/* ===============================================
   VietD - Vietnam Entrepreneur Training Institute
   Design System: Navy + Gold Premium
   =============================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=Lato:wght@300;400;700;900&family=JetBrains+Mono:wght@400&display=swap');

:root {
  --navy: #092051;
  --navy-light: #122a5d;
  --navy-mid: #1e376d;
  --gold: #B8860B;
  --gold-light: #D4A843;
  --gold-pale: #F3E5AB;
  --blue: #0369A1;
  --blue-light: #1e376d;
  --white: #FFFFFF;
  --light: #F8FAFC;
  --gray-50: #F9FAFB;
  --gray-100: #dee2ea;
  --gray-200: #dee2ea;
  --gray-300: #D1D5DB;
  --gray-500: #798296;
  --gray-600: #4B5563;
  --gray-700: #374151;
  --gray-800: #1F2937;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.12);
  --shadow-xl: 0 20px 50px rgba(0, 0, 0, 0.15);
  --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
  font-family: 'Lato', 'Inter', system-ui, sans-serif;
  color: var(--gray-700);
  background: var(--light);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: 'Inter', sans-serif;
  line-height: 1.3;
  color: var(--navy);
}

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

img {
  max-width: 100%;
  height: auto;
}

ul {
  list-style: none;
}

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

.section-padding {
  padding: 100px 0;
}

/* ============ NAVBAR ============ */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  transition: var(--transition);
}

.navbar.scrolled {
  box-shadow: var(--shadow-md);
}

.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.nav-logo img {
  height: 50px;
  width: auto;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 36px;
}

.nav-links a {
  font-family: 'Inter', sans-serif;
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--gray-600);
  position: relative;
  padding: 4px 0;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gold);
  transition: width 0.3s ease;
}

.nav-links a:hover {
  color: var(--navy);
}

.nav-links a:hover::after {
  width: 100%;
}

.nav-cta {
  background: var(--navy);
  color: var(--white) !important;
  padding: 10px 28px !important;
  border-radius: 6px;
  font-size: 0.78rem !important;
  letter-spacing: 1px;
  border: 2px solid var(--navy);
}

.nav-cta::after {
  display: none !important;
}

.nav-cta:hover {
  background: var(--gold) !important;
  border-color: var(--gold);
}

/* Mobile menu */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
}

.hamburger span {
  width: 24px;
  height: 2px;
  background: var(--navy);
  transition: var(--transition);
}

/* ============ HERO SLIDER ============ */
.hero {
  position: relative;
  height: 100vh;
  min-height: 600px;
  overflow: hidden;
  margin-top: 80px;
}

.hero-slide {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 1.2s ease-in-out;
}

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

.hero-slide-bg {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
}

.hero-slide-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(15, 23, 42, 0.85) 0%, rgba(15, 23, 42, 0.6) 50%, rgba(3, 105, 161, 0.4) 100%);
}

.hero-content {
  position: relative;
  z-index: 10;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 0 60px;
  max-width: 800px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(184, 134, 11, 0.2);
  border: 1px solid rgba(184, 134, 11, 0.4);
  color: var(--gold-light);
  padding: 8px 20px;
  border-radius: 50px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 24px;
  width: fit-content;
  animation: fadeInUp 0.8s ease forwards;
}

.hero h1 {
  font-size: 3.2rem;
  font-weight: 800;
  color: var(--white);
  margin-bottom: 20px;
  line-height: 1.15;
  animation: fadeInUp 0.8s 0.2s ease both;
}

.hero h1 .gold {
  color: var(--gold-light);
}

.hero p {
  font-size: 1.15rem;
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: 36px;
  max-width: 600px;
  line-height: 1.8;
  animation: fadeInUp 0.8s 0.4s ease both;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  animation: fadeInUp 0.8s 0.6s ease both;
}

.btn-primary {
  background: var(--gold);
  color: var(--white);
  padding: 14px 36px;
  border-radius: 6px;
  font-family: 'Inter', sans-serif;
  font-weight: 700;
  font-size: 0.85rem;
  letter-spacing: 1px;
  text-transform: uppercase;
  border: 2px solid var(--gold);
  cursor: pointer;
  transition: var(--transition);
}

.btn-primary:hover {
  background: transparent;
  color: var(--gold);
}

.btn-outline {
  background: transparent;
  color: var(--white);
  padding: 14px 36px;
  border-radius: 6px;
  font-family: 'Inter', sans-serif;
  font-weight: 700;
  font-size: 0.85rem;
  letter-spacing: 1px;
  text-transform: uppercase;
  border: 2px solid rgba(255, 255, 255, 0.4);
  cursor: pointer;
  transition: var(--transition);
}

.btn-outline:hover {
  border-color: var(--white);
  background: rgba(255, 255, 255, 0.1);
}

/* Slider dots */
.slider-dots {
  position: absolute;
  bottom: 40px;
  left: 60px;
  z-index: 20;
  display: flex;
  gap: 12px;
}

.slider-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.3);
  cursor: pointer;
  transition: var(--transition);
  border: none;
}

.slider-dot.active {
  background: var(--gold);
  width: 36px;
  border-radius: 6px;
}

/* ============ STATS BAR ============ */
.stats-bar {
  background: var(--navy);
  padding: 0;
  position: relative;
  z-index: 5;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}

.stat-item {
  padding: 40px 30px;
  text-align: center;
  border-right: 1px solid rgba(255, 255, 255, 0.08);
  transition: var(--transition);
}

.stat-item:last-child {
  border-right: none;
}

.stat-item:hover {
  background: rgba(184, 134, 11, 0.1);
}

.stat-number {
  font-family: 'Inter', sans-serif;
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--gold-light);
  margin-bottom: 4px;
}

.stat-label {
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.85rem;
  letter-spacing: 1px;
  text-transform: uppercase;
}

/* ============ ABOUT / GIỚI THIỆU ============ */
.about {
  background: var(--white);
}

.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: center;
}

.about-image {
  position: relative;
}

.about-image img {
  border-radius: 12px;
  box-shadow: var(--shadow-xl);
}

.about-image .accent-box {
  position: absolute;
  bottom: -20px;
  right: -20px;
  width: 200px;
  padding: 24px;
  background: var(--gold);
  border-radius: 12px;
  color: var(--white);
  text-align: center;
  box-shadow: var(--shadow-lg);
}

.about-image .accent-box .number {
  font-family: 'Inter';
  font-size: 2rem;
  font-weight: 800;
}

.about-image .accent-box .label {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.section-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  color: var(--blue);
  letter-spacing: 3px;
  text-transform: uppercase;
  margin-bottom: 12px;
  display: block;
}

.section-title {
  font-size: 2.4rem;
  font-weight: 800;
  margin-bottom: 20px;
}

.section-title .gold {
  color: var(--gold);
}

.gold-bar {
  width: 60px;
  height: 4px;
  background: var(--gold);
  border-radius: 2px;
  margin-bottom: 24px;
}

.about-text p {
  margin-bottom: 16px;
  color: var(--gray-600);
  text-align: justify;
}

.about-values {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 32px;
}

.about-value {
  padding: 20px;
  background: var(--gray-50);
  border-radius: 10px;
  text-align: center;
  border: 1px solid var(--gray-200);
  transition: var(--transition);
}

.about-value:hover {
  border-color: var(--gold);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.about-value i {
  font-size: 1.8rem;
  color: var(--gold);
  margin-bottom: 10px;
}

.about-value h4 {
  font-size: 0.9rem;
  margin-bottom: 4px;
}

.about-value p {
  font-size: 0.78rem;
  color: var(--gray-500);
  margin: 0;
}

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

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

.section-header .gold-bar {
  margin: 0 auto 24px;
}

.section-desc {
  max-width: 600px;
  margin: 0 auto;
  color: var(--gray-500);
}

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

.service-card {
  background: var(--white);
  border-radius: 16px;
  padding: 40px 32px;
  text-align: center;
  border: 1px solid var(--gray-200);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--gold), var(--blue));
  transform: scaleX(0);
  transition: transform 0.4s ease;
  transform-origin: left;
}

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

.service-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-xl);
  border-color: transparent;
}

.service-icon {
  width: 72px;
  height: 72px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  font-size: 1.8rem;
  background: linear-gradient(135deg, var(--navy), var(--navy-light));
  color: var(--gold-light);
}

.service-card h3 {
  font-size: 1.15rem;
  margin-bottom: 12px;
}

.service-card p {
  font-size: 0.9rem;
  color: var(--gray-500);
  line-height: 1.7;
}

/* ============ COURSES / KHÓA HỌC ============ */
.courses {
  background: var(--white);
}

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

.course-card {
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--gray-200);
  transition: var(--transition);
  background: var(--white);
}

.course-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-xl);
}

.course-img {
  height: 200px;
  background-size: cover;
  background-position: center;
  position: relative;
}

.course-badge {
  position: absolute;
  top: 16px;
  left: 16px;
  background: var(--gold);
  color: var(--white);
  padding: 4px 14px;
  border-radius: 50px;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.course-body {
  padding: 28px;
}

.course-body h3 {
  font-size: 1.1rem;
  margin-bottom: 10px;
  line-height: 1.4;
}

.course-body p {
  font-size: 0.85rem;
  color: var(--gray-500);
  margin-bottom: 20px;
}

.course-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 16px;
  border-top: 1px solid var(--gray-100);
}

.course-meta span {
  font-size: 0.8rem;
  color: var(--gray-500);
  display: flex;
  align-items: center;
  gap: 6px;
}

.course-meta .price {
  color: var(--gold);
  font-weight: 700;
  font-size: 0.95rem;
}

/* ============ TEAM / ĐỘI NGŨ ============ */
.team {
  background: var(--navy);
  color: var(--white);
}

.team .section-label {
  color: var(--gold-light);
}

.team .section-title {
  color: var(--white);
}

.team .section-desc {
  color: rgba(255, 255, 255, 0.5);
}

.team .gold-bar {
  background: var(--gold-light);
}

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

.team-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 16px;
  padding: 40px 28px;
  text-align: center;
  transition: var(--transition);
  backdrop-filter: blur(10px);
}

.team-card:hover {
  background: rgba(255, 255, 255, 0.1);
  transform: translateY(-6px);
  border-color: var(--gold);
}

.team-avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  margin: 0 auto 20px;
  overflow: hidden;
  border: 3px solid var(--gold);
  box-shadow: 0 0 30px rgba(184, 134, 11, 0.3);
}

.team-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.team-card h3 {
  color: var(--white);
  font-size: 1.15rem;
  margin-bottom: 4px;
}

.team-card .role {
  color: var(--gold-light);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 16px;
}

.team-card p {
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.85rem;
}

.team-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
  margin-top: 16px;
}

.team-tag {
  background: rgba(184, 134, 11, 0.15);
  border: 1px solid rgba(184, 134, 11, 0.3);
  color: var(--gold-light);
  padding: 4px 12px;
  border-radius: 50px;
  font-size: 0.7rem;
  font-family: 'JetBrains Mono', monospace;
}

/* ============ EXPERTS / CHUYÊN GIA ============ */
.experts {
  background: var(--gray-50);
}

.experts-slider {
  position: relative;
  overflow: hidden;
}

.experts-track {
  display: flex;
  transition: transform 0.6s ease;
}

.expert-slide {
  min-width: 100%;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  padding: 0 4px;
}

.expert-card {
  background: var(--white);
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--gray-200);
  transition: var(--transition);
  text-align: center;
}

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

.expert-photo {
  height: 220px;
  background-size: cover;
  background-position: center top;
  position: relative;
}

.expert-photo::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 60px;
  background: linear-gradient(transparent, var(--white));
}

.expert-info {
  padding: 16px 20px 24px;
}

.expert-info h4 {
  font-size: 0.95rem;
  margin-bottom: 4px;
}

.expert-info .specialty {
  font-size: 0.78rem;
  color: var(--gold);
  font-weight: 600;
  margin-bottom: 8px;
}

.expert-info p {
  font-size: 0.78rem;
  color: var(--gray-500);
}

.experts-nav {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 36px;
}

.experts-nav button {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 2px solid var(--navy);
  background: transparent;
  color: var(--navy);
  cursor: pointer;
  font-size: 1rem;
  transition: var(--transition);
}

.experts-nav button:hover {
  background: var(--navy);
  color: var(--white);
}

/* ============ PARTNERS ============ */
.partners {
  background: var(--white);
}

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

.partners-logos img {
  height: 50px;
  filter: grayscale(1);
  transition: var(--transition);
}

.partners-logos img:hover {
  filter: grayscale(0);
  opacity: 1;
}

/* ============ CTA ============ */
.cta {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-light) 50%, var(--blue) 100%);
  padding: 100px 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.cta::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(184, 134, 11, 0.15) 0%, transparent 70%);
}

.cta h2 {
  color: var(--white);
  font-size: 2.4rem;
  margin-bottom: 16px;
}

.cta p {
  color: rgba(255, 255, 255, 0.6);
  max-width: 500px;
  margin: 0 auto 36px;
}

.cta .btn-primary {
  font-size: 0.9rem;
  padding: 16px 48px;
}

/* ============ FOOTER ============ */
.footer {
  background: var(--navy);
  color: rgba(255, 255, 255, 0.6);
  padding: 80px 0 0;
  border-top: 4px solid var(--gold);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 48px;
  padding-bottom: 60px;
}

.footer-brand img {
  height: 48px;
  margin-bottom: 16px;
}

.footer-brand p {
  font-size: 0.9rem;
  line-height: 1.8;
  margin-bottom: 20px;
}

.footer-social {
  display: flex;
  gap: 12px;
}

.footer-social a {
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.08);
  color: rgba(255, 255, 255, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.footer-social a:hover {
  background: var(--gold);
  color: var(--white);
}

.footer h4 {
  color: var(--white);
  font-size: 0.9rem;
  margin-bottom: 20px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.footer ul li {
  margin-bottom: 10px;
}

.footer ul li a {
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.85rem;
}

.footer ul li a:hover {
  color: var(--gold-light);
}

.footer-contact li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  margin-bottom: 12px;
  font-size: 0.85rem;
}

.footer-contact i {
  color: var(--gold);
  margin-top: 4px;
  width: 16px;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding: 24px 0;
  text-align: center;
  font-size: 0.8rem;
}

/* ============ ANIMATIONS ============ */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.animate-on-scroll {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}

.animate-on-scroll.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ============ BACK TO TOP ============ */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  z-index: 999;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--gold);
  color: var(--white);
  border: none;
  cursor: pointer;
  font-size: 1.1rem;
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  opacity: 0;
  visibility: hidden;
}

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

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

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

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

  .future-grid,
  .partners-grid {
    grid-template-columns: repeat(2, 1fr) !important;
  }

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

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

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

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .hamburger {
    display: flex;
  }

  .nav-links.active {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 80px;
    left: 0;
    right: 0;
    background: var(--white);
    padding: 24px;
    box-shadow: var(--shadow-lg);
    gap: 16px;
  }

  .hero {
    height: 80vh;
    min-height: 500px;
  }

  .hero-content {
    padding: 0 24px;
  }

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

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

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

  .section-padding {
    padding: 60px 0;
  }

  .services-grid,
  .courses-grid,
  .team-grid {
    grid-template-columns: 1fr;
  }

  .future-grid,
  .partners-grid {
    grid-template-columns: 1fr !important;
  }

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

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

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

  .stat-item {
    padding: 24px 16px;
  }

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

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

  .slider-dots {
    left: 24px;
  }
}