/* === CSS Variables === */
:root {
  --primary: #1a365d;
  --secondary: #3182ce;
  --accent: #38a169;
  --bg-white: #ffffff;
  --bg-light: #f7fafc;
  --text-body: #2d3748;
  --text-heading: #1a202c;
  --font-heading: 'Playfair Display', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --max-width: 1200px;
  --section-padding: 5rem 2rem;
  --card-radius: 8px;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
}

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

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

body {
  font-family: var(--font-body);
  color: var(--text-body);
  line-height: 1.7;
  background: var(--bg-white);
}

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  color: var(--text-heading);
  line-height: 1.3;
}

h1 { font-size: 3rem; }
h2 { font-size: 2.25rem; }
h3 { font-size: 1.5rem; }

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

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

.section-img {
  width: 100%;
  border-radius: var(--card-radius);
  box-shadow: var(--shadow);
  margin: 2rem auto 0;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem;
}

.container-wide {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 1rem;
}

section {
  padding: var(--section-padding);
}

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

/* === Navigation === */
#nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 1rem 2rem;
  transition: background 0.3s, box-shadow 0.3s;
}

#nav.scrolled {
  background: var(--bg-white);
  box-shadow: var(--shadow);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: #ffffff;
  transition: color 0.3s;
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.logo-tagline {
  font-family: var(--font-body);
  font-size: 0.65rem;
  font-weight: 400;
  letter-spacing: 0.05em;
  color: rgba(255, 255, 255, 0.7);
  white-space: nowrap;
}

#nav.scrolled .logo {
  color: var(--primary);
}

#nav.scrolled .logo-tagline {
  color: var(--text-body);
  opacity: 0.6;
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  color: rgba(255, 255, 255, 0.85);
  font-weight: 500;
  font-size: 0.95rem;
  transition: color 0.2s;
}

#nav.scrolled .nav-links a {
  color: var(--text-body);
}

.nav-links a:hover,
.nav-links a.active {
  color: #ffffff;
}

#nav.scrolled .nav-links a:hover,
#nav.scrolled .nav-links a.active {
  color: var(--secondary);
}

/* === Buttons === */
.btn {
  display: inline-block;
  padding: 0.75rem 1.75rem;
  border-radius: 6px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: background 0.2s, transform 0.2s;
}

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

.btn-primary:hover {
  background: var(--primary);
  transform: translateY(-1px);
}

.btn-lg {
  padding: 1rem 2.5rem;
  font-size: 1.1rem;
}

.nav-cta {
  display: inline-block;
}

/* === 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: #ffffff;
  transition: transform 0.3s, opacity 0.3s;
}

#nav.scrolled .hamburger span {
  background: var(--text-body);
}

/* === Hero === */
#hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 0 2rem;
  background: url('../images/1.png') no-repeat center center;
  background-size: cover;
  color: #ffffff;
  overflow: hidden;
}

#hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(26,54,93,0.75) 0%, rgba(42,74,127,0.7) 50%, rgba(49,130,206,0.65) 100%);
  z-index: 0;
}

.hero-overlay {
  display: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
}

.hero-content h1 {
  color: #ffffff;
  font-size: 3.5rem;
  margin-bottom: 1.5rem;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

.hero-sub {
  font-size: 1.15rem;
  line-height: 1.8;
  margin-bottom: 2.5rem;
  opacity: 0.9;
  color: rgba(255, 255, 255, 0.9);
}

.hero-content .btn-lg {
  background: var(--accent);
  color: #ffffff;
  font-size: 1.15rem;
}

.hero-content .btn-lg:hover {
  background: #2f855a;
}

/* === Why China Cards === */
#why-china h2 {
  text-align: center;
  margin-bottom: 3rem;
}

.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.card {
  background: var(--bg-white);
  border-radius: var(--card-radius);
  padding: 2.5rem 2rem;
  box-shadow: var(--shadow);
  text-align: center;
  transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
}

.card-icon {
  margin-bottom: 1.5rem;
}

.card h3 {
  margin-bottom: 1rem;
  color: var(--primary);
}

.card p {
  font-size: 0.95rem;
  color: var(--text-body);
}

/* === Why Chongqing === */
#why-chongqing h2 {
  text-align: center;
  margin-bottom: 3rem;
}

.chongqing-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
}

.chongqing-text p {
  margin-bottom: 1.5rem;
}

.highlights {
  list-style: none;
  margin-bottom: 1.5rem;
}

.highlights li {
  padding: 0.75rem 0;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  font-size: 0.95rem;
}

.highlights li:last-child {
  border-bottom: none;
}

.source {
  font-size: 0.85rem;
  color: #718096;
  margin-bottom: 1.5rem;
}

.source a {
  color: var(--secondary);
  text-decoration: underline;
  text-underline-offset: 2px;
}

/* === Stat Boxes === */
.chongqing-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.stat-box {
  background: var(--primary);
  color: #ffffff;
  border-radius: var(--card-radius);
  padding: 2rem 1.5rem;
  text-align: center;
}

.stat-number {
  display: block;
  font-family: var(--font-heading);
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
}

.stat-label {
  font-size: 0.9rem;
  opacity: 0.8;
}

/* === Treatments === */
#treatments h2 {
  text-align: center;
  margin-bottom: 3rem;
}

.table-wrapper {
  overflow-x: auto;
  margin-bottom: 4rem;
}

.cost-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

.cost-table thead {
  background: var(--primary);
  color: #ffffff;
}

.cost-table th {
  padding: 1rem 1.5rem;
  text-align: left;
  font-weight: 600;
}

.cost-table td {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.cost-table tbody tr:hover {
  background: rgba(49, 130, 206, 0.04);
}

.cost-table td:last-child {
  color: var(--accent);
  font-weight: 700;
}

/* === Patient Stories === */
.stories h3 {
  text-align: center;
  margin-bottom: 2rem;
}

.story-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.story {
  background: var(--bg-white);
  border-left: 4px solid var(--secondary);
  border-radius: var(--card-radius);
  padding: 2rem;
  box-shadow: var(--shadow);
}

.story-name {
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 0.75rem;
  font-size: 1.05rem;
}

.story p:last-child {
  font-size: 0.95rem;
  color: var(--text-body);
}

/* === Process Steps === */
#process h2 {
  text-align: center;
  margin-bottom: 3rem;
}

.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
}

.step {
  text-align: center;
  position: relative;
}

.step-number {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  margin: 0 auto 1.5rem;
  background: var(--secondary);
  color: #ffffff;
  border-radius: 50%;
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
}

.step h3 {
  margin-bottom: 0.75rem;
  font-size: 1.2rem;
}

.step p {
  font-size: 0.95rem;
}

/* === Contact === */
#contact {
  text-align: center;
  background: var(--primary);
  color: #ffffff;
}

#contact h2 {
  color: #ffffff;
  margin-bottom: 1.5rem;
}

#contact p {
  font-size: 1.1rem;
  opacity: 0.9;
  margin-bottom: 2rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

#contact .btn-lg {
  background: var(--accent);
  color: #ffffff;
}

#contact .btn-lg:hover {
  background: #2f855a;
}

/* === Footer === */
footer {
  background: #0f2440;
  color: rgba(255, 255, 255, 0.6);
  padding: 2rem;
  text-align: center;
  font-size: 0.9rem;
}

/* === Scroll Fade Animations === */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

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

/* === Mobile Menu === */
@media (max-width: 767px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg-white);
    flex-direction: column;
    padding: 1.5rem 2rem;
    box-shadow: var(--shadow);
    gap: 1rem;
  }

  .nav-links.open {
    display: flex;
  }

  .hamburger {
    display: flex;
  }

  .hamburger.open span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }

  .hamburger.open span:nth-child(2) {
    opacity: 0;
  }

  .hamburger.open span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }

  .nav-cta {
    display: none;
  }
}

/* === Responsive: Tablet (768px - 1024px) === */
@media (max-width: 1024px) {
  h1 { font-size: 2.5rem; }
  h2 { font-size: 1.9rem; }

  .hero-content h1 { font-size: 2.5rem; }

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

  .chongqing-grid {
    grid-template-columns: 1fr;
  }

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

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

/* === Responsive: Mobile (<768px) === */
@media (max-width: 767px) {
  :root {
    --section-padding: 3rem 1rem;
  }

  h1 { font-size: 2rem; }
  h2 { font-size: 1.6rem; }
  h3 { font-size: 1.25rem; }

  .hero-content h1 { font-size: 2rem; }
  .hero-sub { font-size: 1rem; }

  .cards {
    grid-template-columns: 1fr;
  }

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

  .steps {
    grid-template-columns: 1fr;
  }

  .story-cards {
    grid-template-columns: 1fr;
  }

  .cost-table {
    font-size: 0.85rem;
  }

  .cost-table th,
  .cost-table td {
    padding: 0.75rem 0.75rem;
  }

  .stat-number {
    font-size: 2rem;
  }

  #nav {
    padding: 0.75rem 1rem;
  }

  .btn-lg {
    padding: 0.85rem 2rem;
    font-size: 1rem;
  }
}