/* ================================================================
   海联智达 AI数字员工 — 布局系统
   Nav / Grid / Footer / Responsive Utilities
   ================================================================ */

/* ── 导航栏 ── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: oklch(0.99 0.001 250 / 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  transition: background var(--normal), box-shadow var(--normal);
}

.nav.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  max-width: var(--container-2xl);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
  color: var(--text-primary);
}

.nav-brand .brand-icon {
  width: 36px;
  height: 36px;
  background: var(--primary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: var(--font-bold);
  font-size: var(--text-sm);
}

.nav-brand .brand-text {
  font-family: var(--font-heading);
  font-weight: var(--font-bold);
  font-size: var(--text-lg);
}

.nav-brand .brand-text span {
  color: var(--primary);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-8);
}

.nav-links a {
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--text-secondary);
  text-decoration: none;
  transition: color var(--fast);
}

.nav-links a:hover {
  color: var(--primary);
}

.nav-cta {
  font-size: var(--text-sm);
}

/* 汉堡菜单（移动端） */
.nav-burger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-2);
  cursor: pointer;
}

.nav-burger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 1px;
  transition: all var(--normal);
}

@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-burger { display: flex; }

  /* 展开状态 */
  .nav-open .nav-links {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: var(--space-6);
    gap: var(--space-5);
    box-shadow: var(--shadow-md);
  }
}

/* ── Hero区布局 ── */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 68px;
  position: relative;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-16);
  align-items: center;
}

@media (max-width: 1024px) {
  .hero-grid { grid-template-columns: 1fr; }
}

.hero-visual {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

@media (max-width: 1024px) {
  .hero-visual { display: none; }
}

/* ── 通用网格 ── */
.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-6);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-6);
}

@media (max-width: 1024px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

/* 两列对比布局 */
.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-10);
  align-items: start;
}

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

/* ── Footer ── */
.footer {
  background: var(--dark-bg);
  color: var(--dark-muted);
  padding: var(--space-16) 0 var(--space-8);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-10);
  margin-bottom: var(--space-12);
}

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

@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
}

.footer-brand {
  font-family: var(--font-heading);
  font-weight: var(--font-bold);
  font-size: var(--text-xl);
  color: white;
  margin-bottom: var(--space-4);
}

.footer-brand span { color: var(--cta); }

.footer-desc {
  font-size: var(--text-sm);
  line-height: var(--leading-loose);
  max-width: 320px;
}

.footer-title {
  font-weight: var(--font-semibold);
  color: white;
  font-size: var(--text-sm);
  margin-bottom: var(--space-4);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.footer-links a {
  font-size: var(--text-sm);
  color: var(--dark-muted);
  text-decoration: none;
  transition: color var(--fast);
}

.footer-links a:hover {
  color: white;
}

.footer-bottom {
  border-top: 1px solid var(--dark-border);
  padding-top: var(--space-8);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: var(--text-xs);
  color: oklch(0.45 0.01 250);
}

@media (max-width: 640px) {
  .footer-bottom { flex-direction: column; gap: var(--space-3); text-align: center; }
}

/* ── 移动端固定CTA ── */
.mobile-cta {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 900;
  padding: var(--space-3) var(--space-4);
  background: var(--surface);
  border-top: 1px solid var(--border);
  box-shadow: 0 -2px 12px oklch(0 0 0 / 0.06);
}

@media (max-width: 768px) {
  .mobile-cta { display: block; }
}

/* ── 响应式工具类 ── */
.hide-mobile  { }
.hide-desktop { display: none; }

@media (max-width: 768px) {
  .hide-mobile  { display: none !important; }
  .hide-desktop { display: block; }
}

/* ── 背景装饰 ── */
.bg-gradient-blue {
  background: linear-gradient(135deg, oklch(0.48 0.15 250) 0%, oklch(0.30 0.12 250) 100%);
}

.bg-dots {
  background-image: radial-gradient(circle, var(--border) 1px, transparent 1px);
  background-size: 24px 24px;
}

/* ── 粘性侧边栏 ── */
.sticky-top {
  position: sticky;
  top: 88px;
}