/* ===== CSS Variables ===== */
:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #3b82f6;
  --color-accent: #06b6d4;

  --bg-body: #ffffff;
  --bg-alt: #f8fafc;
  --bg-card: #ffffff;
  --bg-header: rgba(255, 255, 255, 0.95);

  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;

  --border-color: #e2e8f0;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.1);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;

  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --container: 1200px;
}

[data-theme="dark"] {
  --bg-body: #0f172a;
  --bg-alt: #1e293b;
  --bg-card: #1e293b;
  --bg-header: rgba(15, 23, 42, 0.95);

  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --border-color: #334155;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.4);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

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

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

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

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 100px 0;
}

.section-alt {
  background: var(--bg-alt);
}

/* ===== Section Header ===== */
.section-header {
  text-align: center;
  margin-bottom: 60px;
}

.section-title {
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 12px;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: '';
  display: block;
  width: 50px;
  height: 4px;
  background: var(--color-primary);
  margin: 16px auto 0;
  border-radius: 2px;
}

.section-subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  margin-top: 16px;
}

/* ===== Header ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: var(--bg-header);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  transition: background var(--transition), box-shadow var(--transition);
}

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

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

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: 1px;
}

.logo-img {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  flex-shrink: 0;
  background: url("../images/logo.png") center/contain no-repeat;
}

.logo-text {
  color: var(--color-primary);
}

.nav-list {
  display: flex;
  gap: 8px;
}

.nav-link {
  padding: 8px 16px;
  font-size: 0.95rem;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
  position: relative;
}

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

.nav-link.active {
  background: rgba(37, 99, 235, 0.08);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.theme-toggle,
.lang-toggle {
  background: none;
  border: 1px solid var(--border-color);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color var(--transition), background var(--transition);
  color: var(--text-primary);
}

.theme-toggle:hover,
.lang-toggle:hover {
  background: var(--bg-alt);
}

.theme-toggle {
  font-size: 1.1rem;
}

.lang-toggle {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.5px;
}

[data-theme="light"] .theme-icon-dark { display: none; }
[data-theme="dark"] .theme-icon-light { display: none; }

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition);
}

.hamburger.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.hamburger.open span:nth-child(2) {
  opacity: 0;
}
.hamburger.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ===== Hero Section ===== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  overflow: hidden;
  background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 50%, #e0f2fe 100%);
}

[data-theme="dark"] .hero {
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #0f172a 100%);
}

.hero-bg {
  position: absolute;
  inset: 0;
  overflow: hidden;
}

.hero-shape {
  position: absolute;
  border-radius: 50%;
  opacity: 0.15;
}

.hero-shape-1 {
  width: 600px;
  height: 600px;
  background: var(--color-primary);
  top: -200px;
  right: -100px;
  animation: float1 8s ease-in-out infinite;
}

.hero-shape-2 {
  width: 400px;
  height: 400px;
  background: var(--color-accent);
  bottom: -100px;
  left: -50px;
  animation: float2 10s ease-in-out infinite;
}

.hero-shape-3 {
  width: 300px;
  height: 300px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  animation: float3 12s ease-in-out infinite;
}

@keyframes float1 {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  50% { transform: translate(30px, -30px) rotate(5deg); }
}

@keyframes float2 {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  50% { transform: translate(-30px, 30px) rotate(-5deg); }
}

@keyframes float3 {
  0%, 100% { transform: translate(-50%, -50%) scale(1); }
  50% { transform: translate(-50%, -50%) scale(1.1); }
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero-subtitle {
  font-size: 0.85rem;
  letter-spacing: 4px;
  color: var(--color-primary);
  margin-bottom: 20px;
  font-weight: 500;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 16px;
  letter-spacing: 2px;
}

.hero-desc {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 40px;
  line-height: 1.8;
}

.hero-btns {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 36px;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  border: 2px solid transparent;
  letter-spacing: 0.5px;
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(37, 99, 235, 0.3);
}

.btn-outline {
  background: transparent;
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn-outline:hover {
  background: var(--color-primary);
  color: #fff;
  transform: translateY(-2px);
}

.btn-block {
  width: 100%;
}

/* ===== Scroll Indicator ===== */
.scroll-indicator {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  animation: bounce 2s ease-in-out infinite;
}

.scroll-arrow {
  display: block;
  width: 24px;
  height: 24px;
  border-right: 2px solid var(--text-muted);
  border-bottom: 2px solid var(--text-muted);
  transform: rotate(45deg);
}

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

/* ===== About Section ===== */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
  margin-bottom: 80px;
}

.about-text p {
  color: var(--text-secondary);
  margin-bottom: 16px;
  font-size: 1.05rem;
}

.about-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.stat-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px 24px;
  text-align: center;
  transition: transform var(--transition), box-shadow var(--transition);
}

.stat-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.stat-number {
  display: block;
  font-size: 2rem;
  font-weight: 800;
  color: var(--color-primary);
  margin-bottom: 4px;
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* Values */
.values-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.value-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 36px 24px;
  text-align: center;
  transition: transform var(--transition), box-shadow var(--transition);
}

.value-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.value-icon {
  font-size: 2.5rem;
  margin-bottom: 16px;
}

.value-card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.value-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ===== Services Section ===== */
.services-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.service-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 40px 28px;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  position: relative;
  overflow: hidden;
  text-align: center;
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--transition);
}

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

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

.service-icon {
  width: 56px;
  height: 56px;
  margin: 0 auto 20px;
  color: var(--color-primary);
}

.service-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.service-card p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ===== Cases Section ===== */
.cases-carousel {
  position: relative;
  overflow: hidden;
}

.cases-track {
  display: flex;
  gap: 24px;
  transition: transform 0.5s ease;
}

.case-card {
  flex: 0 0 calc((100% - 48px) / 3);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  transition: box-shadow var(--transition);
  user-select: none;
}

.case-card:hover {
  box-shadow: var(--shadow-md);
}

.case-tag {
  display: inline-block;
  padding: 4px 14px;
  background: rgba(37, 99, 235, 0.08);
  color: var(--color-primary);
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: 20px;
  margin-bottom: 16px;
}

.case-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.case-card > p {
  font-size: 0.93rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
}

.case-techs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.case-techs li {
  font-size: 0.8rem;
  padding: 4px 10px;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  color: var(--text-muted);
}

/* Cases Carousel - Dots */
.cases-dots {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin-top: 28px;
  margin-bottom: 16px;
}

.cases-dot {
  width: 10px;
  height: 10px;
  border: none;
  border-radius: 50%;
  background: var(--border-color);
  cursor: pointer;
  transition: background var(--transition), transform var(--transition);
  padding: 0;
}

.cases-dot.active {
  background: var(--color-primary);
  transform: scale(1.3);
}

/* Cases Carousel - Arrows */
.cases-arrow {
  position: absolute;
  top: calc(50% - 28px);
  z-index: 10;
  width: 40px;
  height: 40px;
  border: 1px solid var(--border-color);
  border-radius: 50%;
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--transition), box-shadow var(--transition), transform var(--transition), border-color var(--transition);
  box-shadow: var(--shadow-sm);
}

.cases-arrow svg {
  width: 18px;
  height: 18px;
}

.cases-carousel:hover .cases-arrow {
  opacity: 1;
}

.cases-arrow:hover {
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.18);
  border-color: var(--color-primary);
  transform: scale(1.08);
}

.cases-arrow-prev {
  left: 12px;
}

.cases-arrow-next {
  right: 12px;
}

@media (max-width: 1024px) {
  .case-card {
    flex: 0 0 calc((100% - 24px) / 2);
  }
}

@media (max-width: 768px) {
  .case-card {
    flex: 0 0 100%;
  }

  .cases-arrow {
    display: none;
  }
}

/* ===== Contact Section ===== */
.contact-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 60px;
  align-items: stretch;
}

.contact-form {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 40px;
  height: 100%;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--bg-body);
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-group input.error,
.form-group textarea.error {
  border-color: #ef4444;
}

.form-error-msg {
  font-size: 0.82rem;
  color: #ef4444;
  margin-top: 4px;
  display: none;
}

.form-error-msg.show {
  display: block;
}

.form-success {
  text-align: center;
  padding: 40px 20px;
}

.form-success-icon {
  width: 64px;
  height: 64px;
  background: #10b981;
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
  margin: 0 auto 20px;
}

.form-success h3 {
  font-size: 1.3rem;
  margin-bottom: 8px;
}

.form-success p {
  color: var(--text-secondary);
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.contact-info-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px;
}

.contact-info-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.contact-item {
  display: flex;
  gap: 16px;
  margin-bottom: 20px;
  align-items: flex-start;
}

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

.contact-icon {
  font-size: 1.3rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.contact-item strong {
  display: block;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 2px;
}

.contact-item p {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

.contact-qr {
  text-align: center;
}

.qr-placeholder {
  width: 120px;
  height: 120px;
  margin: 0 auto 16px;
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  background: url('../images/qrcode_wechat.jpg') center/contain no-repeat;
}

/* ===== Footer ===== */
.footer {
  background: var(--bg-alt);
  border-top: 1px solid var(--border-color);
}

.footer-inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 60px;
  padding: 60px 24px 40px;
}

.footer-brand p {
  margin-top: 12px;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.footer-logo {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-primary);
}

.footer-links h4 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 16px;
}

.footer-links ul {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-links li,
.footer-links a {
  font-size: 0.93rem;
  color: var(--text-secondary);
  transition: color var(--transition);
}

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

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding: 20px 0;
  text-align: center;
}

.footer-bottom p {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ===== Back to Top ===== */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  z-index: 999;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: none;
  background: var(--color-primary);
  color: #fff;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 16px rgba(37, 99, 235, 0.3);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: all var(--transition);
}

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

.back-to-top:hover {
  background: var(--color-primary-dark);
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(37, 99, 235, 0.4);
}

/* ===== Scroll Reveal Animations ===== */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered delays for grid children */
.values-grid .value-card:nth-child(1) { transition-delay: 0s; }
.values-grid .value-card:nth-child(2) { transition-delay: 0.1s; }
.values-grid .value-card:nth-child(3) { transition-delay: 0.2s; }
.values-grid .value-card:nth-child(4) { transition-delay: 0.3s; }

.services-grid .service-card:nth-child(1) { transition-delay: 0s; }
.services-grid .service-card:nth-child(2) { transition-delay: 0.1s; }
.services-grid .service-card:nth-child(3) { transition-delay: 0.2s; }
.services-grid .service-card:nth-child(4) { transition-delay: 0.3s; }

/* ===== Responsive - Tablet ===== */
@media (max-width: 1024px) {
  .about-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

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

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

  .contact-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .footer-inner {
    grid-template-columns: 1fr 1fr;
    gap: 40px;
  }
}

/* ===== Responsive - Mobile ===== */
@media (max-width: 768px) {
  .section {
    padding: 70px 0;
  }

  .section-title {
    font-size: 1.8rem;
  }

  .hamburger {
    display: flex;
  }

  .nav {
    position: fixed;
    top: 72px;
    left: 0;
    width: 100%;
    background: var(--bg-header);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    padding: 16px 0;
    transform: translateY(-110%);
    opacity: 0;
    transition: transform var(--transition), opacity var(--transition);
    z-index: -1;
  }

  .nav.open {
    transform: translateY(0);
    opacity: 1;
    z-index: 999;
  }

  .nav-list {
    flex-direction: column;
    gap: 4px;
    padding: 0 24px;
  }

  .nav-link {
    display: block;
    padding: 12px 16px;
    font-size: 1.05rem;
  }

  .hero-title {
    font-size: 2.2rem;
  }

  .hero-desc {
    font-size: 1rem;
  }

  .hero-subtitle {
    font-size: 0.75rem;
    letter-spacing: 3px;
  }

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

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

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

  .contact-form {
    padding: 24px;
  }

  .contact-info-card {
    padding: 24px;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: 32px;
    text-align: center;
  }

  .footer-links ul {
    align-items: center;
  }

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

@media (max-width: 480px) {
  .hero-title {
    font-size: 1.8rem;
  }

  .hero-btns {
    flex-direction: column;
    align-items: center;
  }

  .hero-btns .btn {
    width: 200px;
  }

  .about-stats {
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }

  .stat-item {
    padding: 20px 16px;
  }

  .stat-number {
    font-size: 1.6rem;
  }
}