/* ===================================================
   HANG SƠN ĐOÒNG — style.css
   Premium UI with Glassmorphism, Animations & Nature Palette
   =================================================== */

/* ---------- RESET & DESIGN TOKENS ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* Nature-inspired palette */
  --clr-forest:      hsl(150, 38%, 16%);    /* #1a3a2a — xanh lục đậm */
  --clr-forest-deep: hsl(155, 42%, 10%);    /* #0f2218 — xanh rừng sâu */
  --clr-moss:        hsl(148, 35%, 27%);    /* #2d5a3d — rêu xanh */
  --clr-emerald:     hsl(152, 50%, 32%);    /* #298a52 — ngọc lục bảo */
  --clr-stone:       hsl(0, 0%, 24%);       /* #3d3d3d — xám đá */
  --clr-slate:       hsl(200, 6%, 12%);     /* #1d1f21 — đen xám */
  --clr-slate-warm:  hsl(160, 12%, 9%);     /* #141e19 — đen ấm */
  --clr-sand:        hsl(40, 55%, 58%);     /* #c9a050 — vàng cát */
  --clr-sand-lt:     hsl(42, 62%, 69%);     /* #e0ba6a — vàng nhạt */
  --clr-gold:        hsl(38, 70%, 55%);     /* #d4a237 — vàng hoàng gia */
  --clr-white:       hsl(35, 30%, 95%);     /* #f5f0e8 — trắng kem */
  --clr-mist:        hsla(35, 30%, 95%, 0.06);
  --clr-overlay:     hsla(155, 40%, 5%, 0.72);

  /* Glassmorphism */
  --glass-bg:        hsla(155, 30%, 12%, 0.45);
  --glass-border:    hsla(40, 55%, 58%, 0.12);
  --glass-blur:      20px;

  /* Typography */
  --ff-heading: 'Playfair Display', Georgia, serif;
  --ff-body:    'Inter', -apple-system, BlinkMacSystemFont, sans-serif;

  /* Spacing & Radius */
  --radius-sm:  10px;
  --radius-md:  16px;
  --radius-lg:  24px;
  --radius-xl:  32px;

  /* Shadows */
  --shadow-card:     0 8px 32px hsla(0, 0%, 0%, 0.35);
  --shadow-card-lg:  0 16px 48px hsla(0, 0%, 0%, 0.45);
  --shadow-glow:     0 0 40px hsla(40, 55%, 58%, 0.2);
  --shadow-glow-lg:  0 0 80px hsla(40, 55%, 58%, 0.15);

  /* Transitions */
  --ease-out:   cubic-bezier(0.16, 1, 0.3, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  --transition: 0.4s var(--ease-out);
  --transition-fast: 0.25s var(--ease-out);
}

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

body {
  font-family: var(--ff-body);
  background: var(--clr-slate-warm);
  color: var(--clr-white);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

/* ---------- SCROLLBAR ---------- */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--clr-slate-warm); }
::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, var(--clr-moss), var(--clr-sand));
  border-radius: 3px;
}

/* ---------- SELECTION ---------- */
::selection {
  background: hsla(40, 55%, 58%, 0.3);
  color: var(--clr-white);
}

/* ---------- GLASSMORPHISM UTILITY ---------- */
.glass-card {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
}

/* ---------- SCROLL ANIMATIONS ---------- */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(32px);
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
}

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

/* Stagger children delay */
.cards-grid .animate-on-scroll:nth-child(2) { transition-delay: 0.12s; }
.cards-grid .animate-on-scroll:nth-child(3) { transition-delay: 0.24s; }
.intro-stats .animate-on-scroll:nth-child(2) { transition-delay: 0.08s; }
.intro-stats .animate-on-scroll:nth-child(3) { transition-delay: 0.16s; }
.intro-stats .animate-on-scroll:nth-child(4) { transition-delay: 0.24s; }
.timeline-item:nth-child(3) .animate-on-scroll { transition-delay: 0.1s; }
.timeline-item:nth-child(4) .animate-on-scroll { transition-delay: 0.2s; }
.gallery-grid .animate-on-scroll:nth-child(2) { transition-delay: 0.06s; }
.gallery-grid .animate-on-scroll:nth-child(3) { transition-delay: 0.12s; }
.gallery-grid .animate-on-scroll:nth-child(4) { transition-delay: 0.18s; }
.gallery-grid .animate-on-scroll:nth-child(5) { transition-delay: 0.24s; }
.gallery-grid .animate-on-scroll:nth-child(6) { transition-delay: 0.30s; }


/* =============================================
   HEADER / NAV — Glassmorphism Fixed
   ============================================= */
header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  padding: 1rem 2.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: hsla(155, 30%, 8%, 0.4);
  backdrop-filter: blur(24px) saturate(1.2);
  -webkit-backdrop-filter: blur(24px) saturate(1.2);
  border-bottom: 1px solid hsla(40, 55%, 58%, 0.08);
  transition: all var(--transition);
}

header.scrolled {
  padding: 0.7rem 2.5rem;
  background: hsla(155, 30%, 8%, 0.85);
  border-bottom-color: hsla(40, 55%, 58%, 0.15);
  box-shadow: 0 4px 30px hsla(0, 0%, 0%, 0.3);
}

.nav-logo {
  font-family: var(--ff-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--clr-sand);
  letter-spacing: 0.04em;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: color var(--transition-fast);
}

.nav-logo:hover { color: var(--clr-sand-lt); }

.logo-icon {
  color: var(--clr-sand);
  flex-shrink: 0;
}

.nav-logo span {
  color: var(--clr-white);
  opacity: 0.7;
  font-weight: 400;
}

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

nav ul li a {
  color: var(--clr-white);
  text-decoration: none;
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  position: relative;
  opacity: 0.75;
  transition: opacity var(--transition-fast), color var(--transition-fast);
  padding: 0.3rem 0;
}

nav ul li a::after {
  content: '';
  position: absolute;
  left: 0; bottom: -2px;
  width: 0; height: 2px;
  background: linear-gradient(90deg, var(--clr-sand), var(--clr-sand-lt));
  border-radius: 1px;
  transition: width var(--transition);
}

nav ul li a:hover,
nav ul li a.active {
  opacity: 1;
  color: var(--clr-sand);
}

nav ul li a:hover::after,
nav ul li a.active::after {
  width: 100%;
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  z-index: 1001;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--clr-white);
  border-radius: 2px;
  transition: all 0.3s ease;
}

.hamburger.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}
.hamburger.active span:nth-child(2) {
  opacity: 0;
}
.hamburger.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* Mobile overlay menu */
.mobile-menu-overlay {
  position: fixed;
  inset: 0;
  z-index: 999;
  background: hsla(155, 30%, 5%, 0.95);
  backdrop-filter: blur(30px);
  -webkit-backdrop-filter: blur(30px);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s ease;
}

.mobile-menu-overlay.open {
  opacity: 1;
  pointer-events: all;
}

.mobile-nav ul {
  list-style: none;
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.mobile-nav a {
  color: var(--clr-white);
  text-decoration: none;
  font-family: var(--ff-heading);
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  transition: color var(--transition-fast);
}

.mobile-nav a:hover,
.mobile-nav a.active {
  color: var(--clr-sand);
}


/* =============================================
   HERO SECTION — Cinematic
   ============================================= */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: -20px;
  background:
    url('https://images.unsplash.com/photo-1506905925346-21bda4d32df4?w=1920&q=80') center/cover no-repeat;
  will-change: transform;
  filter: brightness(0.6) saturate(1.1);
}

/* Vignette overlay */
.hero-vignette {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at center, transparent 30%, hsla(155, 40%, 5%, 0.6) 100%),
    linear-gradient(to bottom, hsla(155, 40%, 5%, 0.15) 0%, hsla(155, 40%, 5%, 0.5) 50%, hsla(155, 40%, 5%, 0.85) 100%);
  z-index: 1;
}

/* Particle layer */
.hero-particles {
  position: absolute;
  inset: 0;
  z-index: 1;
  background-image:
    radial-gradient(circle, hsla(40, 55%, 58%, 0.12) 1px, transparent 1px);
  background-size: 80px 80px;
  animation: particleShift 12s linear infinite;
  opacity: 0.4;
}

@keyframes particleShift {
  from { background-position: 0 0; }
  to   { background-position: 80px 80px; }
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 900px;
  padding: 0 1.5rem;
}

.hero-content .animate-on-scroll {
  opacity: 0;
  transform: translateY(40px);
}

.hero-content .animate-on-scroll.visible {
  animation: heroFadeUp 1s var(--ease-out) forwards;
}

.hero-content .animate-on-scroll:nth-child(1) { animation-delay: 0.2s; }
.hero-content .animate-on-scroll:nth-child(2) { animation-delay: 0.4s; }
.hero-content .animate-on-scroll:nth-child(3) { animation-delay: 0.6s; }
.hero-content .animate-on-scroll:nth-child(4) { animation-delay: 0.8s; }

@keyframes heroFadeUp {
  from { opacity: 0; transform: translateY(40px); }
  to   { opacity: 1; transform: translateY(0); }
}

.hero-badge {
  display: inline-block;
  background: hsla(40, 55%, 58%, 0.12);
  border: 1px solid hsla(40, 55%, 58%, 0.35);
  color: var(--clr-sand-lt);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  padding: 0.5rem 1.4rem;
  border-radius: 999px;
  margin-bottom: 2rem;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.hero h1 {
  font-family: var(--ff-heading);
  font-size: clamp(2.6rem, 7vw, 5.5rem);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.02em;
  margin-bottom: 1.6rem;
  text-shadow: 0 4px 40px hsla(0, 0%, 0%, 0.4);
}

.hero h1 .highlight {
  background: linear-gradient(135deg, var(--clr-sand) 0%, var(--clr-sand-lt) 50%, var(--clr-gold) 100%);
  background-size: 200% 200%;
  animation: shimmer 4s ease-in-out infinite;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

@keyframes shimmer {
  0%, 100% { background-position: 0% 50%; }
  50%      { background-position: 100% 50%; }
}

.hero-slogan {
  font-size: clamp(1rem, 2vw, 1.2rem);
  font-weight: 300;
  color: hsla(35, 30%, 95%, 0.8);
  max-width: 620px;
  margin: 0 auto 2.8rem;
  line-height: 1.85;
}

.hero-actions {
  display: flex;
  gap: 1.2rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* Primary button */
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  background: linear-gradient(135deg, var(--clr-sand) 0%, var(--clr-gold) 100%);
  color: var(--clr-slate);
  font-weight: 700;
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.95rem 2.4rem;
  border-radius: 999px;
  text-decoration: none;
  border: none;
  cursor: pointer;
  box-shadow: 0 4px 24px hsla(40, 55%, 58%, 0.35);
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.btn-primary::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent, hsla(0, 0%, 100%, 0.25), transparent);
  transform: translateX(-100%);
  transition: transform 0.6s ease;
}

.btn-primary:hover {
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 8px 40px hsla(40, 55%, 58%, 0.5);
}

.btn-primary:hover::before {
  transform: translateX(100%);
}

/* Outline button */
.btn-outline {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  background: transparent;
  color: var(--clr-white);
  font-weight: 600;
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.95rem 2.4rem;
  border-radius: 999px;
  text-decoration: none;
  border: 1.5px solid hsla(35, 30%, 95%, 0.35);
  cursor: pointer;
  transition: all var(--transition);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.btn-outline:hover {
  background: hsla(35, 30%, 95%, 0.1);
  border-color: var(--clr-white);
  transform: translateY(-3px);
  box-shadow: 0 4px 20px hsla(0, 0%, 100%, 0.1);
}

/* Scroll indicator */
.scroll-down {
  position: absolute;
  bottom: 2.5rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.8rem;
  text-decoration: none;
  z-index: 2;
}

.scroll-indicator {
  width: 24px;
  height: 40px;
  border: 2px solid hsla(35, 30%, 95%, 0.3);
  border-radius: 12px;
  position: relative;
}

.scroll-dot {
  width: 4px;
  height: 8px;
  background: var(--clr-sand);
  border-radius: 2px;
  position: absolute;
  top: 6px;
  left: 50%;
  transform: translateX(-50%);
  animation: scrollBounce 2s ease-in-out infinite;
}

@keyframes scrollBounce {
  0%, 100% { top: 6px; opacity: 1; }
  50%      { top: 22px; opacity: 0.3; }
}

.scroll-down span {
  color: hsla(35, 30%, 95%, 0.4);
  font-size: 0.65rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}


/* =============================================
   SECTION CHUNG
   ============================================= */
section {
  padding: 8rem 1.5rem;
  position: relative;
}

.container {
  max-width: 1140px;
  margin: 0 auto;
}

.section-tag {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--clr-sand);
  margin-bottom: 1rem;
  position: relative;
  padding-left: 2rem;
}

.section-tag::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 1.2rem;
  height: 2px;
  background: linear-gradient(90deg, var(--clr-sand), transparent);
}

.section-title {
  font-family: var(--ff-heading);
  font-size: clamp(2rem, 4.5vw, 3.2rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--clr-white);
  margin-bottom: 1.6rem;
}

.section-title .accent { color: var(--clr-sand); }

/* Decorative divider */
.divider {
  width: 64px;
  height: 3px;
  background: linear-gradient(90deg, var(--clr-sand), var(--clr-moss), transparent);
  border-radius: 2px;
  margin-bottom: 2rem;
}


/* =============================================
   GIỚI THIỆU (INTRO)
   ============================================= */
.intro {
  background:
    radial-gradient(ellipse at 20% 80%, hsla(150, 40%, 15%, 0.4) 0%, transparent 50%),
    linear-gradient(160deg, var(--clr-forest) 0%, var(--clr-forest-deep) 100%);
}

.intro-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 5rem;
  align-items: center;
}

.intro-text p {
  color: hsla(35, 30%, 95%, 0.78);
  font-size: 1.02rem;
  line-height: 1.9;
  margin-bottom: 1.2rem;
}

.intro-text p:last-of-type { margin-bottom: 2.5rem; }

.intro-text p strong {
  color: var(--clr-sand-lt);
  font-weight: 600;
}

.intro-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
}

.stat-card {
  border-radius: var(--radius-md);
  padding: 1.4rem 1.2rem;
  text-align: center;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.stat-card::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: linear-gradient(135deg, hsla(40, 55%, 58%, 0.08), transparent);
  opacity: 0;
  transition: opacity var(--transition);
}

.stat-card:hover {
  border-color: hsla(40, 55%, 58%, 0.4);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}

.stat-card:hover::after { opacity: 1; }

.stat-icon { font-size: 1.8rem; margin-bottom: 0.3rem; }

.stat-number {
  font-family: var(--ff-heading);
  font-size: 2.2rem;
  font-weight: 900;
  color: var(--clr-sand);
  line-height: 1;
}

.stat-unit {
  font-size: 1rem;
  font-weight: 600;
  color: hsla(40, 55%, 58%, 0.7);
  margin-left: 0.1rem;
}

.stat-label {
  font-size: 0.72rem;
  font-weight: 500;
  color: hsla(35, 30%, 95%, 0.55);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-top: 0.4rem;
}

/* Visual column */
.intro-visual {
  position: relative;
}

.intro-img-wrap {
  position: relative;
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-card-lg);
}

.intro-img-wrap img {
  width: 100%;
  height: 500px;
  object-fit: cover;
  display: block;
  transition: transform 0.8s var(--ease-out);
}

.intro-img-wrap:hover img { transform: scale(1.05); }

/* Floating badge on image */
.img-badge {
  position: absolute;
  bottom: 1.5rem;
  left: 1.5rem;
  border-radius: var(--radius-md);
  padding: 0.9rem 1.3rem;
  display: flex;
  align-items: center;
  gap: 0.8rem;
  transition: transform var(--transition-fast);
}

.intro-img-wrap:hover .img-badge {
  transform: translateY(-4px);
}

.img-badge-icon { font-size: 1.5rem; }

.img-badge-text {
  font-size: 0.78rem;
  color: var(--clr-white);
  font-weight: 500;
  line-height: 1.4;
}

.img-badge-text strong {
  display: block;
  color: var(--clr-sand);
  font-size: 0.88rem;
}

/* Floating decorative shapes */
.floating-shape {
  position: absolute;
  border-radius: 50%;
  pointer-events: none;
}

.shape-1 {
  width: 200px;
  height: 200px;
  top: -40px;
  right: -40px;
  background: radial-gradient(circle, hsla(40, 55%, 58%, 0.06), transparent 70%);
  animation: floatShape 8s ease-in-out infinite;
}

.shape-2 {
  width: 140px;
  height: 140px;
  bottom: -30px;
  left: -30px;
  background: radial-gradient(circle, hsla(150, 40%, 30%, 0.08), transparent 70%);
  animation: floatShape 10s ease-in-out infinite reverse;
}

@keyframes floatShape {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50%      { transform: translate(15px, -20px) scale(1.1); }
}


/* =============================================
   HIGHLIGHTS — Glassmorphism Cards
   ============================================= */
.highlights {
  background:
    radial-gradient(ellipse at 70% 20%, hsla(150, 30%, 15%, 0.3) 0%, transparent 50%),
    var(--clr-slate);
}

.highlights-header {
  text-align: center;
  max-width: 640px;
  margin: 0 auto 4.5rem;
}

.highlights-header .divider { margin: 0 auto 2rem; }

.highlights-subtitle {
  color: hsla(35, 30%, 95%, 0.6);
  font-size: 1rem;
  line-height: 1.8;
}

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

.highlight-card {
  border-radius: var(--radius-lg);
  padding: 2.6rem 2.2rem;
  position: relative;
  overflow: hidden;
  transition: all var(--transition);
  cursor: default;
}

/* Glow effect on hover */
.card-glow {
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at center, hsla(40, 55%, 58%, 0.05), transparent 50%);
  opacity: 0;
  transition: opacity 0.6s ease;
  pointer-events: none;
}

.highlight-card:hover .card-glow { opacity: 1; }

/* Top accent line */
.highlight-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--clr-sand), var(--clr-emerald), transparent);
  opacity: 0;
  transition: opacity var(--transition);
}

.highlight-card:hover {
  transform: translateY(-8px);
  border-color: hsla(40, 55%, 58%, 0.3);
  box-shadow: var(--shadow-card-lg), var(--shadow-glow);
}

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

.card-icon {
  font-size: 3rem;
  margin-bottom: 1.4rem;
  display: block;
  filter: drop-shadow(0 4px 16px hsla(40, 55%, 58%, 0.3));
  transition: transform 0.4s var(--ease-spring);
}

.highlight-card:hover .card-icon {
  transform: scale(1.1) translateY(-4px);
}

.card-tag {
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--clr-sand);
  margin-bottom: 0.8rem;
}

.card-title {
  font-family: var(--ff-heading);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--clr-white);
  margin-bottom: 1rem;
  line-height: 1.3;
}

.card-desc {
  color: hsla(35, 30%, 95%, 0.65);
  font-size: 0.92rem;
  line-height: 1.8;
}

.card-metric {
  margin-top: 1.8rem;
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
  padding-top: 1.2rem;
  border-top: 1px solid hsla(40, 55%, 58%, 0.1);
}

.metric-value {
  font-family: var(--ff-heading);
  font-size: 2rem;
  font-weight: 900;
  color: var(--clr-sand);
}

.metric-unit {
  font-size: 0.8rem;
  color: hsla(35, 30%, 95%, 0.45);
  font-weight: 500;
}

.card-bg-num {
  position: absolute;
  right: 1rem;
  bottom: 0.5rem;
  font-family: var(--ff-heading);
  font-size: 6rem;
  font-weight: 900;
  color: hsla(40, 55%, 58%, 0.04);
  line-height: 1;
  user-select: none;
  pointer-events: none;
  transition: color var(--transition);
}

.highlight-card:hover .card-bg-num {
  color: hsla(40, 55%, 58%, 0.08);
}


/* =============================================
   TIMELINE — Hành Trình Khám Phá
   ============================================= */
.timeline-section {
  background:
    radial-gradient(ellipse at 80% 50%, hsla(150, 40%, 12%, 0.3) 0%, transparent 50%),
    linear-gradient(180deg, var(--clr-forest-deep) 0%, var(--clr-slate-warm) 100%);
}

.timeline-header {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 4rem;
}

.timeline-header .divider { margin: 0 auto 2rem; }

.timeline {
  position: relative;
  max-width: 700px;
  margin: 0 auto;
  padding-left: 3rem;
}

.timeline-line {
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--clr-sand), var(--clr-moss), transparent);
}

.timeline-item {
  position: relative;
  margin-bottom: 3rem;
}

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

.timeline-dot {
  position: absolute;
  left: -3rem;
  top: 1.5rem;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--clr-sand);
  border: 3px solid var(--clr-forest-deep);
  transform: translateX(-50%);
  left: -3.05rem;
  box-shadow: 0 0 12px hsla(40, 55%, 58%, 0.3);
  z-index: 1;
}

.timeline-content {
  border-radius: var(--radius-md);
  padding: 2rem 2.2rem;
  transition: all var(--transition);
}

.timeline-content:hover {
  transform: translateX(8px);
  border-color: hsla(40, 55%, 58%, 0.3);
  box-shadow: var(--shadow-glow);
}

.timeline-year {
  font-family: var(--ff-heading);
  font-size: 2rem;
  font-weight: 900;
  color: var(--clr-sand);
  margin-bottom: 0.3rem;
}

.timeline-content h3 {
  font-family: var(--ff-heading);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--clr-white);
  margin-bottom: 0.8rem;
}

.timeline-content p {
  color: hsla(35, 30%, 95%, 0.65);
  font-size: 0.92rem;
  line-height: 1.8;
}


/* =============================================
   GALLERY
   ============================================= */
.gallery {
  background:
    radial-gradient(ellipse at 30% 80%, hsla(150, 40%, 15%, 0.2) 0%, transparent 50%),
    linear-gradient(180deg, var(--clr-slate-warm) 0%, var(--clr-forest) 100%);
  padding-bottom: 8rem;
}

.gallery-header {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 4rem;
}

.gallery-header .divider { margin: 0 auto 2rem; }

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: 240px 240px;
  gap: 1rem;
}

.gallery-item {
  border-radius: var(--radius-md);
  overflow: hidden;
  position: relative;
  cursor: pointer;
}

.gallery-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transition: transform 0.6s var(--ease-out), filter 0.5s ease;
  filter: brightness(0.8) saturate(0.9);
}

.gallery-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, hsla(0, 0%, 0%, 0.6) 0%, transparent 50%);
  display: flex;
  align-items: flex-end;
  padding: 1.2rem;
  opacity: 0;
  transition: opacity 0.4s ease;
}

.gallery-overlay span {
  color: var(--clr-white);
  font-size: 0.85rem;
  font-weight: 600;
  transform: translateY(10px);
  transition: transform 0.4s var(--ease-out);
}

.gallery-item:hover img {
  transform: scale(1.08);
  filter: brightness(1) saturate(1.15);
}

.gallery-item:hover .gallery-overlay {
  opacity: 1;
}

.gallery-item:hover .gallery-overlay span {
  transform: translateY(0);
}

/* Large items span 2 columns */
.gallery-item.large { grid-column: span 2; }


/* =============================================
   CTA BANNER
   ============================================= */
.cta-banner {
  position: relative;
  padding: 8rem 1.5rem;
  text-align: center;
  overflow: hidden;
}

.cta-banner-bg {
  position: absolute;
  inset: 0;
  background:
    url('https://images.unsplash.com/photo-1559494007-9f5847c49d94?w=1920&q=80') center/cover no-repeat;
  filter: brightness(0.35) saturate(1.2);
}

.cta-banner::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at center, transparent 20%, hsla(155, 40%, 5%, 0.7) 100%),
    linear-gradient(to bottom, hsla(155, 40%, 5%, 0.3), hsla(155, 40%, 5%, 0.6));
  z-index: 1;
}

.cta-floating-particles {
  position: absolute;
  inset: 0;
  z-index: 1;
  background-image:
    radial-gradient(circle, hsla(40, 55%, 58%, 0.08) 1px, transparent 1px);
  background-size: 50px 50px;
  animation: particleShift 15s linear infinite;
}

.cta-content {
  position: relative;
  z-index: 2;
  max-width: 720px;
  margin: 0 auto;
}

.cta-content .section-tag::before { display: none; }
.cta-content .section-tag { padding-left: 0; }
.cta-content .section-title { margin-bottom: 1.2rem; }

.cta-content p {
  color: hsla(35, 30%, 95%, 0.75);
  font-size: 1.05rem;
  margin-bottom: 2.8rem;
  line-height: 1.85;
}


/* =============================================
   FOOTER
   ============================================= */
footer {
  background: hsl(160, 15%, 5%);
  border-top: 1px solid hsla(40, 55%, 58%, 0.08);
}

.footer-inner {
  max-width: 1140px;
  margin: 0 auto;
  padding: 4rem 1.5rem 2.5rem;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 3rem;
}

.footer-brand { }

.footer-logo {
  font-family: var(--ff-heading);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--clr-sand);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.8rem;
}

.footer-logo .logo-icon { color: var(--clr-sand); }

.footer-desc {
  color: hsla(35, 30%, 95%, 0.4);
  font-size: 0.88rem;
  line-height: 1.7;
  max-width: 300px;
}

.footer-nav {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.footer-nav h4 {
  font-family: var(--ff-heading);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--clr-white);
  margin-bottom: 0.5rem;
  letter-spacing: 0.03em;
}

.footer-nav a {
  color: hsla(35, 30%, 95%, 0.45);
  text-decoration: none;
  font-size: 0.85rem;
  transition: color var(--transition-fast), transform var(--transition-fast);
  display: inline-block;
}

.footer-nav a:hover {
  color: var(--clr-sand);
  transform: translateX(4px);
}

.footer-bottom {
  border-top: 1px solid hsla(40, 55%, 58%, 0.06);
  padding: 1.5rem;
  text-align: center;
}

.footer-copy {
  font-size: 0.78rem;
  color: hsla(35, 30%, 95%, 0.3);
}


/* =============================================
   BACK TO TOP BUTTON
   ============================================= */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px solid hsla(40, 55%, 58%, 0.2);
  background: hsla(155, 30%, 12%, 0.7);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  color: var(--clr-sand);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transform: translateY(20px);
  pointer-events: none;
  transition: all var(--transition);
  z-index: 900;
}

.back-to-top.show {
  opacity: 1;
  transform: translateY(0);
  pointer-events: all;
}

.back-to-top:hover {
  background: hsla(155, 30%, 12%, 0.9);
  border-color: var(--clr-sand);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}


/* =============================================
   RESPONSIVE — TABLET
   ============================================= */
@media (max-width: 900px) {
  header { padding: 1rem 1.5rem; }
  header.scrolled { padding: 0.7rem 1.5rem; }

  #main-nav { display: none; }
  .hamburger { display: flex; }

  .intro-grid {
    grid-template-columns: 1fr;
    gap: 3.5rem;
  }
  .intro-visual { order: -1; }
  .intro-img-wrap img { height: 360px; }

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

  .gallery-grid {
    grid-template-columns: 1fr 1fr;
    grid-template-rows: auto;
  }
  .gallery-item { min-height: 200px; }
  .gallery-item.large { grid-column: span 2; }

  .footer-inner {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 2rem;
  }
  .footer-desc { max-width: none; margin: 0 auto; }
  .footer-nav { align-items: center; }

  .timeline { padding-left: 2.5rem; }
  .timeline-dot { left: -2.55rem; }
}


/* =============================================
   RESPONSIVE — ĐIỆN THOẠI
   ============================================= */
@media (max-width: 600px) {
  header { padding: 0.8rem 1rem; }
  header.scrolled { padding: 0.6rem 1rem; }

  .hero h1 { font-size: 2.2rem; }
  .hero-slogan { font-size: 0.95rem; }
  .hero-badge { font-size: 0.65rem; padding: 0.4rem 1rem; }

  section { padding: 5rem 1rem; }

  .cards-grid { grid-template-columns: 1fr; }
  .highlight-card { padding: 2rem 1.6rem; }

  .intro-stats { grid-template-columns: 1fr 1fr; gap: 0.8rem; }
  .stat-card { padding: 1.2rem 1rem; }
  .stat-number { font-size: 1.8rem; }

  .gallery-grid {
    grid-template-columns: 1fr;
    grid-template-rows: auto;
  }
  .gallery-item { min-height: 180px; }
  .gallery-item.large { grid-column: span 1; }

  .timeline { padding-left: 2rem; }
  .timeline-dot { left: -2.05rem; width: 12px; height: 12px; }
  .timeline-content { padding: 1.5rem 1.4rem; }
  .timeline-year { font-size: 1.6rem; }

  .btn-primary, .btn-outline {
    padding: 0.85rem 1.8rem;
    font-size: 0.8rem;
  }

  .scroll-down { bottom: 1.5rem; }
  .back-to-top { bottom: 1.2rem; right: 1.2rem; width: 42px; height: 42px; }

  .floating-shape { display: none; }
}

/* Small phones */
@media (max-width: 380px) {
  .hero h1 { font-size: 1.9rem; }
  .hero-actions { flex-direction: column; align-items: center; }
  .intro-stats { grid-template-columns: 1fr; }
}