:root {
  --sd-bg: #F0F4F8;          /* Màu nền cơ bản, hơi xám dịu */
  --sd-surface: rgba(255, 255, 255, 0.85); /* Trắng trong suốt (Glass) */
  --sd-surface-solid: #FFFFFF;
  --sd-text: #1A202C;        /* Chữ tối đậm */
  --sd-text-light: #4A5568;
  
  --sd-blue-soft: #EBF8FF;
  --sd-blue-medium: #63B3ED;
  --sd-blue: #2B6CB0;        /* Xanh y tế đậm, tin cậy */
  --sd-blue-dark: #2C5282;
  
  --sd-orange-warm: #DD6B20; /* Cam ấm */
  --sd-orange-light: #FBD38D;
  --sd-orange-bg: #FFFAF0;
  
  --sd-border: rgba(226, 232, 240, 0.6);
  --sd-border-radius: 16px;
  
  --font-family: "Inter", "Segoe UI", "Roboto", "Helvetica Neue", sans-serif;
  
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -1px rgba(0,0,0,0.03);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.05), 0 4px 6px -2px rgba(0,0,0,0.025);
  --shadow-hover: 0 20px 25px -5px rgba(0,0,0,0.08), 0 10px 10px -5px rgba(0,0,0,0.04);
}

body {
  margin: 0;
  font-family: var(--font-family);
  background-color: var(--sd-bg);
  background-image: 
    radial-gradient(circle at 15% 0%, #EBF8FF 0%, transparent 40%),
    radial-gradient(circle at 85% 10%, #FFFAF0 0%, transparent 40%);
  background-attachment: fixed;
  color: var(--sd-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* Base typography */
h1, h2, h3, h4 {
  color: var(--sd-text);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2.5rem, 5vw, 4rem); margin-bottom: 1.25rem; }
h2 { font-size: clamp(2rem, 4vw, 2.5rem); margin-bottom: 1rem; }
h3 { font-size: 1.25rem; margin-bottom: 0.75rem; }
p { margin-top: 0; margin-bottom: 1.25rem; }

a {
  color: var(--sd-blue);
  text-decoration: none;
  transition: color 0.2s;
}
a:hover { color: var(--sd-blue-dark); text-decoration: underline; }

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* Utilities */
.eyebrow {
  display: inline-block;
  font-size: 0.875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--sd-blue);
  background: var(--sd-blue-soft);
  padding: 0.35rem 1rem;
  border-radius: 9999px;
  margin-bottom: 1.5rem;
}

.text-gradient {
  background: linear-gradient(135deg, var(--sd-blue-dark), var(--sd-blue));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Header & Nav */
.site-header {
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--sd-border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  transition: background 0.3s ease;
}
.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.brand {
  font-size: 1.5rem;
  font-weight: 900;
  color: var(--sd-blue-dark);
  letter-spacing: -0.03em;
}
.brand span {
  color: var(--sd-orange-warm);
}
.brand:hover { text-decoration: none; opacity: 0.9; }

.nav-list {
  display: flex;
  list-style: none;
  gap: 2rem;
  margin: 0;
  padding: 0;
}
.nav-list a {
  color: var(--sd-text-light);
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.2s ease;
  padding: 0.5rem 0;
  position: relative;
}
.nav-list a:after {
  content: '';
  position: absolute;
  width: 0;
  height: 2px;
  bottom: 0;
  left: 0;
  background-color: var(--sd-blue);
  transition: width 0.2s ease;
}
.nav-list a:hover, .nav-list a[aria-current="page"] {
  color: var(--sd-blue-dark);
  text-decoration: none;
}
.nav-list a:hover:after, .nav-list a[aria-current="page"]:after {
  width: 100%;
}

/* Buttons */
.button-row { display: flex; gap: 1rem; flex-wrap: wrap; }
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.875rem 1.75rem;
  border-radius: 99px;
  font-weight: 600;
  font-size: 1rem;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
}
.button-primary {
  background: linear-gradient(135deg, var(--sd-blue), var(--sd-blue-dark));
  color: white !important;
  border: none;
}
.button-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 15px rgba(43, 108, 176, 0.3);
  text-decoration: none;
}
.button-secondary {
  background-color: var(--sd-surface-solid);
  color: var(--sd-text) !important;
  border: 1px solid var(--sd-border);
}
.button-secondary:hover {
  background-color: var(--sd-blue-soft);
  color: var(--sd-blue-dark) !important;
  border-color: var(--sd-blue-medium);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  text-decoration: none;
}

/* Hero Section */
.hero {
  padding: 6rem 0 4rem;
  position: relative;
}
.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 4rem;
  align-items: center;
}
.hero-lead {
  font-size: 1.25rem;
  color: var(--sd-text-light);
  margin-bottom: 2.5rem;
  max-width: 90%;
}

/* Hero Visual & Glassmorphism */
.hero-visual {
  position: relative;
}
.tracking-card {
  background: var(--sd-surface);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(255, 255, 255, 0.5);
  border-radius: var(--sd-border-radius);
  padding: 2.5rem;
  box-shadow: var(--shadow-lg);
  position: relative;
  z-index: 2;
  overflow: hidden;
}
/* Abstract decoration behind card */
.hero-visual::before {
  content: '';
  position: absolute;
  top: -20px;
  right: -20px;
  width: 150px;
  height: 150px;
  background: var(--sd-orange-light);
  border-radius: 50%;
  filter: blur(40px);
  opacity: 0.6;
  z-index: 1;
}
.hero-visual::after {
  content: '';
  position: absolute;
  bottom: -30px;
  left: -20px;
  width: 200px;
  height: 200px;
  background: var(--sd-blue-medium);
  border-radius: 50%;
  filter: blur(50px);
  opacity: 0.4;
  z-index: 1;
}

.tracking-card h3 {
  font-size: 1.125rem;
  color: var(--sd-text-light);
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.tracking-card h3::before {
  content: '';
  display: inline-block;
  width: 12px;
  height: 12px;
  background: var(--sd-blue);
  border-radius: 50%;
  box-shadow: 0 0 0 4px var(--sd-blue-soft);
}

/* SVG Chart Animation */
.chart-line {
  stroke-dasharray: 1000;
  stroke-dashoffset: 1000;
  animation: drawLine 2s cubic-bezier(0.4, 0, 0.2, 1) forwards;
  animation-delay: 0.5s;
}
.chart-point {
  opacity: 0;
  transform: scale(0);
  transform-origin: center;
  animation: popIn 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
}
.chart-point:nth-child(1) { animation-delay: 1.2s; }
.chart-point:nth-child(2) { animation-delay: 1.6s; }
.chart-point:nth-child(3) { animation-delay: 2.0s; }

@keyframes drawLine {
  to { stroke-dashoffset: 0; }
}
@keyframes popIn {
  to { opacity: 1; transform: scale(1); }
}

/* Warnings */
.warning-panel {
  background: var(--sd-orange-bg);
  border: 1px solid var(--sd-orange-light);
  border-left: 5px solid var(--sd-orange-warm);
  border-radius: 12px;
  padding: 1.5rem 2rem;
  margin-top: 2rem;
  position: relative;
  z-index: 3;
  box-shadow: var(--shadow-md);
  display: flex;
  gap: 1rem;
  align-items: flex-start;
}
.warning-icon {
  background: var(--sd-orange-warm);
  color: white;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  flex-shrink: 0;
  margin-top: 0.25rem;
}
.warning-content h3 {
  color: var(--sd-orange-warm);
  margin-top: 0;
  margin-bottom: 0.5rem;
  font-size: 1.125rem;
}
.warning-content p {
  margin: 0;
  font-size: 0.95rem;
  color: #7B341E;
}

/* Detail Section */
.detail-section {
  padding: 6rem 0;
}
.feature-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
  margin-top: 4rem;
}
.feature-grid:nth-child(even) {
  direction: rtl;
}
.feature-grid:nth-child(even) > * {
  direction: ltr;
}
.feature-text h3 {
  font-size: 2rem;
  color: var(--sd-blue-dark);
}
.feature-text p {
  color: var(--sd-text-light);
  font-size: 1.125rem;
}
.feature-image {
  background: var(--sd-surface-solid);
  border-radius: var(--sd-border-radius);
  padding: 2rem;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--sd-border);
}

/* Cards (Path Grid) */
.path-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  margin-top: 4rem;
}
.path-card {
  background: var(--sd-surface-solid);
  border: 1px solid var(--sd-border);
  border-radius: var(--sd-border-radius);
  padding: 2.5rem 2rem;
  display: flex;
  flex-direction: column;
  color: var(--sd-text);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}
.path-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; width: 100%; height: 4px;
  background: linear-gradient(90deg, var(--sd-blue), var(--sd-blue-medium));
  opacity: 0;
  transition: opacity 0.3s;
}
.path-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-hover);
  text-decoration: none;
  border-color: transparent;
}
.path-card:hover::before {
  opacity: 1;
}

.path-icon {
  width: 48px;
  height: 48px;
  background: var(--sd-blue-soft);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.5rem;
  color: var(--sd-blue);
  transition: transform 0.3s;
}
.path-card:hover .path-icon {
  transform: scale(1.1);
  background: var(--sd-blue);
  color: white;
}
.path-icon svg {
  width: 24px;
  height: 24px;
}

.path-card h3 {
  margin-top: 0;
  color: var(--sd-blue-dark);
  font-size: 1.25rem;
}
.path-card p {
  color: var(--sd-text-light);
  margin-bottom: 0;
  font-size: 1rem;
  line-height: 1.6;
}
.arrow-icon {
  margin-top: auto;
  padding-top: 1.5rem;
  color: var(--sd-blue);
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: gap 0.2s;
}
.path-card:hover .arrow-icon {
  gap: 0.75rem;
}

/* Footer & Coop */
.cooperation-panel {
  background: var(--sd-surface-solid);
  border: 1px dashed var(--sd-blue-medium);
  border-radius: var(--sd-border-radius);
  padding: 4rem;
  margin: 6rem auto 2rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.cooperation-panel::after {
  content: '';
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0;
  background: linear-gradient(135deg, rgba(235, 248, 255, 0.5), transparent);
  pointer-events: none;
}
.cooperation-panel h2 {
  margin-top: 0;
  font-size: 2rem;
  color: var(--sd-blue-dark);
}

.site-footer {
  background: var(--sd-surface-solid);
  border-top: 1px solid var(--sd-border);
  padding: 4rem 0 2rem;
}
.footer-main {
  display: grid;
  grid-template-columns: 1.5fr 2fr;
  gap: 4rem;
  margin-bottom: 3rem;
}
.footer-links {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem 2rem;
  align-content: start;
}
.footer-links a {
  color: var(--sd-text-light);
  font-weight: 500;
}
.footer-links a:hover {
  color: var(--sd-blue);
}
.footer-bottom {
  border-top: 1px solid var(--sd-border);
  padding-top: 2rem;
  display: flex;
  justify-content: space-between;
  color: var(--sd-text-light);
  font-size: 0.875rem;
}

/* Content Pages */
.page-header {
  background: var(--sd-surface-solid);
  padding: 4rem 0;
  border-bottom: 1px solid var(--sd-border);
  margin-bottom: 4rem;
}
.page-content {
  margin-bottom: 6rem;
}
.under-construction {
  background: var(--sd-surface-solid);
  border-radius: var(--sd-border-radius);
  padding: 4rem;
  text-align: center;
  border: 1px dashed var(--sd-blue-medium);
  box-shadow: var(--shadow-sm);
  position: relative;
  overflow: hidden;
}
.under-construction::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; height: 4px;
  background: repeating-linear-gradient(45deg, var(--sd-blue-medium), var(--sd-blue-medium) 10px, transparent 10px, transparent 20px);
}
.under-construction h2 {
  color: var(--sd-blue-dark);
}
.under-construction p {
  color: var(--sd-text-light);
  max-width: 600px;
  margin: 1rem auto 2rem;
  font-size: 1.125rem;
}

@media (max-width: 768px) {
  .hero-grid { grid-template-columns: 1fr; gap: 3rem; text-align: center; }
  .hero-lead { margin-left: auto; margin-right: auto; }
  .button-row { justify-content: center; }
  .path-grid { grid-template-columns: 1fr; }
  .footer-main { grid-template-columns: 1fr; gap: 2rem; }
  .feature-grid { grid-template-columns: 1fr; gap: 2rem; text-align: center; }
  .feature-grid:nth-child(even) { direction: ltr; }
}