28px; color: #fff; }
.doc-upload .upload-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}
.doc-upload .upload-hint {
  font-size: 13px;
  color: var(--text-tertiary);
  line-height: 1.6;
}
.doc-upload .upload-btn {
  display: inline-block;
  margin-top: 20px;
  padding: 10px 32px;
  background: var(--accent);
  color: #fff;
  border-radius: 20px;
  font-size: 14px;
  font-weight: 500;
  border: none;
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
}
.doc-upload .upload-btn:hover { opacity: 0.85; }

.doc-formats {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 30px;
}
.doc-format-tag {
  padding: 6px 14px;
  background: var(--bg-content);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  font-size: 12px;
  color: var(--text-secondary);
}
.doc-features {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
  justify-content: center;
  width: 100%;
  max-width: 680px;
}
.doc-feature {
  flex: 1;
  min-width: 180px;
  background: var(--bg-content);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px;
  text-align: center;
}
.doc-feature .feature-icon {
  width: 40px; height: 40px;
  margin: 0 auto 12px;
  background: var(--accent-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
}
.doc-feature .feature-icon svg { width: 20px; height: 20px; color: var(--accent); }
.doc-feature .feature-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
}
.doc-feature .feature-desc {
  font-size: 12px;
  color: var(--text-tertiary);
  line-height: 1.5;
}

/* ========== AI写作页面 ========== */
.write-page {
  display: flex;
  flex-direction: column;
  gap: 24px;
  max-width: 800px;
  margin: 0 auto;
  padding: 20px 0;
}
.write-header {
  margin-bottom: 8px;
}
.write-header h2 {
  font-size: 22px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}
.write-header p {
  font-size: 14px;
  color: var(--text-tertiary);
  line-height: 1.6;
}
.write-input-area {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
}
.write-topic-label {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 8px;
}
.write-topic-input {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: inherit;
  color: var(--text-primary);
  background: #fff;
  outline: none;
  transition: border-color 0.2s;
  box-sizing: border-box;
}
.write-topic-input:focus {
  border-color: var(--accent);
}
.write-topic-input::placeholder {
  color: var(--text-placeholder);
}
.write-options {
  display: flex;
  gap: 12px;
  margin-top: 16px;
  flex-wrap: wrap;
}
.write-option {
  padding: 8px 16px;
  border: 1px solid var(--border-color);
  border-radius: 20px;
  font-size: 13px;
  color: var(--text-secondary);
  background: #fff;
  cursor: pointer;
  transition: all 0.15s;
  font-family: inherit;
}
.write-option:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.write-option.active {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 500;
}
.write-generate-btn {
  display: block;
  width: 100%;
  padding: 12px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: opacity 0.2s;
  font-family: inherit;
  margin-top: 16px;
}
.write-generate-btn:hover { opacity: 0.85; }

.write-result {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  min-height: 200px;
}
.write-result .result-placeholder {
  text-align: center;
  color: var(--text-placeholder);
  font-size: 14px;
  padding: 60px 0;
}
.write-result .result-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}
.write-result .result-body {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.8;
}

/* ========== AI PPT页面 ========== */
.ppt-page {
  display: flex;
  flex-direction: column;
  gap: 24px;
  max-width: 800px;
  margin: 0 auto;
  padding: 20px 0;
}
.ppt-header {
  margin-bottom: 8px;
}
.ppt-header h2 {
  font-size: 22px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}
.ppt-header p {
  font-size: 14px;
  color: var(--text-tertiary);
  line-height: 1.6;
}
.ppt-input-area {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
}
.ppt-topic-label {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 8px;
}
.ppt-topic-input {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: inherit;
  color: var(--text-primary);
  background: #fff;
  outline: none;
  transition: border-color 0.2s;
  box-sizing: border-box;
}
.ppt-topic-input:focus {
  border-color: var(--accent);
}
.ppt-topic-input::placeholder {
  color: var(--text-placeholder);
}
.ppt-options {
  display: flex;
  gap: 12px;
  margin-top: 16px;
  flex-wrap: wrap;
}
.ppt-option {
  padding: 8px 16px;
  border: 1px solid var(--border-color);
  border-radius: 20px;
  font-size: 13px;
  color: var(--text-secondary);
  background: #fff;
  cursor: pointer;
  transition: all 0.15s;
  font-family: inherit;
}
.ppt-option:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.ppt-option.active {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 500;
}
.ppt-generate-btn {
  display: block;
  width: 100%;
  padding: 12px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: opacity 0.2s;
  font-family: inherit;
  margin-top: 16px;
}
.ppt-generate-btn:hover { opacity: 0.85; }

.ppt-preview {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  min-height: 200px;
}
.ppt-preview .preview-placeholder {
  text-align: center;
  color: var(--text-placeholder);
  font-size: 14px;
  padding: 60px 0;
}
.ppt-slides {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}
.ppt-slide {
  width: 180px;
  height: 120px;
  background: #fff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 16px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
}
.ppt-slide .slide-num {
  font-size: 11px;
  color: var(--text-tertiary);
  margin-bottom: 8px;
}
.ppt-slide .slide-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.4;
}

/* ========== Page Common ========== */
.page-header { padding: 32px 36px 20px; border-bottom: 1px solid var(--border-color); }
.page-header h1 { font-size: 24px; font-weight: 700; color: var(--text-primary); margin-bottom: 6px; }
.page-desc { font-size: 14px; color: var(--text-secondary); }

/* ========== 润色改写 & 降重降AI率页面 ========== */
.polish-container,
.reduce-container { padding: 36px; max-width: 800px; }
.result-text {
  padding: 20px; background: var(--bg-card); border-radius: var(--radius-md);
  font-size: 15px; line-height: 1.8; color: var(--text-primary); min-height: 120px;
}

/* ========== AI检测页面 ========== */
.check-container { padding: 36px; max-width: 800px; }
.input-section { margin-bottom: 20px; }
.input-section textarea {
  width: 100%; height: 200px; padding: 16px; border: 1px solid var(--border-color);
  border-radius: var(--radius-md); font-size: 15px; font-family: inherit; resize: vertical;
  transition: border-color 0.2s;
}
.input-section textarea:focus { outline: none; border-color: var(--accent); }
.input-actions { display: flex; justify-content: space-between; align-items: center; margin-top: 8px; }
.char-count { font-size: 13px; color: var(--text-tertiary); }
.btn-clear {
  padding: 6px 16px; border-radius: 20px; font-size: 13px; color: var(--text-secondary);
  background: var(--bg-card); border: 1px solid var(--border-color); cursor: pointer; font-family: inherit;
}
.btn-check {
  display: block; width: 100%; padding: 14px; border-radius: var(--radius-md);
  background: var(--accent-gradient); color: #fff; font-size: 16px; font-weight: 600;
  border: none; cursor: pointer; transition: opacity 0.2s; font-family: inherit;
}
.btn-check:hover { opacity: 0.9; }
.result-section { margin-top: 28px; padding: 28px; background: var(--bg-content); border-radius: var(--radius-lg); border: 1px solid var(--border-color); }
.result-header { margin-bottom: 20px; }
.result-header h3 { font-size: 18px; font-weight: 600; }
.result-score { display: flex; align-items: center; gap: 28px; margin-bottom: 24px; }
.score-circle {
  width: 100px; height: 100px; border-radius: 50%; background: var(--accent-light);
  display: flex; align-items: center; justify-content: center; gap: 2px; flex-shrink: 0;
}
.score-num { font-size: 36px; font-weight: 700; color: var(--accent); }
.score-unit { font-size: 16px; color: var(--accent); }
.score-label { font-size: 14px; color: var(--text-secondary); }
.result-details { display: flex; flex-direction: column; gap: 16px; }
.detail-item { display: flex; align-items: center; gap: 12px; }
.detail-label { font-size: 14px; color: var(--text-secondary); width: 100px; flex-shrink: 0; }
.detail-bar { flex: 1; height: 8px; background: var(--bg-card); border-radius: 4px; overflow: hidden; }
.bar-fill { height: 100%; background: var(--accent-gradient); border-radius: 4px; transition: width 0.6s ease; }

/* ========== 知识库页面 ========== */
.knowledge-container { padding: 36px; }
.kb-tabs { display: flex; gap: 8px; margin-bottom: 20px; }
.kb-tab {
  padding: 8px 20px; border-radius: 20px; font-size: 14px; color: var(--text-secondary);
  background: var(--bg-card); border: 1px solid transparent; cursor: pointer; font-family: inherit; transition: all 0.2s;
}
.kb-tab.active { background: var(--accent-light); color: var(--accent); border-color: var(--accent); }
.kb-actions { display: flex; gap: 10px; margin-bottom: 24px; }
.btn-new, .btn-import {
  padding: 8px 20px; border-radius: var(--radius-sm); font-size: 14px; cursor: pointer; font-family: inherit; transition: all 0.2s;
}
.btn-new { background: var(--accent); color: #fff; border: none; }
.btn-new:hover { opacity: 0.9; }
.btn-import { background: var(--bg-content); color: var(--text-primary); border: 1px solid var(--border-color); }
.kb-list { min-height: 300px; }
.kb-empty { display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 60px; color: var(--text-tertiary); gap: 12px; }

/* ========== 视频翻译页面 ========== */
.media-container { padding: 36px; }
.upload-area {
  border: 2px dashed var(--border-color); border-radius: var(--radius-lg); padding: 60px 40px;
  text-align: center; transition: all 0.2s; cursor: pointer; margin-bottom: 32px;
}
.upload-area:hover { border-color: var(--accent); background: var(--accent-light); }
.upload-title { font-size: 18px; font-weight: 600; margin: 16px 0 8px; color: var(--text-primary); }
.upload-hint { font-size: 14px; color: var(--text-tertiary); margin-bottom: 20px; }
.btn-upload {
  padding: 10px 32px; border-radius: var(--radius-md); background: var(--accent); color: #fff;
  border: none; font-size: 15px; cursor: pointer; font-family: inherit; transition: opacity 0.2s;
}
.btn-upload:hover { opacity: 0.9; }
.feature-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.feature-card { background: var(--bg-content); border-radius: var(--radius-md); padding: 28px 20px; text-align: center; border: 1px solid var(--border-color); transition: all 0.2s; }
.feature-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.feature-icon { font-size: 36px; margin-bottom: 12px; }
.feature-card h3 { font-size: 16px; font-weight: 600; margin-bottom: 8px; }
.feature-card p { font-size: 13px; color: var(--text-secondary); }

/* ========== Lobster页面 ========== */
.lobster-container { padding: 36px; max-width: 900px; margin: 0 auto; }
.lobster-chat { background: var(--bg-content); border-radius: var(--radius-lg); border: 1px solid var(--border-color); overflow: hidden; }
.chat-messages { padding: 24px; min-height: 400px; max-height: 500px; overflow-y: auto; }
.message { display: flex; gap: 12px; margin-bottom: 20px; }
.message.bot { flex-direction: row; }
.message-avatar { width: 36px; height: 36px; border-radius: 50%; background: var(--accent-light); display: flex; align-items: center; justify-content: center; font-size: 18px; flex-shrink: 0; }
.message-content { background: var(--bg-card); padding: 12px 16px; border-radius: var(--radius-md); font-size: 14px; line-height: 1.6; max-width: 80%; }
.chat-input { display: flex; gap: 10px; padding: 16px; border-top: 1px solid var(--border-color); }
.chat-input textarea { flex: 1; padding: 10px 14px; border: 1px solid var(--border-color); border-radius: var(--radius-md); font-size: 14px; font-family: inherit; resize: none; min-height: 44px; }
.chat-input textarea:focus { outline: none; border-color: var(--accent); }
.btn-send { padding: 10px 20px; border-radius: var(--radius-md); background: var(--accent); color: #fff; border: none; cursor: pointer; font-family: inherit; display: flex; align-items: center; }

/* ========== ArXiv论文页面 ========== */
.arxiv-container { padding: 36px; }
.search-box {
  display: flex; align-items: center; gap: 12px; padding: 12px 20px; background: var(--bg-content);
  border: 1px solid var(--border-color); border-radius: var(--radius-lg); margin-bottom: 20px;
}
.search-box svg { flex-shrink: 0; }
.search-box input { flex: 1; border: none; outline: none; font-size: 15px; font-family: inherit; background: transparent; }
.btn-search { padding: 8px 24px; border-radius: var(--radius-md); background: var(--accent); color: #fff; border: none; cursor: pointer; font-family: inherit; font-size: 14px; }
.arxiv-categories { display: flex; gap: 8px; margin-bottom: 24px; flex-wrap: wrap; }
.cat-btn {
  padding: 6px 16px; border-radius: 20px; font-size: 13px; color: var(--text-secondary);
  background: var(--bg-card); border: 1px solid transparent; cursor: pointer; font-family: inherit; transition: all 0.2s;
}
.cat-btn.active { background: var(--accent-light); color: var(--accent); border-color: var(--accent); }
.paper-list { display: flex; flex-direction: column; gap: 16px; }
.paper-item { background: var(--bg-content); border-radius: var(--radius-md); padding: 24px; border: 1px solid var(--border-color); transition: all 0.2s; }
.paper-item:hover { box-shadow: var(--shadow-md); }
.paper-title { font-size: 17px; font-weight: 600; color: var(--accent); margin-bottom: 8px; cursor: pointer; }
.paper-authors { font-size: 13px; color: var(--text-secondary); margin-bottom: 10px; }
.paper-abstract { font-size: 14px; color: var(--text-primary); line-height: 1.6; margin-bottom: 12px; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.paper-meta { display: flex; gap: 16px; font-size: 12px; color: var(--text-tertiary); }

/* ========== 网页翻译页面 ========== */
.web-translate-container { padding: 36px; max-width: 1000px; }
.url-input-section { margin-bottom: 28px; }
.url-input-wrapper {
  display: flex; align-items: center; gap: 12px; padding: 14px 20px; background: var(--bg-content);
  border: 1px solid var(--border-color); border-radius: var(--radius-lg);
}
.url-input-wrapper svg { flex-shrink: 0; }
.url-input-wrapper input { flex: 1; border: none; outline: none; font-size: 15px; font-family: inherit; background: transparent; }
.btn-translate-url { padding: 8px 24px; border-radius: var(--radius-md); background: var(--accent); color: #fff; border: none; cursor: pointer; font-family: inherit; font-size: 14px; white-space: nowrap; }
.browser-preview { background: var(--bg-content); border-radius: var(--radius-lg); border: 1px solid var(--border-color); overflow: hidden; }
.browser-toolbar { display: flex; align-items: center; gap: 12px; padding: 10px 16px; background: var(--bg-card); border-bottom: 1px solid var(--border-color); }
.browser-dots { display: flex; gap: 6px; }
.dot { width: 10px; height: 10px; border-radius: 50%; }
.dot.red { background: #ff5f57; }
.dot.yellow { background: #ffbd2e; }
.dot.green { background: #28c840; }
.browser-url-bar { flex: 1; padding: 6px 14px; background: var(--bg-content); border-radius: 6px; font-size: 13px; color: var(--text-tertiary); }
.browser-content { padding: 60px 40px; min-height: 300px; display: flex; align-items: center; justify-content: center; }
.preview-placeholder { text-align: center; color: var(--text-tertiary); }

/* ========== API文档页面 ========== */
.api-container { display: flex; min-height: calc(100vh - var(--header-h) - var(--banner-h)); }
.api-sidebar {
  width: 240px; background: var(--bg-content); border-right: 1px solid var(--border-color);
  padding: 24px 0; overflow-y: auto; flex-shrink: 0;
}
.api-nav { margin-bottom: 24px; }
.api-nav h4 { font-size: 12px; font-weight: 600; color: var(--text-tertiary); padding: 0 20px; margin-bottom: 8px; text-transform: uppercase; letter-spacing: 0.5px; }
.api-nav-item {
  display: block; padding: 8px 20px; font-size: 14px; color: var(--text-secondary);
  text-decoration: none; transition: all 0.15s; cursor: pointer;
}
.api-nav-item:hover { background: var(--bg-card); color: var(--accent); }
.api-nav-item.active { background: var(--accent-light); color: var(--accent); font-weight: 500; }
.api-content { flex: 1; padding: 36px; overflow-y: auto; }
.api-section { max-width: 800px; }
.api-section h2 { font-size: 24px; font-weight: 700; margin-bottom: 16px; }
.api-section h3 { font-size: 18px; font-weight: 600; margin: 28px 0 12px; }
.api-section p { font-size: 14px; color: var(--text-secondary); line-height: 1.7; margin-bottom: 12px; }
.api-endpoint { display: flex; align-items: center; gap: 10px; padding: 12px 16px; background: var(--bg-card); border-radius: var(--radius-md); margin: 12px 0; }
.method { padding: 4px 10px; border-radius: 4px; font-size: 12px; font-weight: 700; color: #fff; }
.method.get { background: #3674FC; }
.api-endpoint code { font-size: 14px; color: var(--text-primary); }
.api-table { width: 100%; border-collapse: collapse; margin: 12px 0 24px; font-size: 14px; }
.api-table th { background: var(--bg-card); padding: 10px 14px; text-align: left; font-weight: 600; border-bottom: 2px solid var(--border-color); }
.api-table td { padding: 10px 14px; border-bottom: 1px solid var(--border-color); }
.api-table code { background: var(--accent-light); color: var(--accent); padding: 2px 6px; border-radius: 4px; font-size: 13px; }
.code-block {
  background: #1e1e2e; color: #d4d4d4; padding: 20px; border-radius: var(--radius-md);
  font-size: 13px; line-height: 1.6; overflow-x: auto; margin: 12px 0 24px; font-family: 'Consolas', 'Monaco', monospace;
}

/* ========== Responsive ========== */
@media (max-width: 1200px) {
  .right-panel { display: none; }
}
@media (max-width: 768px) {
  .sidebar { display: none; }
  .content { border-radius: 0; }
  .center-panel { padding: 20px 16px 10px; }
  .content-tabs { padding: 0 12px; overflow-x: auto; }
  .demo-cards { flex-direction: column; }
  .demo-card { min-width: auto; }
  .top-banner { display: none; }
  .main-container { height: calc(100vh - var(--header-h)); }
}

/* ========== Animations ========== */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}
.ai-greeting,
.demo-card:nth-child(1),
.demo-card:nth-child(2) {
  animation: fadeInUp 0.5s ease-out both;
}
.demo-card:nth-child(2) { animation-delay: 0.1s; }

/* Scrollbar */
::-webkit-scrollbar { width: 5px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 10px; }
::-webkit-scrollbar-thumb:hover { background: #d0d5dd; }


/* ===== 从 yd6 追加：Footer + 下载页 + 其他页面样式 ===== */
/* ===== Footer (参考有道官网) ===== */
.site-footer {
  background: #F1F6FF;
  padding: 48px 0 0;
  font-size: 11px;
  color: #333;
}
.ft-main {
  display: flex;
  justify-content: space-between;
  gap: 40px;
  padding-bottom: 32px;
  border-bottom: 1px solid #DDE6F6;
}
.ft-left {
  flex-shrink: 0;
  width: 180px;
}
.ft-logo {
  height: 32px;
  margin-bottom: 16px;
}
.ft-qrcode-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
}
.ft-qrcode {
  height: 72px;
  border-radius: 6px;
}
.ft-qrcode-text {
  font-size: 10px;
  color: #666;
  line-height: 1.5;
}
.ft-channels {
  margin-top: 8px;
}
.ft-channel-title {
  font-size: 10px;
  color: #999;
  display: block;
  margin-bottom: 8px;
}
.ft-channel-icons {
  display: flex;
  gap: 10px;
}
.ch-icon {
  height: 24px;
  width: 24px;
  cursor: pointer;
}
.ft-links {
  display: flex;
  gap: 40px;
  flex: 1;
  justify-content: flex-end;
}
.ft-list {
  list-style: none;
  min-width: 90px;
}
.ft-title {
  font-weight: 600;
  font-size: 12px;
  color: #222;
  margin-bottom: 12px;
}
.ft-list li {
  margin-bottom: 8px;
}
.ft-list a {
  font-size: 11px;
  color: #666;
  transition: color .2s;
}
.ft-list a:hover {
  color: #E4393C;
}
.ft-copyright {
  text-align: center;
  padding: 16px 0 8px;
  font-size: 10px;
  color: #999;
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}
.ft-copyright a {
  color: #999;
  font-size: 10px;
}
.ft-copyright a:hover { color: #E4393C; }
.ft-report {
  text-align: center;
  padding: 4px 0 20px;
  font-size: 10px;
  color: #999;
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
  border-bottom: 1px solid #DDE6F6;
  margin-bottom: 0;
}
.ft-report a {
  color: #999;
  font-size: 10px;
}
.ft-report a:hover { color: #E4393C; }

/* ===== 多平台下载页面 ===== */
.dl-page {
  padding: 60px 0 80px;
  background: #fff;
}
.dl-title {
  font-size: 40px;
  font-weight: 400;
  color: #2A2B2E;
  text-align: center;
  margin-bottom: 8px;
}
.dl-divider {
  width: 100%;
  height: 1px;
  background: linear-gradient(90deg, transparent, #E4E7ED, transparent);
  margin-bottom: 16px;
}
.dl-protocol {
  text-align: center;
  font-size: 13px;
  color: #666;
  margin-bottom: 6px;
}
.dl-link {
  color: #4A90D9;
  text-decoration: none;
}
.dl-link:hover { text-decoration: underline; }
.dl-changelog {
  display: block;
  text-align: center;
  font-size: 13px;
  color: #4A90D9;
  text-decoration: none;
  margin-bottom: 40px;
}
.dl-changelog:hover { text-decoration: underline; }

/* 下载项：左侧设备图 + 右侧信息 */
.dl-item {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 80px;
  padding: 32px 129px;
  margin-bottom: 32px;
  background: rgba(244,245,247,0.5);
  border-radius: 16px;
}
.dl-preview {
  width: 371px;
  height: auto;
  flex-shrink: 0;
}
.dl-info {
  min-width: 300px;
}
.dl-os-name {
  font-size: 28px;
  font-weight: 400;
  color: #2A2B2E;
  margin-bottom: 24px;
}
.dl-desc {
  font-size: 14px;
  color: #999;
  margin-bottom: 12px;
}

/* 按钮组 */
.dl-btns {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-top: 32px;
}
.dl-btns-grid {
  display: grid;
  grid-template-columns: repeat(2, 192px);
  gap: 10px;
  margin-top: 2px;
}
.dl-btn-img {
  height: 48px;
  cursor: pointer;
  transition: opacity .2s;
  border: none;
  background: none;
  padding: 0;
}
.dl-btn-img:hover { opacity: .85; }

/* Linux 包按钮 */
.dl-pkg-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 192px;
  height: 48px;
  background: #5B8DEF;
  color: #fff;
  border-radius: 6px;
  font-size: 13px;
  cursor: pointer;
  transition: background .2s;
  text-align: center;
  line-height: 1.2;
  padding: 4px 12px;
  box-sizing: border-box;
}
.dl-pkg-btn:hover {
  background: #4A7DD9;
}

/* ===== Release Notes (更新日志) ===== */
.cl-page {
  padding: 60px 0 80px;
  background: #fff;
}
.cl-title {
  font-size: 40px;
  font-weight: 400;
  color: #2A2B2E;
  text-align: center;
  margin-bottom: 40px;
}
.cl-box {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 20px;
}
.cl-item {
  padding-bottom: 31px;
  margin-top: 32px;
  border-bottom: 1px dashed rgba(220,223,229,0.6);
}
.cl-item:first-child { margin-top: 0; }
.cl-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}
.cl-ver {
  font-size: 18px;
  font-weight: 600;
  color: #2A2B2E;
}
.cl-date {
  font-size: 14px;
  color: #626469;
}
.cl-desc {
  list-style: none;
  padding: 0;
  margin: 0;
}
.cl-desc li {
  font-size: 14px;
  color: #626469;
  line-height: 21px;
  padding: 3px 0;
  position: relative;
  padding-left: 16px;
}
.cl-desc li::before {
  content: '-';
  position: absolute;
  left: 0;
  color: #999;
}

/* ===== 法律页面（服务条款/隐私政策） ===== */
.legal-page {
  padding: 60px 0 80px;
  background: #fff;
}
.legal-title {
  font-size: 32px;
  font-weight: 400;
  color: #2A2B2E;
  text-align: center;
  margin-bottom: 40px;
}
.legal-body {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 20px;
  font-size: 14px;
  color: #555;
  line-height: 1.8;
}
.legal-body p { margin-bottom: 16px; }
.legal-body h3 {
  font-size: 18px;
  font-weight: 600;
  color: #2A2B2E;
  margin: 28px 0 12px;
}
.legal-body h4 {
  font-size: 16px;
  font-weight: 600;
  color: #333;
  margin: 24px 0 10px;
}
.legal-body ul {
  padding-left: 20px;
  margin-bottom: 16px;
}
.legal-body ul li {
  line-height: 1.8;
  color: #555;
}


/* ===== About 页面 ===== */
.about-banner {
  padding: 80px 0 60px;
  background: linear-gradient(180deg, #FFF5F5 0%, #FFFFFF 100%);
  text-align: center;
}
.about-banner h1 {
  font-size: 36px;
  font-weight: 700;
  color: #2A2B2E;
  margin-bottom: 12px;
}
.about-banner p {
  font-size: 18px;
  color: var(--text-light);
}

/* 公司介绍 */
.about-intro {
  padding: 80px 0;
  background: #fff;
}
.about-intro-inner {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 60px;
  align-items: start;
}
.about-intro-text h2 {
  font-size: 28px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 20px;
}
.about-intro-lead {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-main);
  line-height: 1.6;
  margin-bottom: 16px;
}
.about-intro-text p {
  font-size: 15px;
  color: var(--text-sub);
  line-height: 1.8;
  margin-bottom: 12px;
}
.highlight {
  color: var(--primary);
  font-weight: 600;
}
.about-intro-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}
.stat-item {
  background: var(--bg-light);
  border-radius: 12px;
  padding: 24px 20px;
  text-align: center;
}
.stat-num {
  display: block;
  font-size: 32px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
}
.stat-label {
  font-size: 14px;
  color: var(--text-light);
}

/* 产品功能 */
.about-product {
  padding: 80px 0;
  background: var(--bg-light);
}
.section-title {
  font-size: 28px;
  font-weight: 700;
  text-align: center;
  color: #2A2B2E;
  margin-bottom: 8px;
}
.section-subtitle {
  font-size: 16px;
  color: var(--text-light);
  text-align: center;
  margin-bottom: 48px;
}
.product-features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.pf-card {
  background: #fff;
  border-radius: 12px;
  padding: 32px 24px;
  text-align: center;
  transition: box-shadow 0.2s;
}
.pf-card:hover {
  box-shadow: var(--shadow);
}
.pf-icon {
  font-size: 36px;
  margin-bottom: 16px;
}
.pf-card h3 {
  font-size: 18px;
  font-weight: 600;
  color: #2A2B2E;
  margin-bottom: 12px;
}
.pf-card p {
  font-size: 14px;
  color: var(--text-sub);
  line-height: 1.6;
}

/* 产品生态 */
.about-ecosystem {
  padding: 80px 0;
  background: #fff;
}
.eco-category {
  margin-bottom: 48px;
}
.eco-category:last-child {
  margin-bottom: 0;
}
.eco-category-title {
  font-size: 20px;
  font-weight: 600;
  color: #2A2B2E;
  margin-bottom: 20px;
  padding-left: 12px;
  border-left: 4px solid var(--primary);
}
.eco-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
.eco-card {
  background: var(--bg-light);
  border-radius: 10px;
  padding: 20px;
  transition: box-shadow 0.2s;
}
.eco-card:hover {
  box-shadow: var(--shadow);
}
.eco-card h4 {
  font-size: 15px;
  font-weight: 600;
  color: #2A2B2E;
  margin-bottom: 6px;
}
.eco-card p {
  font-size: 13px;
  color: var(--text-light);
  line-height: 1.5;
}

/* FAQ */
.about-faq {
  padding: 80px 0;
  background: var(--bg-light);
}
.faq-list {
  max-width: 720px;
  margin: 0 auto;
}
.faq-item {
  background: #fff;
  border-radius: 10px;
  margin-bottom: 12px;
  overflow: hidden;
}
.faq-question {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 18px 24px;
  cursor: pointer;
  font-size: 15px;
  font-weight: 500;
  color: #2A2B2E;
  transition: background 0.2s;
}
.faq-question:hover {
  background: #fafafa;
}
.faq-arrow {
  font-size: 12px;
  color: var(--text-light);
  transition: transform 0.2s;
}
.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
}
.faq-answer p {
  padding: 0 24px 18px;
  font-size: 14px;
  color: var(--text-sub);
  line-height: 1.7;
}
.faq-answer a {
  color: var(--primary);
}
.faq-item.active .faq-answer {
  max-height: 200px;
}
.faq-item.active .faq-arrow {
  transform: rotate(180deg);
}

/* 联系我们 */
.about-contact {
  padding: 80px 0;
  background: #fff;
}
.contact-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  max-width: 900px;
  margin: 0 auto;
}
.contact-card {
  text-align: center;
  padding: 32px 16px;
  background: var(--bg-light);
  border-radius: 12px;
}
.contact-icon {
  font-size: 32px;
  margin-bottom: 12px;
}
.contact-card h4 {
  font-size: 15px;
  font-weight: 600;
  color: #2A2B2E;
  margin-bottom: 8px;
}
.contact-card p {
  font-size: 14px;
  color: var(--text-sub);
}
.contact-card a {
  color: var(--primary);
}
.contact-qr {
  margin-top: 12px;
}
.contact-qr img {
  width: 80px;
  height: 80px;
  border-radius: 6px;
}
.contact-qr span {
  display: block;
  font-size: 12px;
  color: var(--text-light);
  margin-top: 6px;
}

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .research-grid,
  .define-grid,
  .feature-layout {
    grid-template-columns: 1fr;
    gap: 32px;
  }
  .feature-layout.reverse { direction: ltr; }
  .type-row { text-align: center; }
  .type-row-full { grid-column: 1 / -1; flex-direction: column; }
  .type-row-full .type-row-img { max-width: 100%; }
  .bottom-infos { grid-template-columns: 1fr; }
  .ft-main { flex-direction: column; gap: 32px; }
  .ft-links { gap: 24px; flex-wrap: wrap; justify-content: flex-start; }
  .ft-left { width: 100%; }
  /* 下载页响应式 */
  .dl-item { flex-direction: column; padding: 40px 24px; gap: 24px; text-align: center; }
  .dl-preview { width: 280px; }
  .dl-btns { justify-content: center; }
  .dl-btns-grid { grid-template-columns: repeat(2, 160px); gap: 8px; }
  .dl-pkg-btn { width: 160px; height: 42px; font-size: 12px; }
  /* About 页面响应式 */
  .about-intro-inner { grid-template-columns: 1fr; gap: 40px; }
  .about-intro-stats { grid-template-columns: repeat(2, 1fr); }
  .product-features { grid-template-columns: repeat(2, 1fr); }
  .eco-grid { grid-template-columns: repeat(2, 1fr); }
  .contact-grid { grid-template-columns: repeat(2, 1fr); }
  .about-banner h1 { font-size: 28px; }
}
@media (max-width: 640px) {
  .container { padding:0 16px; }
  .nav { display:none; }
  .mobile-menu-btn { display:flex; }
  .header .container { position:relative; }
  .hero-section { height: auto; padding: 40px 0 30px; }
  .hero-banner { position: relative; top: 0; height: auto; }
  .hero-content { position: relative; top: 0; left: 0; transform: none; width: 100%; padding: 0 16px; }
  .hero-logo { height: 28px; margin: 20px auto 0; }
  .hero-title { height: 50px; margin: 15px auto 20px; }
  .hero-tips-img { position: static; margin-bottom: 10px; }
  .hero-computer { position: static; transform: none; width: 100%; max-width: 500px; }
  .hero-dl-row { flex-direction: column; gap: 8px; align-items: center; }
  .hero-dl-btn { max-width: 200px; }
  .hero-links { flex-direction: column; gap: 6px; }
  /* About 页面超小屏 */
  .product-features { grid-template-columns: 1fr; }
  .eco-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .about-intro-stats { grid-template-columns: 1fr 1fr; }
  .stat-num { font-size: 24px; }
  .bottom-cta { height: auto; padding: 40px 0; background-size: cover; }
  .bottom-cta-inner { padding-top: 40px; width: 100%; }
  .bottom-cta-title { font-size: 24px; line-height: 32px; }
  .bottom-cta-honor { width: 100%; flex-wrap: wrap; justify-content: center; gap: 12px; margin: 30px auto; }
  .honor-item { width: 140px; height: 170px; }
  .bottom-cta-dl-btn { width: 180px; }
  /* Footer 超小屏 */
  .ft-main { flex-direction: column; }
  .ft-left { width: 100%; }
  .ft-links { gap: 20px; flex-wrap: wrap; }
  .ft-qrcode-wrap { display: none; }
  .ft-copyright, .ft-report { font-size: 9px; }
  /* 下载页超小屏 */
  .dl-item { padding: 24px 16px; }
  .dl-preview { width: 200px; }
  .dl-btns-grid { grid-template-columns: 1fr; max-width: 200px; }
  /* Features 页面超小屏 */
  .section-title { font-size: 22px; }
  .define-grid, .feature-layout { gap: 20px; }
  .type-row { flex-direction: column; }
  .type-row-img { max-width: 100%; }
  /* Terms/Privacy 页面 */
  .content-page { padding: 30px 0; }
  .content-page h2 { font-size: 20px; }
}