/* =========================================================
   ClawSearch 建材行业垂直情报平台 - 主样式表
   v2.0 (2026-08-29)  — 类名与 index.html 完全对齐
   ========================================================= */

:root {
  --primary: #1a56db;
  --primary-dark: #1e40af;
  --primary-light: #3b82f6;
  --secondary: #059669;
  --accent: #d97706;
  --bg: #ffffff;
  --bg-alt: #f8fafc;
  --text: #1f2937;
  --text-light: #6b7280;
  --border: #e5e7eb;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 8px 20px -6px rgba(0, 0, 0, 0.12);
  --shadow-lg: 0 20px 40px -12px rgba(0, 0, 0, 0.18);
  --radius: 14px;
  --nav-h: 70px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  /* 锚点定位时避开固定导航栏 */
  scroll-padding-top: var(--nav-h);
  font-size: 16px;
}

body {
  /* 零外部字体依赖：按平台优先回退，Cloudflare Pages 和国内访问均秒出字 */
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
               'Hiragino Sans GB', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.75;
  overflow-x: hidden;
  /* 平滑字体渲染 */
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* =========================================================
   NAVIGATION
   ========================================================= */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-h);
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: var(--transition);
}

.navbar.scrolled {
  border-bottom-color: var(--border);
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  text-decoration: none;
  font-size: 1.35rem;
  font-weight: 900;
  letter-spacing: -0.02em;
  flex-shrink: 0;
}

.logo-icon {
  font-size: 1.6rem;
  line-height: 1;
}

.logo-text {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  list-style: none;
}

.nav-link {
  display: inline-block;
  padding: 0.5rem 0.9rem;
  text-decoration: none;
  color: var(--text-light);
  font-weight: 500;
  font-size: 0.95rem;
  border-radius: 8px;
  transition: var(--transition);
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--primary);
  background: rgba(26, 86, 219, 0.06);
}

.nav-link.active {
  color: var(--primary);
  font-weight: 600;
}

.nav-cta {
  margin-left: 0.5rem;
  padding: 0.5rem 1.1rem;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff !important;
  border-radius: 8px;
  font-weight: 600;
  box-shadow: 0 2px 8px rgba(26, 86, 219, 0.28);
}

.nav-cta:hover {
  background: linear-gradient(135deg, var(--primary-dark), #172554);
  color: #fff !important;
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(26, 86, 219, 0.34);
}

/* 汉堡按钮 */
.mobile-menu-btn {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 42px;
  height: 42px;
  padding: 0 9px;
  background: none;
  border: none;
  cursor: pointer;
  border-radius: 8px;
  transition: var(--transition);
}

.mobile-menu-btn:hover {
  background: var(--bg-alt);
}

.mobile-menu-btn span {
  display: block;
  width: 100%;
  height: 2.5px;
  background: var(--text);
  border-radius: 2px;
  transition: var(--transition);
}

.mobile-menu-btn.active span:nth-child(1) {
  transform: translateY(7.5px) rotate(45deg);
}

.mobile-menu-btn.active span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0.4);
}

.mobile-menu-btn.active span:nth-child(3) {
  transform: translateY(-7.5px) rotate(-45deg);
}

/* =========================================================
   HERO
   ========================================================= */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: calc(var(--nav-h) + 3rem) 2rem 5rem;
  background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 45%, #f0fdf4 100%);
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.hero-bg::before,
.hero-bg::after {
  content: '';
  position: absolute;
  border-radius: 50%;
  filter: blur(2px);
}

.hero-bg::before {
  top: -22%;
  right: -12%;
  width: 720px;
  height: 720px;
  background: radial-gradient(circle, rgba(26, 86, 219, 0.13) 0%, transparent 68%);
  animation: float 22s ease-in-out infinite;
}

.hero-bg::after {
  bottom: -28%;
  left: -8%;
  width: 560px;
  height: 560px;
  background: radial-gradient(circle, rgba(5, 150, 105, 0.11) 0%, transparent 68%);
  animation: float 17s ease-in-out infinite reverse;
}

@keyframes float {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50%      { transform: translate(-24px, -30px) scale(1.06); }
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 4rem;
  align-items: center;
}

/* grid 子项：允许内容收缩，避免长单词撑破布局 */
.hero-text {
  min-width: 0;
}

.hero-title {
  font-size: clamp(2.4rem, 5vw, 3.6rem);
  font-weight: 900;
  line-height: 1.18;
  letter-spacing: -0.02em;
  margin-bottom: 1.25rem;
  color: var(--text);
}

.hero-title .highlight {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 0.85rem;
}

.hero-desc {
  font-size: 1.02rem;
  color: var(--text-light);
  max-width: 34rem;
  margin-bottom: 2rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 2.75rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 1.9rem;
  border: none;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  font-family: inherit;
  text-decoration: none;
  cursor: pointer;
  transition: var(--transition);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff;
  box-shadow: 0 4px 14px rgba(26, 86, 219, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 24px rgba(26, 86, 219, 0.36);
}

.btn-secondary {
  background: #fff;
  color: var(--text);
  border: 1.5px solid var(--border);
}

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

.hero-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 2.5rem;
  padding-top: 2rem;
  border-top: 1px solid rgba(31, 41, 55, 0.1);
}

.stat-item {
  display: flex;
  flex-direction: column;
}

.stat-number {
  font-size: 2.1rem;
  font-weight: 900;
  line-height: 1.1;
  color: var(--primary);
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-light);
  margin-top: 0.15rem;
}

/* 搜索演示框 */
.hero-visual {
  display: flex;
  justify-content: center;
}

.search-demo {
  width: 100%;
  max-width: 460px;
  background: #fff;
  border-radius: 20px;
  padding: 1.9rem;
  box-shadow: var(--shadow-lg);
  animation: slideUp 0.9s cubic-bezier(0.16, 1, 0.3, 1) both;
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(34px); }
  to   { opacity: 1; transform: translateY(0); }
}

.search-box {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.55rem 0.55rem 0.55rem 1.1rem;
  border: 2px solid var(--border);
  border-radius: 12px;
  transition: var(--transition);
}

.search-box:focus-within {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px rgba(26, 86, 219, 0.1);
}

.search-icon {
  font-size: 1.1rem;
  flex-shrink: 0;
}

.search-input {
  flex: 1;
  min-width: 0;
  border: none;
  outline: none;
  font-size: 1rem;
  font-family: inherit;
  color: var(--text);
  background: transparent;
}

.search-input::placeholder {
  color: #9ca3af;
}

.search-btn {
  padding: 0.7rem 1.4rem;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff;
  border: none;
  border-radius: 9px;
  font-weight: 600;
  font-size: 0.95rem;
  font-family: inherit;
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}

.search-btn:hover {
  filter: brightness(1.08);
  transform: translateY(-1px);
}

.search-suggestions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.15rem;
}

.suggestion-tag {
  padding: 0.42rem 0.95rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: 0.83rem;
  color: var(--text-light);
  cursor: pointer;
  transition: var(--transition);
  user-select: none;
}

.suggestion-tag:hover {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
  transform: translateY(-1px);
}

/* =========================================================
   SECTION 通用
   ========================================================= */
section {
  padding: 6rem 2rem;
}

.section-title {
  text-align: center;
  font-size: clamp(1.85rem, 3.5vw, 2.5rem);
  font-weight: 900;
  letter-spacing: -0.02em;
  color: var(--text);
  margin-bottom: 0.75rem;
}

.section-subtitle {
  text-align: center;
  font-size: 1.08rem;
  color: var(--text-light);
  max-width: 40rem;
  margin: 0 auto 3.5rem;
}

/* =========================================================
   FEATURES
   ========================================================= */
.features {
  background: var(--bg);
}

.features-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.75rem;
}

.feature-card {
  position: relative;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem 1.75rem;
  overflow: hidden;
  transition: var(--transition);
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.35s ease;
}

.feature-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.feature-card:hover::before {
  transform: scaleX(1);
}

.feature-icon {
  width: 58px;
  height: 58px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  border-radius: 13px;
  background: linear-gradient(135deg, var(--primary-light), var(--primary));
  color: #fff;
  margin-bottom: 1.25rem;
  box-shadow: 0 6px 16px rgba(26, 86, 219, 0.24);
}

.feature-card h3 {
  font-size: 1.18rem;
  font-weight: 700;
  margin-bottom: 0.6rem;
  color: var(--text);
}

.feature-card p {
  font-size: 0.95rem;
  color: var(--text-light);
}

/* =========================================================
   CATEGORIES
   ========================================================= */
.categories {
  background: var(--bg-alt);
}

.categories-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(215px, 1fr));
  gap: 1.5rem;
}

.category-card {
  position: relative;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.85rem 1.5rem;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
}

.category-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.category-icon {
  font-size: 2.75rem;
  line-height: 1;
  display: block;
  margin-bottom: 0.9rem;
}

.category-card h3 {
  font-size: 1.12rem;
  font-weight: 700;
  margin-bottom: 0.55rem;
  color: var(--text);
}

.category-desc {
  font-size: 0.85rem;
  color: var(--text-light);
  margin-bottom: 1.1rem;
  min-height: 3.2rem;
}

.category-tags {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.4rem;
}

.category-tags li {
  padding: 0.26rem 0.7rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: 0.75rem;
  color: var(--text-light);
}

/* 核心领域（外加剂）突出显示 */
.category-card.featured {
  border-color: rgba(217, 119, 6, 0.4);
  background: linear-gradient(180deg, #fffbeb 0%, #ffffff 55%);
}

.category-card.featured:hover {
  border-color: var(--accent);
}

/* 外加剂：标签同步为琥珀色，呼应"核心领域"定位 */
.category-admixture .category-tags li {
  background: #fffbeb;
  border-color: rgba(217, 119, 6, 0.28);
  color: #92400e;
}

.category-badge {
  position: absolute;
  top: -11px;
  left: 50%;
  transform: translateX(-50%);
  padding: 0.22rem 0.85rem;
  background: linear-gradient(135deg, #f59e0b, var(--accent));
  color: #fff;
  font-size: 0.7rem;
  font-weight: 700;
  border-radius: 20px;
  white-space: nowrap;
  box-shadow: 0 3px 10px rgba(217, 119, 6, 0.32);
}

/* =========================================================
   CAPABILITIES
   ========================================================= */
.capabilities {
  background: var(--bg);
}

.capabilities-content {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1.05fr;
  gap: 3rem;
  align-items: start;
}

.capability-list {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.capability-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 1.15rem 1.35rem;
  background: #fff;
  border: 1.5px solid var(--border);
  border-radius: 12px;
  cursor: pointer;
  transition: var(--transition);
}

.capability-item:hover {
  border-color: rgba(26, 86, 219, 0.45);
  background: #fbfdff;
  transform: translateX(4px);
}

.capability-item.active {
  border-color: var(--primary);
  background: linear-gradient(135deg, rgba(26, 86, 219, 0.06), rgba(5, 150, 105, 0.04));
  box-shadow: 0 4px 16px rgba(26, 86, 219, 0.12);
}

.capability-number {
  flex-shrink: 0;
  font-size: 1.35rem;
  font-weight: 900;
  line-height: 1.3;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.capability-info h3 {
  font-size: 1.02rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
  color: var(--text);
}

.capability-info p {
  font-size: 0.88rem;
  color: var(--text-light);
  line-height: 1.6;
}

/* 演示面板 */
.capability-demo {
  position: sticky;
  top: calc(var(--nav-h) + 1.5rem);
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-md);
}

.demo-header {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.85rem 1.25rem;
  background: var(--bg-alt);
  border-bottom: 1px solid var(--border);
}

.demo-dot {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  flex-shrink: 0;
}

.demo-dot.red    { background: #ef4444; }
.demo-dot.yellow { background: #f59e0b; }
.demo-dot.green  { background: #10b981; }

.demo-title {
  margin-left: 0.5rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-light);
}

.demo-content {
  padding: 1.5rem;
}

/* 切换能力项时重放内容入场动画 —— .fade-swap 由 main.js 动态添加 */
.capability-demo.fade-swap .demo-content {
  animation: fadeSwap 0.35s ease;
}

@keyframes fadeSwap {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.demo-query {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.5rem;
  padding: 0.85rem 1rem;
  background: var(--bg-alt);
  border-left: 3px solid var(--primary);
  border-radius: 0 8px 8px 0;
  margin-bottom: 1.35rem;
}

.query-label {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-light);
  flex-shrink: 0;
}

.query-text {
  font-family: 'Courier New', Consolas, monospace;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--primary);
  word-break: break-word;
}

.demo-result {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
}

.result-item {
  padding: 1rem 1.15rem;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 10px;
  transition: var(--transition);
}

.result-item:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow);
  transform: translateX(3px);
}

.result-item h4 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.35rem;
}

.result-item p {
  font-size: 0.87rem;
  color: var(--text-light);
  line-height: 1.65;
}

/* =========================================================
   CASES
   ========================================================= */
.cases {
  background: var(--bg-alt);
}

.cases-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.75rem;
}

.case-card {
  display: flex;
  flex-direction: column;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: var(--transition);
}

.case-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}

.case-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.9rem 1.4rem;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
}

.case-category {
  padding: 0.24rem 0.8rem;
  background: rgba(255, 255, 255, 0.22);
  color: #fff;
  border-radius: 20px;
  font-size: 0.76rem;
  font-weight: 600;
}

.case-tag {
  color: rgba(255, 255, 255, 0.92);
  font-size: 0.82rem;
  font-weight: 600;
}

.case-card h3 {
  padding: 1.35rem 1.4rem 0.5rem;
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--text);
  line-height: 1.5;
}

.case-desc {
  flex: 1;
  padding: 0 1.4rem 1.25rem;
  font-size: 0.9rem;
  color: var(--text-light);
}

.case-metrics {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding: 1rem 1.4rem;
  border-top: 1px solid var(--border);
  background: #fcfdfe;
}

.metric {
  padding: 0.3rem 0.75rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 7px;
  font-size: 0.78rem;
  color: var(--text-light);
  font-weight: 500;
}

/* =========================================================
   ABOUT
   ========================================================= */
.about {
  background: var(--bg);
}

.about-content {
  max-width: 1100px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 3.5rem;
  align-items: center;
}

.about-text h3 {
  font-size: 1.45rem;
  font-weight: 800;
  margin-bottom: 1rem;
  color: var(--text);
}

.about-text > p {
  font-size: 1rem;
  color: var(--text-light);
  margin-bottom: 1.1rem;
}

.about-features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 0.75rem;
  margin-top: 1.75rem;
}

.about-feature {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.93rem;
  color: var(--text);
  font-weight: 500;
}

.feature-check {
  flex-shrink: 0;
  width: 22px;
  height: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--secondary), #047857);
  color: #fff;
  border-radius: 50%;
  font-size: 0.72rem;
  font-weight: 700;
}

.about-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.15rem;
}

.stat-card {
  padding: 1.75rem 1.25rem;
  background: linear-gradient(160deg, #f8fafc, #eff6ff);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-align: center;
  transition: var(--transition);
}

.stat-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: var(--primary);
}

.stat-value {
  font-size: 2rem;
  font-weight: 900;
  line-height: 1.15;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-card .stat-label {
  font-size: 0.83rem;
  color: var(--text-light);
  margin-top: 0.3rem;
}

/* =========================================================
   FOOTER
   ========================================================= */
.footer {
  background: #111827;
  color: #fff;
  padding: 4rem 2rem 2rem;
}

/* footer 实际结构：.footer-brand + .footer-links（内含 3 个 .footer-column） */
.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.3fr 2fr;
  gap: 3rem;
}

.footer-brand {
  min-width: 0;
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  min-width: 0;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  font-size: 1.3rem;
  font-weight: 900;
  margin-bottom: 0.85rem;
}

.footer-desc {
  font-size: 0.9rem;
  color: #9ca3af;
  max-width: 20rem;
}

.footer-column h4 {
  font-size: 0.98rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: #fff;
}

.footer-column a {
  display: block;
  font-size: 0.9rem;
  color: #9ca3af;
  text-decoration: none;
  margin-bottom: 0.6rem;
  transition: var(--transition);
}

.footer-column a:hover {
  color: #fff;
  transform: translateX(3px);
}

.footer-column p {
  font-size: 0.9rem;
  color: #9ca3af;
  margin-bottom: 0.6rem;
}

.footer-bottom {
  max-width: 1200px;
  margin: 3rem auto 0;
  padding-top: 1.75rem;
  border-top: 1px solid #1f2937;
  text-align: center;
  font-size: 0.86rem;
  color: #6b7280;
}

/* =========================================================
   BACK TO TOP
   ========================================================= */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 1.35rem;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: var(--transition);
  z-index: 999;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--primary-dark);
  transform: translateY(-3px);
}

/* =========================================================
   滚动淡入动画
   ========================================================= */
.fade-in {
  opacity: 0;
  transform: translateY(26px);
  transition: opacity 0.65s ease, transform 0.65s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* 尊重用户的"减少动效"系统设置 */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .fade-in {
    opacity: 1;
    transform: none;
  }
}

/* =========================================================
   RESPONSIVE
   ========================================================= */
@media (max-width: 1024px) {
  .hero-content {
    grid-template-columns: 1fr;
    gap: 2.5rem;
    text-align: center;
  }

  .hero-desc {
    margin-left: auto;
    margin-right: auto;
  }

  .hero-actions,
  .hero-stats {
    justify-content: center;
  }

  .capabilities-content {
    grid-template-columns: 1fr;
  }

  .capability-demo {
    position: static;
  }

  .about-content {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .footer-content {
    grid-template-columns: 1fr 1.7fr;
    gap: 2rem;
  }
}

@media (max-width: 820px) {
  .nav-links {
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0.2rem;
    padding: 0.85rem 1.25rem 1.25rem;
    background: #fff;
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-md);
    max-height: calc(100vh - var(--nav-h));
    overflow-y: auto;
    /* 收起状态：不可见且不拦截点击 */
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: var(--transition);
  }

  .nav-links.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

  .nav-link {
    padding: 0.75rem 1rem;
    border-radius: 8px;
    font-size: 1rem;
  }

  .nav-cta {
    margin-left: 0;
    margin-top: 0.5rem;
    text-align: center;
  }

  .mobile-menu-btn {
    display: flex;
  }
}

@media (max-width: 768px) {
  section {
    padding: 4rem 1.5rem;
  }

  .hero {
    padding: calc(var(--nav-h) + 2.5rem) 1.5rem 3.5rem;
  }

  .hero-stats {
    gap: 1.75rem;
  }

  .section-subtitle {
    margin-bottom: 2.5rem;
  }

  .about-stats {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .footer-links {
    grid-template-columns: 1fr;
    gap: 1.75rem;
  }

  .footer-logo {
    justify-content: center;
  }

  .footer-desc {
    margin-left: auto;
    margin-right: auto;
  }

  .footer-column a:hover {
    transform: none;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 1.25rem;
  }

  .hero-actions {
    flex-direction: column;
  }

  .hero-actions .btn {
    width: 100%;
  }

  .hero-stats {
    flex-direction: column;
    gap: 1rem;
    align-items: center;
  }

  .stat-item {
    flex-direction: row;
    align-items: baseline;
    gap: 0.5rem;
  }

  .search-box {
    flex-wrap: wrap;
  }

  .search-input {
    min-width: 8rem;
  }

  .search-btn {
    flex: 1;
  }

  .about-stats {
    grid-template-columns: 1fr;
  }

  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
  }
}