/* =============================================
   CSS Custom Properties — Yangtze Brand Colors
   Primary: deep navy blue extracted from logo
   ============================================= */
:root {
  --primary:        #1c3d7a;
  --primary-dark:   #112850;
  --primary-light:  #2e5fa3;
  --primary-xlight: #e8eef8;
  --accent:         #2d8a3e;
  --accent-dark:    #1e6128;
  --accent-light:   #e6f4ea;
  --silver:         #8a9ba8;

  --text:           #1a2233;
  --text-muted:     #5a6a7e;
  --background:     #ffffff;
  --section-bg:     #f4f7fc;
  --border:         #dde4ef;

  --radius:         12px;
  --radius-sm:      8px;
  --shadow-sm:      0 2px 8px rgba(28,61,122,0.08);
  --shadow-md:      0 6px 24px rgba(28,61,122,0.12);
  --shadow-lg:      0 16px 48px rgba(28,61,122,0.16);

  --font:           'Inter', system-ui, -apple-system, sans-serif;
  --max-w:          1200px;
  --header-h:       72px;
  --transition:     0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== RESET ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font);
  color: var(--text);
  background: var(--background);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
address { font-style: normal; }
svg { display: block; }
button { cursor: pointer; font-family: var(--font); border: none; background: none; }

/* ===== UTILITY ===== */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 96px 0;
}
.section-alt {
  background: var(--section-bg);
}

.eyebrow {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 12px;
}

.section-title {
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  font-weight: 700;
  color: var(--primary-dark);
  line-height: 1.2;
  margin-bottom: 16px;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.7;
}

.section-header {
  text-align: center;
  margin-bottom: 56px;
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 32px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  transition: var(--transition);
  white-space: nowrap;
}
.btn-primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 16px rgba(28,61,122,0.25);
}
.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(28,61,122,0.32);
}
.btn-ghost {
  background: rgba(255,255,255,0.12);
  color: #fff;
  border: 1.5px solid rgba(255,255,255,0.4);
  backdrop-filter: blur(4px);
}
.btn-ghost:hover {
  background: rgba(255,255,255,0.22);
  border-color: rgba(255,255,255,0.7);
  transform: translateY(-2px);
}

/* ===== REVEAL ANIMATIONS ===== */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== HEADER ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-h);
  background: transparent;
  transition: background var(--transition), box-shadow var(--transition);
}
.site-header.scrolled {
  background: var(--primary-dark);
  box-shadow: 0 2px 16px rgba(17,40,80,0.3);
}
.header-inner {
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.logo-link { flex-shrink: 0; }
.logo-img {
  height: 44px;
  width: auto;
  transition: opacity var(--transition);
}
.logo-img:hover { opacity: 0.85; }

.nav-list {
  display: flex;
  align-items: center;
  gap: 8px;
}
.nav-link {
  display: block;
  padding: 8px 14px;
  font-size: 0.875rem;
  font-weight: 500;
  color: rgba(255,255,255,0.88);
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
}
.nav-link:hover,
.nav-link.active {
  color: #fff;
  background: rgba(255,255,255,0.12);
}

.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 8px;
  border-radius: var(--radius-sm);
  transition: background var(--transition);
}
.hamburger:hover { background: rgba(255,255,255,0.12); }
.hamburger span {
  display: block;
  height: 2px;
  background: #fff;
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition), width var(--transition);
  transform-origin: center;
}
.hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ===== HERO ===== */
.hero {
  position: relative;
  min-height: 100vh;
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 60%, #1e5a8a 100%);
  display: flex;
  align-items: center;
  overflow: hidden;
}
.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.hero-shape {
  position: absolute;
  color: rgba(255,255,255,0.06);
}
.hero-shape.s1 {
  width: 340px;
  height: 390px;
  top: 8%;
  right: 8%;
  animation: float 12s ease-in-out infinite;
}
.hero-shape.s2 {
  width: 240px;
  height: 240px;
  bottom: 12%;
  right: 20%;
  animation: float 16s ease-in-out infinite reverse;
}
.hero-ring {
  position: absolute;
  border-radius: 50%;
  border: 1px solid rgba(255,255,255,0.06);
}
.hero-ring.r1 {
  width: 500px; height: 500px;
  top: -100px; left: -100px;
  animation: float 20s ease-in-out infinite;
}
.hero-ring.r2 {
  width: 320px; height: 320px;
  bottom: -60px; right: 5%;
  animation: float 14s ease-in-out infinite reverse;
}
.hero-ring.r3 {
  width: 180px; height: 180px;
  top: 30%; left: 5%;
  animation: float 18s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  33%       { transform: translate(10px, -14px) rotate(2deg); }
  66%       { transform: translate(-6px, 8px) rotate(-1deg); }
}

.hero-content {
  position: relative;
  z-index: 2;
  padding-top: var(--header-h);
  text-align: center;
}
.hero-eyebrow {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.7);
  background: rgba(255,255,255,0.1);
  border: 1px solid rgba(255,255,255,0.2);
  padding: 6px 16px;
  border-radius: 100px;
  margin-bottom: 24px;
}
.hero-headline {
  font-size: clamp(2.2rem, 5vw, 3.75rem);
  font-weight: 700;
  color: #fff;
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin-bottom: 24px;
}
.hero-sub {
  font-size: clamp(1rem, 1.5vw, 1.2rem);
  color: rgba(255,255,255,0.78);
  max-width: 600px;
  margin: 0 auto 40px;
  line-height: 1.7;
}
.hero-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}
.hero-scroll {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
}
.scroll-line {
  width: 1.5px;
  height: 48px;
  background: linear-gradient(to bottom, rgba(255,255,255,0.6), transparent);
  margin: 0 auto;
  animation: scroll-pulse 2s ease-in-out infinite;
}
@keyframes scroll-pulse {
  0%, 100% { opacity: 0.6; transform: scaleY(1); }
  50%       { opacity: 1;   transform: scaleY(0.7); }
}

/* ===== ABOUT ===== */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 72px;
  align-items: start;
}
.about-text p {
  color: var(--text-muted);
  line-height: 1.75;
  margin-bottom: 16px;
  font-size: 1rem;
}
.about-text p strong { color: var(--primary); }
.stats-row {
  display: flex;
  gap: 32px;
  margin-top: 40px;
  padding-top: 32px;
  border-top: 1px solid var(--border);
}
.stat { text-align: left; }
.stat-num {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary);
  line-height: 1;
  margin-bottom: 4px;
}
.stat-label {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.about-features {
  display: flex;
  flex-direction: column;
  gap: 0;
}
.feature-item {
  display: flex;
  gap: 20px;
  align-items: flex-start;
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
}
.feature-item:last-child { border-bottom: none; }
.feature-icon {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: var(--primary-xlight);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  transition: background var(--transition), color var(--transition);
}
.feature-icon svg { width: 20px; height: 20px; }
.feature-item:hover .feature-icon {
  background: var(--primary);
  color: #fff;
}
.feature-item h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--primary-dark);
  margin-bottom: 4px;
}
.feature-item p {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* ===== PRODUCTS ===== */
.products-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.product-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 36px 28px;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}
.product-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
}
.pcard-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-sm);
  background: var(--primary-xlight);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  margin-bottom: 20px;
  transition: background var(--transition), color var(--transition);
}
.pcard-icon svg { width: 24px; height: 24px; }
.product-card:hover .pcard-icon {
  background: var(--primary);
  color: #fff;
}
.product-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--primary-dark);
  margin-bottom: 10px;
}
.product-card p {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ===== INDUSTRIES ===== */
.industries-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
.industry-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 20px;
  text-align: center;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition), background var(--transition);
  cursor: default;
}
.industry-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-sm);
  border-color: var(--primary-light);
  background: var(--primary-xlight);
}
.ind-icon {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: var(--primary-xlight);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  margin: 0 auto 14px;
  transition: background var(--transition), color var(--transition);
}
.ind-icon svg { width: 22px; height: 22px; }
.industry-card:hover .ind-icon {
  background: var(--primary);
  color: #fff;
}
.industry-card span {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--primary-dark);
  line-height: 1.3;
}

/* ===== PROCESS ===== */
.process-track {
  position: relative;
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 0;
}
.process-line {
  position: absolute;
  top: 40px;
  left: calc(100% / 14);
  right: calc(100% / 14);
  height: 2px;
  background: linear-gradient(to right, var(--primary-xlight), var(--primary-light), var(--primary-xlight));
  z-index: 0;
}
.process-step {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 0 8px;
}
.ps-icon {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: #fff;
  border: 2px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  margin: 0 auto 14px;
  transition: background var(--transition), border-color var(--transition), color var(--transition), box-shadow var(--transition);
  box-shadow: var(--shadow-sm);
}
.ps-icon svg { width: 22px; height: 22px; }
.ps-icon--accent {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.process-step:hover .ps-icon {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  box-shadow: var(--shadow-md);
}
.process-step:hover .ps-icon--accent {
  background: var(--accent-dark);
  border-color: var(--accent-dark);
}
.ps-num {
  display: block;
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--primary-light);
  letter-spacing: 0.08em;
  margin-bottom: 6px;
}
.process-step h4 {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--primary-dark);
  margin-bottom: 6px;
}
.process-step p {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* ===== CONTACT ===== */
.contact-section {
  background: linear-gradient(160deg, var(--primary-dark) 0%, var(--primary) 100%);
}
.contact-section .eyebrow { color: rgba(255,255,255,0.7); }
.contact-section .section-title { color: #fff; }
.contact-section .section-desc { color: rgba(255,255,255,0.72); }

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 20px;
}
.contact-card {
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.16);
  border-radius: var(--radius);
  padding: 32px 28px;
  display: flex;
  align-items: flex-start;
  gap: 20px;
  transition: background var(--transition), transform var(--transition);
  backdrop-filter: blur(8px);
}
.contact-card:hover {
  background: rgba(255,255,255,0.14);
  transform: translateY(-4px);
}
.contact-card--wide {
  grid-column: span 1;
}
.contact-icon {
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background: rgba(255,255,255,0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
}
.contact-icon svg { width: 22px; height: 22px; }
.contact-info h4 {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: rgba(255,255,255,0.6);
  margin-bottom: 8px;
}
.contact-info a,
.contact-info address {
  font-size: 0.95rem;
  color: #fff;
  line-height: 1.6;
}
.contact-info a:hover { text-decoration: underline; opacity: 0.9; }

/* ===== FOOTER ===== */
.site-footer {
  background: var(--primary-dark);
  color: rgba(255,255,255,0.75);
  border-top: 1px solid rgba(255,255,255,0.06);
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1.5fr;
  gap: 56px;
  padding-top: 64px;
  padding-bottom: 48px;
}
.footer-brand .footer-logo {
  height: 36px;
  opacity: 0.9;
  margin-bottom: 20px;
}
.footer-brand p {
  font-size: 0.875rem;
  line-height: 1.7;
  max-width: 320px;
}
.footer-col h5 {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: #fff;
  margin-bottom: 20px;
}
.footer-col ul li {
  margin-bottom: 10px;
}
.footer-col ul li a {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.65);
  transition: color var(--transition);
}
.footer-col ul li a:hover { color: #fff; }
.footer-contact-list li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 0.875rem;
  color: rgba(255,255,255,0.65);
  line-height: 1.5;
}
.footer-contact-list svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
  margin-top: 2px;
  color: rgba(255,255,255,0.45);
}
.footer-contact-list a {
  color: rgba(255,255,255,0.65);
  transition: color var(--transition);
}
.footer-contact-list a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.08);
  padding: 20px 0;
}
.footer-bottom p {
  font-size: 0.8rem;
  color: rgba(255,255,255,0.4);
  text-align: center;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 1024px) {
  .products-grid { grid-template-columns: repeat(2, 1fr); }
  .industries-grid { grid-template-columns: repeat(4, 1fr); }
  .about-grid { grid-template-columns: 1fr; gap: 48px; }
  .process-track {
    grid-template-columns: repeat(4, 1fr);
    gap: 24px 0;
  }
  .process-line { display: none; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 40px; }
  .footer-brand { grid-column: span 2; }
}

@media (max-width: 768px) {
  :root { --header-h: 64px; }
  .section { padding: 72px 0; }

  .hamburger { display: flex; }
  .main-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    background: var(--primary-dark);
    padding: 16px 24px 24px;
    transform: translateY(-8px);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--transition), opacity var(--transition);
    box-shadow: var(--shadow-lg);
  }
  .main-nav.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  .nav-list { flex-direction: column; gap: 4px; }
  .nav-link { padding: 12px 16px; font-size: 0.95rem; }

  .hero-headline { font-size: clamp(1.75rem, 6vw, 2.5rem); }
  .hero-cta { flex-direction: column; align-items: center; }

  .about-grid { gap: 40px; }
  .stats-row { gap: 20px; }
  .stat-num { font-size: 1.5rem; }

  .products-grid { grid-template-columns: 1fr; gap: 16px; }
  .industries-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }

  .process-track {
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
  }

  .contact-grid { grid-template-columns: 1fr; gap: 16px; }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
    padding-top: 48px;
    padding-bottom: 32px;
  }
  .footer-brand { grid-column: span 1; }
}

@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .industries-grid { grid-template-columns: repeat(2, 1fr); }
  .process-track { grid-template-columns: 1fr 1fr; }
  .stats-row { flex-wrap: wrap; gap: 16px; }
}