/* 基础与变量 */
:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-text: #1f2937;
  --color-text-muted: #6b7280;
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-border: #e5e7eb;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --header-height: 64px;
  --container-max: 960px;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,.08);
  --shadow-lg: 0 10px 40px rgba(0,0,0,.1);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
}

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 20px;
}

/* 导航 */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow);
}

.header-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 20px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
}

.logo:hover {
  text-decoration: none;
  opacity: .9;
}

.nav {
  display: flex;
  gap: 28px;
}

.nav a {
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.95rem;
}

.nav a:hover {
  color: var(--color-primary);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  border: none;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%231f2937'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M4 6h16M4 12h16M4 18h16'/%3E%3C/svg%3E") center/24px no-repeat;
  cursor: pointer;
}

@media (max-width: 768px) {
  .nav-toggle {
    display: block;
  }
  .nav {
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    flex-direction: column;
    padding: 20px;
    gap: 12px;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    display: none;
  }
  .nav.open {
    display: flex;
  }
}

/* Banner */
.banner {
  min-height: 420px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #1e3a5f 0%, #2563eb 50%, #3b82f6 100%);
  color: #fff;
  text-align: center;
  padding: 60px 20px;
}

.banner-inner {
  max-width: 640px;
}

.banner-title {
  margin: 0 0 16px;
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  line-height: 1.3;
}

.banner-desc {
  margin: 0 0 28px;
  font-size: 1.05rem;
  opacity: .95;
}

.btn {
  display: inline-block;
  padding: 12px 28px;
  font-size: 1rem;
  font-weight: 500;
  border-radius: var(--radius);
  cursor: pointer;
  transition: opacity .2s, transform .15s;
}

.btn:hover {
  opacity: .9;
  transform: translateY(-1px);
}

.btn-primary {
  background: #fff;
  color: var(--color-primary);
  border: none;
  text-decoration: none;
}

.btn-primary:hover {
  text-decoration: none;
}

/* 通用区块 */
.section {
  padding: 72px 0;
}

.section:nth-of-type(even) {
  background: var(--color-bg-alt);
}

.section-title {
  margin: 0 0 12px;
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--color-text);
  text-align: center;
}

.section-desc {
  margin: 0 0 40px;
  text-align: center;
  color: var(--color-text-muted);
  max-width: 560px;
  margin-left: auto;
  margin-right: auto;
}

/* 产品卡片 */
.product-cards {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

.product-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: center;
}

.product-card.reverse {
  direction: rtl;
}

.product-card.reverse > * {
  direction: ltr;
}

.product-card-visual {
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  background: var(--color-bg-alt);
  max-width: 360px;
  margin: 0 auto;
}

.product-img {
  width: 100%;
  height: auto;
  max-height: 520px;
  object-fit: contain;
  object-position: top center;
  display: block;
}

.product-card-content h3 {
  margin: 0 0 12px;
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-primary);
}

.product-card-content p {
  margin: 0;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

@media (max-width: 768px) {
  .product-card,
  .product-card.reverse {
    grid-template-columns: 1fr;
    direction: ltr;
    gap: 24px;
  }
  .product-card-visual {
    max-width: 280px;
  }
  .product-img {
    max-height: 420px;
  }
}

/* 功能特点 */
.feature-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.feature-item {
  padding: 24px;
  background: var(--color-bg);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  text-align: center;
  transition: box-shadow .2s, border-color .2s;
}

.feature-item:hover {
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
}

.feature-icon {
  font-size: 2rem;
  display: block;
  margin-bottom: 12px;
}

.feature-item h4 {
  margin: 0 0 8px;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-text);
}

.feature-item p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

@media (max-width: 900px) {
  .feature-list {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 500px) {
  .feature-list {
    grid-template-columns: 1fr;
  }
}

/* 解决方案 */
.solution-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.solution-card {
  padding: 28px;
  background: var(--color-bg);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
}

.solution-card h4 {
  margin: 0 0 12px;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-primary);
}

.solution-card p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

@media (max-width: 768px) {
  .solution-grid {
    grid-template-columns: 1fr;
  }
}

/* 联系我们 */
.contact-info {
  max-width: 480px;
  margin: 0 auto;
  padding: 32px;
  background: var(--color-bg);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  text-align: center;
}

.contact-info p {
  margin: 0 0 8px;
  color: var(--color-text-muted);
}

.contact-info p:last-child {
  margin-bottom: 0;
}

.contact-info strong {
  color: var(--color-text);
}

/* 页脚 */
.site-footer {
  padding: 24px 20px;
  background: var(--color-text);
  color: #9ca3af;
  text-align: center;
  font-size: 0.9rem;
}

.site-footer p {
  margin: 0;
}

.site-footer .footer-icp {
  margin-top: 8px;
  font-size: 0.85rem;
}

.site-footer a {
  color: #93c5fd;
}