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

:root {
  --primary: #1a6fc4;
  --primary-dark: #145a9e;
  --primary-deeper: #0d4a82;
  --primary-light: #e8f1fc;
  --primary-lighter: #f0f7ff;
  --accent: #f5851f;
  --accent-hover: #e07510;
  --dark: #1a2332;
  --gray-900: #1f2937;
  --gray-800: #2d3748;
  --gray-700: #4a5568;
  --gray-600: #5a6577;
  --gray-500: #6b7280;
  --gray-400: #9ca3af;
  --gray-300: #d1d5db;
  --gray-200: #e5e7eb;
  --gray-100: #f3f4f6;
  --gray-50: #f9fafb;
  --white: #ffffff;
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
  --shadow-md: 0 8px 32px rgba(0,0,0,0.1);
  --shadow-lg: 0 12px 48px rgba(0,0,0,0.12);
  --radius: 12px;
  --radius-lg: 16px;
  --transition: all 0.3s ease;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--gray-700);
  line-height: 1.7;
  background: var(--white);
  overflow-x: hidden;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

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

img { max-width: 100%; }

/* ===== Header ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: transparent;
  transition: all 0.4s ease;
  border-bottom: 1px solid transparent;
}

.header.scrolled {
  background: rgba(26, 35, 50, 0.97);
  backdrop-filter: blur(20px);
  border-bottom-color: rgba(255,255,255,0.08);
  box-shadow: 0 4px 30px rgba(0,0,0,0.15);
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo-svg {
  width: 40px;
  height: 40px;
}

.logo-text {
  font-size: 20px;
  font-weight: 700;
  color: var(--white);
}

.header.scrolled .logo-text {
  color: var(--white);
}

.nav {
  display: flex;
  gap: 32px;
}

.nav-link {
  font-size: 15px;
  color: rgba(255,255,255,0.85);
  font-weight: 500;
  position: relative;
  padding: 4px 0;
  letter-spacing: 0.3px;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: var(--transition);
  transform: translateX(-50%);
}

.nav-link:hover,
.nav-link.active {
  color: var(--accent);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 24px;
  color: var(--white);
  cursor: pointer;
}

/* ===== Hero / Banner ===== */
.hero {
  position: relative;
  height: 100vh;
  min-height: 600px;
  overflow: hidden;
}

.hero-slides {
  position: absolute;
  inset: 0;
  z-index: 1;
}

.hero-slide {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 1.2s ease;
  background-size: cover;
  background-position: center;
}

.hero-slide.active {
  opacity: 1;
}

.hero-slide::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(22, 74, 140, 0.82) 0%, rgba(26, 111, 196, 0.55) 50%, rgba(13, 74, 130, 0.75) 100%);
}

.hero-slide:nth-child(2)::after {
  background: linear-gradient(135deg, rgba(13, 74, 130, 0.85) 0%, rgba(20, 90, 158, 0.5) 50%, rgba(26, 111, 196, 0.7) 100%);
}

.hero-slide:nth-child(3)::after {
  background: linear-gradient(135deg, rgba(26, 111, 196, 0.75) 0%, rgba(13, 74, 130, 0.6) 50%, rgba(20, 90, 158, 0.8) 100%);
}

.hero-content {
  position: relative;
  z-index: 2;
  color: var(--white);
  padding: 0 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  text-align: center;
}

.hero-tag {
  display: inline-block;
  padding: 6px 20px;
  background: rgba(255,255,255,0.15);
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 50px;
  font-size: 14px;
  color: rgba(255,255,255,0.9);
  margin-bottom: 24px;
  backdrop-filter: blur(10px);
  letter-spacing: 1px;
}

.hero-title {
  font-size: clamp(32px, 5vw, 52px);
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 20px;
  letter-spacing: -0.5px;
  text-shadow: 0 2px 20px rgba(0,0,0,0.15);
}

.hero-subtitle {
  font-size: clamp(15px, 2vw, 18px);
  color: rgba(255,255,255,0.8);
  max-width: 580px;
  margin: 0 auto 40px;
  line-height: 1.7;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 56px;
  margin-bottom: 44px;
  flex-wrap: wrap;
}

.stat-item {
  text-align: center;
}

.stat-num {
  font-size: 44px;
  font-weight: 800;
  color: var(--white);
  display: inline;
  letter-spacing: -1px;
}

.stat-plus {
  font-size: 22px;
  font-weight: 700;
  color: var(--accent);
}

.stat-label {
  display: block;
  font-size: 14px;
  color: rgba(255,255,255,0.6);
  margin-top: 4px;
}

.btn-primary {
  display: inline-block;
  padding: 14px 40px;
  background: var(--accent);
  color: var(--white);
  font-size: 16px;
  font-weight: 600;
  border: none;
  border-radius: 50px;
  cursor: pointer;
  transition: var(--transition);
  letter-spacing: 0.5px;
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(245, 133, 31, 0.4);
}

/* Banner Dots */
.hero-dots {
  position: absolute;
  bottom: 80px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 3;
  display: flex;
  gap: 10px;
}

.hero-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: rgba(255,255,255,0.35);
  border: 2px solid rgba(255,255,255,0.5);
  cursor: pointer;
  transition: var(--transition);
}

.hero-dot.active {
  background: var(--accent);
  border-color: var(--accent);
  transform: scale(1.15);
}

.hero-scroll {
  position: absolute;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 3;
  color: rgba(255,255,255,0.45);
  font-size: 18px;
  animation: bounce 2s infinite;
}

@keyframes bounce {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(10px); }
}

/* Banner Arrows */
.hero-arrow {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  z-index: 3;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: rgba(255,255,255,0.1);
  border: 1px solid rgba(255,255,255,0.2);
  color: var(--white);
  font-size: 18px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  backdrop-filter: blur(5px);
}

.hero-arrow:hover {
  background: rgba(255,255,255,0.2);
  border-color: rgba(255,255,255,0.35);
}

.hero-arrow.prev { left: 30px; }
.hero-arrow.next { right: 30px; }

/* ===== Sections ===== */
.section {
  padding: 100px 0;
}

.section-header {
  text-align: center;
  margin-bottom: 60px;
}

.section-title {
  font-size: 36px;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 16px;
  position: relative;
}

.section-title.left {
  text-align: left;
}

.section-title::after {
  content: '';
  display: block;
  width: 48px;
  height: 3px;
  background: var(--accent);
  margin: 14px auto 0;
  border-radius: 2px;
}

.section-title.left::after {
  margin-left: 0;
}

.section-desc {
  font-size: 16px;
  color: var(--gray-500);
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.7;
}

/* ===== Services ===== */
.services {
  background: var(--gray-50);
}

.services-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.service-card {
  background: var(--white);
  padding: 40px 32px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  text-align: center;
  position: relative;
  overflow: hidden;
  border: 1px solid var(--gray-200);
}

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

.service-icon {
  width: 72px;
  height: 72px;
  margin: 0 auto 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--primary-light);
  border-radius: 16px;
  font-size: 28px;
  color: var(--primary);
  transition: var(--transition);
}

.service-card:hover .service-icon {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--white);
  transform: scale(1.08);
}

.service-card h3 {
  font-size: 19px;
  color: var(--gray-800);
  margin-bottom: 12px;
  font-weight: 600;
}

.service-card p {
  font-size: 14px;
  color: var(--gray-600);
  line-height: 1.8;
}

.service-card:hover p {
  color: var(--gray-700);
}

/* ===== About ===== */
.about-wrap {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.about-img {
  width: 100%;
  height: 400px;
  object-fit: cover;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.about-content p {
  margin-bottom: 16px;
  font-size: 15px;
  color: var(--gray-600);
  line-height: 1.8;
}

.about-features {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 24px;
}

.feature-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 15px;
  font-weight: 500;
  color: var(--gray-800);
}

.feature-item i {
  color: var(--accent);
  font-size: 18px;
}

/* ===== Cases ===== */
.cases {
  background: var(--gray-50);
}

.cases-filter {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-bottom: 40px;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 8px 24px;
  border: 2px solid var(--gray-300);
  background: var(--white);
  border-radius: 50px;
  font-size: 14px;
  color: var(--gray-600);
  cursor: pointer;
  transition: var(--transition);
  font-weight: 500;
}

.filter-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.filter-btn.active {
  border-color: var(--primary);
  color: var(--white);
  background: var(--primary);
}

.cases-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.case-card {
  background: var(--white);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  border: 1px solid var(--gray-200);
}

.case-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: transparent;
}

.case-card.hidden {
  display: none;
}

.case-img {
  height: 200px;
  background: linear-gradient(135deg, var(--primary-light), var(--gray-200));
  background-size: cover;
  background-position: center;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 48px;
  color: var(--primary);
  transition: transform 0.5s ease;
}

.case-card:hover .case-img {
  transform: scale(1.05);
}

.case-info {
  padding: 24px;
}

.case-info h4 {
  font-size: 18px;
  color: var(--dark);
  margin-bottom: 8px;
  font-weight: 600;
}

.case-info p {
  font-size: 14px;
  color: var(--gray-600);
  line-height: 1.6;
  margin-bottom: 12px;
}

.case-tag {
  display: inline-block;
  padding: 4px 14px;
  background: var(--primary-light);
  color: var(--primary-dark);
  font-size: 12px;
  border-radius: 20px;
  font-weight: 500;
}

/* ===== Process ===== */
.process {
  background: var(--gray-50);
  position: relative;
}

.process .section-title {
  color: var(--gray-900);
}

.process .section-desc {
  color: var(--gray-500);
}

.process .section-title::after {
  background: var(--accent);
}

.process-steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.step {
  text-align: center;
  position: relative;
  padding: 32px 24px;
}

.step-num {
  font-size: 48px;
  font-weight: 800;
  color: rgba(26, 111, 196, 0.08);
  line-height: 1;
  margin-bottom: 16px;
}

.step-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--white);
  border-radius: 50%;
  font-size: 24px;
  box-shadow: 0 4px 20px rgba(26, 111, 196, 0.3);
  transition: var(--transition);
}

.step:hover .step-icon {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px rgba(26, 111, 196, 0.45);
}

.step h4 {
  font-size: 18px;
  color: var(--gray-900);
  margin-bottom: 8px;
  font-weight: 600;
}

.step p {
  font-size: 14px;
  color: var(--gray-500);
  line-height: 1.6;
}

/* ===== Footer ===== */
.footer {
  background: linear-gradient(135deg, var(--dark) 0%, #1a3045 100%);
  color: rgba(255,255,255,0.7);
  padding: 60px 0 0;
}

.footer-top {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255,255,255,0.08);
}

.footer-brand p {
  margin-top: 16px;
  font-size: 14px;
  line-height: 1.8;
  color: rgba(255,255,255,0.5);
}

.footer-brand .logo-text {
  color: var(--white);
}

.footer-links h4 {
  color: var(--white);
  font-size: 16px;
  margin-bottom: 16px;
  font-weight: 600;
}

.footer-links a {
  display: block;
  font-size: 14px;
  color: rgba(255,255,255,0.45);
  margin-bottom: 10px;
}

.footer-links a:hover {
  color: var(--accent);
}

.footer-links a i {
  margin-right: 8px;
}

.footer-bottom {
  text-align: center;
  padding: 24px 0;
  font-size: 13px;
  color: rgba(255,255,255,0.3);
}

.footer-bottom a {
  color: rgba(255,255,255,0.45);
}

.footer-bottom a:hover {
  color: var(--accent);
}

/* ===== Back to Top ===== */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 48px;
  height: 48px;
  background: var(--primary);
  color: var(--white);
  border: none;
  border-radius: 50%;
  font-size: 18px;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
  box-shadow: 0 4px 16px rgba(26, 111, 196, 0.3);
  z-index: 999;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

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

/* ===== Animations ===== */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .services-grid,
  .cases-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

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

@media (max-width: 768px) {
  .header {
    background: rgba(26, 35, 50, 0.95);
  }

  .nav {
    display: none;
    position: absolute;
    top: 72px;
    left: 0;
    width: 100%;
    background: rgba(26, 35, 50, 0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 20px;
    gap: 0;
    box-shadow: 0 8px 30px rgba(0,0,0,0.2);
  }

  .nav.open {
    display: flex;
  }

  .nav-link {
    padding: 12px 0;
    border-bottom: 1px solid rgba(255,255,255,0.08);
    color: rgba(255,255,255,0.8);
  }

  .menu-toggle {
    display: block;
  }

  .hero-stats {
    gap: 24px;
  }

  .stat-num {
    font-size: 32px;
  }

  .hero-arrow { display: none; }

  .services-grid,
  .cases-grid,
  .process-steps {
    grid-template-columns: 1fr;
  }

  .about-wrap {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .about-img {
    height: 260px;
  }

  .footer-top {
    grid-template-columns: 1fr;
  }

  .section {
    padding: 60px 0;
  }

  .section-title {
    font-size: 28px;
  }
}