:root {
  --primary-color: #064E3B; /* Very Dark Green (thay cho Navy Blue) */
  --secondary-color: #10B981; /* Bright Emerald Green */
  --accent-color: #059669; /* Emerald Green */
  --accent-hover: #047857; /* Darker Green */
  --bg-color: #F8FAFC; /* Off-White */
  --surface-color: #FFFFFF;
  --text-primary: #1E293B;
  --text-secondary: #475569;
  --text-light: #F8FAFC;
  
  /* Cải thiện chiều sâu (Shadows) */
  --shadow-sm: 0 2px 4px rgba(0,0,0,0.02);
  --shadow-md: 0 10px 20px rgba(0,0,0,0.04);
  --shadow-lg: 0 20px 40px rgba(0,0,0,0.08);
  --shadow-xl: 0 30px 60px rgba(6, 78, 59, 0.12); /* Shadow mang sắc tố xanh rêu */
  --shadow-glow: 0 12px 30px -5px rgba(16, 185, 129, 0.4);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Inter', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  font-family: 'Outfit', sans-serif;
  color: var(--primary-color);
  line-height: 1.2;
}

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

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Buttons có chiều sâu hơn */
.btn {
  display: inline-block;
  padding: 16px 32px;
  border-radius: 12px;
  font-weight: 600;
  font-family: 'Outfit', sans-serif;
  text-align: center;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  border: none;
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: linear-gradient(135deg, var(--secondary-color) 0%, var(--accent-color) 100%);
  color: #fff;
  box-shadow: var(--shadow-glow);
  border: 1px solid rgba(255,255,255,0.2);
}

.btn-primary::after {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: all 0.5s ease;
}

.btn-primary:hover::after {
  left: 100%;
}

.btn-primary:hover {
  background: linear-gradient(135deg, var(--accent-color) 0%, var(--accent-hover) 100%);
  transform: translateY(-4px);
  box-shadow: 0 20px 35px -5px rgba(16, 185, 129, 0.5);
}

.btn-secondary {
  background-color: transparent;
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
}

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

/* Glassmorphism utility */
.glass {
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

/* Navigation */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  padding: 16px 0;
  transition: all 0.3s ease;
}

header.scrolled {
  background-color: var(--surface-color);
  box-shadow: var(--shadow-md);
}

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

.logo {
  font-family: 'Outfit', sans-serif;
  font-size: 26px;
  font-weight: 800;
  color: var(--primary-color);
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo-icon {
  color: var(--secondary-color);
}

/* Hero Section có chiều sâu */
.hero {
  padding: 180px 0 120px;
  background: radial-gradient(circle at 100% 0%, rgba(16, 185, 129, 0.08) 0%, rgba(248, 250, 252, 1) 50%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 50%;
  background: linear-gradient(to top, #FFFFFF, transparent);
  pointer-events: none;
}

.hero-content {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 60px;
  align-items: center;
  position: relative;
  z-index: 2;
}

.hero-text h1 {
  font-size: 56px;
  margin-bottom: 24px;
  letter-spacing: -1px;
}

.hero-text p {
  font-size: 20px;
  color: var(--text-secondary);
  margin-bottom: 40px;
  line-height: 1.7;
}

.hero-badges {
  display: flex;
  gap: 24px;
  margin-top: 40px;
  font-size: 15px;
  color: var(--text-secondary);
  font-weight: 500;
}

.hero-badges span {
  display: flex;
  align-items: center;
  gap: 8px;
  background: #fff;
  padding: 10px 16px;
  border-radius: 20px;
  box-shadow: var(--shadow-sm);
  border: 1px solid rgba(0,0,0,0.02);
}

.hero-badges span i {
  color: var(--secondary-color);
}

.hero-image {
  position: relative;
}

.hero-image::after {
  content: '';
  position: absolute;
  inset: -20px;
  background: linear-gradient(135deg, var(--secondary-color) 0%, transparent 50%);
  border-radius: 30px;
  z-index: -1;
  opacity: 0.15;
  filter: blur(20px);
}

.hero-image img {
  width: 100%;
  border-radius: 24px;
  box-shadow: var(--shadow-xl);
  border: 1px solid rgba(255,255,255,0.6);
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-15px); }
  100% { transform: translateY(0px); }
}

/* Social Proof */
.social-proof {
  padding: 60px 0;
  background-color: var(--surface-color);
  text-align: center;
  border-bottom: 1px solid rgba(0,0,0,0.03);
}

.social-proof p {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 30px;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  font-weight: 600;
}

.logos {
  display: flex;
  justify-content: center;
  gap: 60px;
  flex-wrap: wrap;
  opacity: 0.5;
}

.logos h2 {
  font-size: 24px;
  color: var(--text-secondary);
  filter: grayscale(100%);
  transition: all 0.3s ease;
}

.logos h2:hover {
  filter: grayscale(0%);
  color: var(--primary-color);
  opacity: 1;
  transform: scale(1.05);
}

/* Section Shared */
.section {
  padding: 120px 0;
}

.section-header {
  text-align: center;
  max-width: 800px;
  margin: 0 auto 80px;
}

.section-header h2 {
  font-size: 42px;
  margin-bottom: 20px;
  letter-spacing: -0.5px;
}

.section-header p {
  color: var(--text-secondary);
  font-size: 18px;
  line-height: 1.8;
}

/* Agitation (Pain points) - Tăng chiều sâu */
.agitation-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
}

.pain-card {
  background-color: var(--surface-color);
  padding: 50px 40px;
  border-radius: 20px;
  box-shadow: var(--shadow-md);
  text-align: center;
  border: 1px solid rgba(0,0,0,0.04);
  transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  position: relative;
  overflow: hidden;
}

.pain-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: var(--primary-color);
  opacity: 0;
  transition: opacity 0.3s;
}

.pain-card:hover {
  transform: translateY(-15px);
  box-shadow: var(--shadow-xl);
}

.pain-card:hover::before {
  opacity: 1;
}

.pain-icon {
  width: 80px;
  height: 80px;
  margin: 0 auto 24px;
  background: var(--bg-color);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 32px;
  color: var(--primary-color);
  box-shadow: inset 0 2px 4px rgba(0,0,0,0.05);
}

.pain-card h3 {
  font-size: 22px;
  margin-bottom: 16px;
}

.pain-card p {
  color: var(--text-secondary);
  font-size: 16px;
  line-height: 1.6;
}

/* Solution / Benefits */
.benefits {
  background-color: var(--primary-color);
  color: var(--text-light);
  position: relative;
  overflow: hidden;
}

.benefits::before {
  content: '';
  position: absolute;
  top: -200px;
  right: -200px;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(16, 185, 129, 0.15) 0%, transparent 70%);
  border-radius: 50%;
}

.benefits .section-header h2,
.benefits .section-header p {
  color: var(--text-light);
}

.benefits-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 50px;
  position: relative;
  z-index: 2;
}

.benefit-item {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  background: rgba(255,255,255,0.03);
  padding: 30px;
  border-radius: 20px;
  border: 1px solid rgba(255,255,255,0.05);
  transition: background 0.3s ease;
}

.benefit-item:hover {
  background: rgba(255,255,255,0.08);
}

.benefit-icon {
  background: linear-gradient(135deg, var(--secondary-color) 0%, var(--accent-color) 100%);
  color: #fff;
  width: 64px;
  height: 64px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  flex-shrink: 0;
  box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

.benefit-content h3 {
  color: var(--text-light);
  font-size: 22px;
  margin-bottom: 12px;
}

.benefit-content p {
  color: rgba(255,255,255,0.7);
  font-size: 16px;
  line-height: 1.7;
}

/* Curriculum Accordion */
.accordion {
  max-width: 800px;
  margin: 0 auto;
}

.accordion-item {
  background-color: var(--surface-color);
  border-radius: 16px;
  margin-bottom: 20px;
  box-shadow: var(--shadow-sm);
  border: 1px solid rgba(0,0,0,0.05);
  overflow: hidden;
  transition: box-shadow 0.3s ease;
}

.accordion-item:hover {
  box-shadow: var(--shadow-md);
}

.accordion-header {
  padding: 24px 30px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  font-family: 'Outfit', sans-serif;
  font-weight: 600;
  font-size: 20px;
  color: var(--primary-color);
}

.accordion-icon {
  transition: transform 0.4s ease;
  color: var(--secondary-color);
  background: rgba(16, 185, 129, 0.1);
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
}

.accordion-item.active .accordion-icon {
  transform: rotate(180deg);
  background: var(--secondary-color);
  color: #fff;
}

.accordion-body {
  padding: 0 30px;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.4s ease;
  color: var(--text-secondary);
}

.accordion-item.active .accordion-body {
  padding: 0 30px 24px;
  max-height: 500px;
}

.accordion-body ul {
  list-style: none;
  padding-left: 0;
}

.accordion-body ul li {
  margin-bottom: 12px;
  position: relative;
  padding-left: 28px;
  font-size: 16px;
}

.accordion-body ul li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--secondary-color);
  font-weight: bold;
}

/* Instructor */
.instructor {
  background-color: var(--surface-color);
}

.instructor-content {
  display: flex;
  align-items: center;
  gap: 80px;
  max-width: 1000px;
  margin: 0 auto;
}

.instructor-image {
  flex-shrink: 0;
  width: 380px;
  height: 380px;
  border-radius: 24px;
  overflow: hidden;
  box-shadow: var(--shadow-xl);
  position: relative;
}

.instructor-image::before {
  content: '';
  position: absolute;
  inset: 0;
  border: 2px solid rgba(255,255,255,0.5);
  border-radius: 24px;
  z-index: 2;
  pointer-events: none;
}

.instructor-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.instructor-image:hover img {
  transform: scale(1.05);
}

.instructor-info h3 {
  font-size: 36px;
  margin-bottom: 10px;
}

.instructor-title {
  display: inline-block;
  color: var(--secondary-color);
  background: rgba(16, 185, 129, 0.1);
  padding: 6px 16px;
  border-radius: 20px;
  font-weight: 600;
  margin-bottom: 24px;
  font-size: 14px;
  letter-spacing: 0.5px;
}

.instructor-info p {
  color: var(--text-secondary);
  margin-bottom: 30px;
  font-size: 17px;
  line-height: 1.8;
}

.instructor-stats {
  display: flex;
  gap: 40px;
}

.stat {
  text-align: left;
}

.stat-num {
  font-size: 32px;
  font-weight: 800;
  color: var(--primary-color);
  font-family: 'Outfit', sans-serif;
  margin-bottom: 4px;
}

.stat-text {
  font-size: 14px;
  color: var(--text-secondary);
  font-weight: 500;
}

/* Pricing - Tăng độ nổi bật */
.pricing {
  background: linear-gradient(135deg, #F1F5F9 0%, #E2E8F0 100%);
}

.pricing-card {
  background-color: var(--surface-color);
  max-width: 550px;
  margin: 0 auto;
  border-radius: 30px;
  padding: 60px 50px;
  box-shadow: var(--shadow-xl);
  position: relative;
  border: 4px solid var(--secondary-color);
}

.popular-badge {
  position: absolute;
  top: -20px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, var(--secondary-color) 0%, var(--accent-color) 100%);
  color: #fff;
  padding: 10px 24px;
  border-radius: 30px;
  font-size: 15px;
  font-weight: 700;
  font-family: 'Outfit', sans-serif;
  box-shadow: var(--shadow-glow);
  white-space: nowrap;
}

.price-header {
  text-align: center;
  margin-bottom: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid #E2E8F0;
}

.price-header h3 {
  font-size: 28px;
  margin-bottom: 16px;
}

.original-price {
  text-decoration: line-through;
  color: #94A3B8;
  font-size: 20px;
  font-weight: 500;
}

.current-price {
  font-size: 56px;
  font-family: 'Outfit', sans-serif;
  color: var(--primary-color);
  font-weight: 800;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  gap: 8px;
  line-height: 1;
  margin-top: 10px;
}

.current-price span {
  font-size: 24px;
  color: var(--text-secondary);
  font-weight: 600;
  margin-top: 8px;
}

.price-features ul {
  list-style: none;
  margin-bottom: 40px;
}

.price-features li {
  margin-bottom: 20px;
  display: flex;
  align-items: flex-start;
  gap: 16px;
  color: var(--text-primary);
  font-size: 17px;
}

.price-features li i {
  color: var(--secondary-color);
  font-size: 20px;
  margin-top: 2px;
}

.guarantee {
  text-align: center;
  margin-top: 24px;
  font-size: 14px;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  background: rgba(16, 185, 129, 0.05);
  padding: 12px;
  border-radius: 8px;
}

/* Footer */
footer {
  background-color: var(--primary-color);
  color: rgba(255,255,255,0.7);
  padding: 80px 0 40px;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 60px;
  padding-bottom: 60px;
  border-bottom: 1px solid rgba(255,255,255,0.1);
}

.footer-logo {
  font-family: 'Outfit', sans-serif;
  font-size: 28px;
  font-weight: 800;
  color: #fff;
  display: flex;
  align-items: center;
  gap: 10px;
}

.footer-links {
  display: flex;
  gap: 40px;
}

.footer-links a {
  font-weight: 500;
  transition: color 0.3s ease;
}

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

.copyright {
  text-align: center;
  font-size: 15px;
}

/* Responsive */
@media (max-width: 992px) {
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  .hero-badges {
    justify-content: center;
  }
  
  .agitation-grid, .benefits-grid {
    grid-template-columns: 1fr 1fr;
  }
  
  .instructor-content {
    flex-direction: column;
    text-align: center;
  }
  
  .instructor-stats {
    justify-content: center;
  }
}

@media (max-width: 768px) {
  .hero-text h1 {
    font-size: 42px;
  }
  
  .agitation-grid, .benefits-grid {
    grid-template-columns: 1fr;
  }
  
  .footer-content {
    flex-direction: column;
    gap: 30px;
  }
}