/* ============================================================
   VAST SERVICE — MAIN STYLES
   Variables · Typography · Base · Header · Footer · Utilities
   ============================================================ */

:root{
  /* === BRAND COLORS (từ logo) === */
  --teal-50:  #ccfbf1;
  --teal-100: #99f6e4;
  --teal-200: #5eead4;     /* Cyan sáng - glow, accent */
  --teal-300: #2dd4bf;
  --teal-400: #14b8a6;     /* PRIMARY - CTA, headings */
  --teal-500: #0d9488;
  --teal-600: #0d7377;     /* Logo deep tone */
  --teal-700: #115e59;
  --teal-800: #134e4a;
  --teal-900: #0a3a37;

  /* === BACKGROUND === */
  --bg-0: #050811;          /* Sâu nhất - body */
  --bg-1: #0a0f1c;          /* Card */
  --bg-2: #0f1729;          /* Card elevated */
  --bg-3: #161f33;          /* Hover */

  /* === LINES & BORDERS === */
  --line:        rgba(94, 234, 212, .08);
  --line-medium: rgba(94, 234, 212, .15);
  --line-strong: rgba(94, 234, 212, .28);

  /* === TEXT === */
  --text:      #e6f6f4;
  --text-mute: #8b9bb4;
  --text-dim:  #5a6a85;

  /* === SEMANTIC === */
  --success: #10b981;
  --warning: #f59e0b;     /* Gold accent — chỉ dùng cho badge "phổ biến" */
  --danger:  #ef4444;

  /* === GLOW SHADOWS === */
  --glow-sm: 0 0 12px rgba(20, 184, 166, .3);
  --glow-md: 0 0 24px rgba(20, 184, 166, .4);
  --glow-lg: 0 0 48px rgba(20, 184, 166, .5);
  --glow-cyan: 0 0 24px rgba(94, 234, 212, .5);

  /* === TIMING === */
  --ease: cubic-bezier(.16, 1, .3, 1);
  --ease-out: cubic-bezier(.4, 0, .2, 1);
}

/* ============================================================
   RESET & BASE
   ============================================================ */
*, *::before, *::after{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
html{
  scroll-behavior: smooth;
  scroll-padding-top: 90px;
  -webkit-text-size-adjust: 100%;
}
body{
  font-family: 'Be Vietnam Pro', system-ui, sans-serif;
  font-weight: 400;
  background: var(--bg-0);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}
img{ max-width: 100%; display: block; }
button{ font-family: inherit; cursor: pointer; }
a{ color: inherit; text-decoration: none; }

/* Vietnamese-friendly word breaking for headings */
h1, h2, h3, h4 {
  word-break: keep-all;
  overflow-wrap: break-word;
  hyphens: none;
}

/* ============================================================
   ATMOSPHERIC BACKGROUND
   ============================================================ */
body::before{
  content: '';
  position: fixed;
  inset: 0;
  background-image:
    radial-gradient(ellipse 80% 50% at 50% -10%, rgba(20, 184, 166, .12), transparent 60%),
    radial-gradient(ellipse 60% 40% at 100% 50%, rgba(13, 115, 119, .08), transparent 60%),
    radial-gradient(ellipse 60% 40% at 0% 100%, rgba(94, 234, 212, .06), transparent 60%);
  pointer-events: none;
  z-index: 0;
}
body::after{
  content: '';
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(94, 234, 212, .03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(94, 234, 212, .03) 1px, transparent 1px);
  background-size: 80px 80px;
  pointer-events: none;
  z-index: 0;
  mask-image: radial-gradient(ellipse 100% 80% at 50% 50%, #000 30%, transparent 85%);
  -webkit-mask-image: radial-gradient(ellipse 100% 80% at 50% 50%, #000 30%, transparent 85%);
}

main, header, footer, .floating-cta{
  position: relative;
  z-index: 1;
}

/* ============================================================
   TYPOGRAPHY
   ============================================================ */
h1, h2, h3, h4, h5{
  font-family: 'Saira', 'Be Vietnam Pro', system-ui, sans-serif;
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -.015em;
}
h1{ font-weight: 800; line-height: 1.15; }
h2{ line-height: 1.2; }
h3{ line-height: 1.3; }

.mono{
  font-family: 'JetBrains Mono', monospace;
  font-feature-settings: 'tnum' 1;
}

/* Eyebrow label (above section titles) */
.eyebrow{
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: .25em;
  color: var(--teal-200);
  text-transform: uppercase;
  padding: 8px 16px;
  border: 1px solid var(--line-strong);
  background: rgba(20, 184, 166, .04);
  clip-path: polygon(8px 0, 100% 0, calc(100% - 8px) 100%, 0 100%);
  white-space: nowrap;
}
.eyebrow::before{
  content: '';
  width: 6px;
  height: 6px;
  background: var(--teal-200);
  border-radius: 50%;
  box-shadow: 0 0 12px var(--teal-200);
  animation: pulse-dot 2s ease-in-out infinite;
}
@keyframes pulse-dot{
  0%, 100%{ opacity: 1; transform: scale(1); }
  50%{ opacity: .6; transform: scale(1.3); }
}

/* ============================================================
   LAYOUT
   ============================================================ */
.wrap{
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 24px;
}

section{
  padding: 120px 0;
  position: relative;
}

.section-head{
  text-align: center;
  margin-bottom: 72px;
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
}
.section-head h2{
  font-size: clamp(32px, 4.5vw, 52px);
  margin: 20px 0 18px;
  letter-spacing: -.02em;
}
.section-head p{
  font-size: 17px;
  color: var(--text-mute);
  line-height: 1.7;
}

.section-divider{
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  margin: 0 auto 8px;
  max-width: 280px;
}
.section-divider span{
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line-strong), transparent);
  flex: 1;
}
.section-divider svg{
  width: 18px;
  height: 18px;
  color: var(--teal-300);
  filter: drop-shadow(0 0 6px var(--teal-300));
}

/* ============================================================
   HEADER
   ============================================================ */
header{
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 18px 0;
  transition: all .4s var(--ease-out);
}
header.scrolled{
  background: rgba(5, 8, 17, .85);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--line);
  padding: 12px 0;
}
header .wrap{
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.logo{
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text);
  flex-shrink: 0;
}
.logo-mark{
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.logo-mark svg{
  width: 100%;
  height: 100%;
  filter: drop-shadow(0 0 12px rgba(20, 184, 166, .5));
}
.logo-text{
  display: flex;
  flex-direction: column;
  line-height: 1;
}
.logo-text strong{
  font-family: 'Saira', sans-serif;
  font-weight: 800;
  font-size: 18px;
  letter-spacing: .03em;
  color: var(--text);
}
.logo-text span{
  font-family: 'JetBrains Mono', monospace;
  font-size: 9px;
  letter-spacing: .25em;
  color: var(--teal-300);
  margin-top: 4px;
}

nav.main-nav{
  display: flex;
  gap: 4px;
  align-items: center;
}
nav.main-nav a{
  color: var(--text-mute);
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  padding: 9px 16px;
  transition: color .3s;
  position: relative;
}
nav.main-nav a:hover{ color: var(--teal-200); }
nav.main-nav a::after{
  content: '';
  position: absolute;
  bottom: 4px;
  left: 50%;
  width: 0;
  height: 1px;
  background: var(--teal-300);
  transition: all .3s;
  transform: translateX(-50%);
}
nav.main-nav a:hover::after{ width: 50%; }

.menu-toggle{
  display: none;
  background: none;
  border: 1px solid var(--line-strong);
  color: var(--teal-200);
  padding: 10px;
}
.menu-toggle:hover{ background: rgba(20, 184, 166, .08); }

/* ============================================================
   FOOTER
   ============================================================ */
footer{
  padding: 70px 0 30px;
  background: #030610;
  border-top: 1px solid var(--line);
  position: relative;
  overflow: hidden;
}
footer::before{
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--teal-400), transparent);
  opacity: .5;
}

.footer-grid{
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1fr;
  gap: 50px;
  margin-bottom: 50px;
}
.footer-col h4{
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--teal-300);
  text-transform: uppercase;
  margin-bottom: 20px;
  font-weight: 500;
}
.footer-col ul{ list-style: none; }
.footer-col li{ margin-bottom: 11px; }
.footer-col a{
  color: var(--text-mute);
  font-size: 14px;
  transition: color .3s, transform .3s;
  display: inline-block;
}
.footer-col a:hover{
  color: var(--teal-200);
  transform: translateX(3px);
}
.footer-col p{
  color: var(--text-mute);
  font-size: 14px;
  line-height: 1.75;
}

.footer-brand{
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}

.footer-bottom{
  padding-top: 30px;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  color: var(--text-dim);
  letter-spacing: .08em;
}

/* ============================================================
   FLOATING CTA
   ============================================================ */
.floating-cta{
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 90;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.float-btn{
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--teal-400);
  color: var(--bg-0);
  text-decoration: none;
  box-shadow: 0 8px 24px rgba(0, 0, 0, .4);
  transition: all .3s var(--ease);
  position: relative;
}
.float-btn::before{
  content: '';
  position: absolute;
  inset: -4px;
  border-radius: 50%;
  border: 2px solid var(--teal-400);
  opacity: 0;
  animation: pulse-ring 2s infinite;
}
.float-btn.zalo{
  background: #0068ff;
  color: #fff;
}
.float-btn.zalo::before{ border-color: #0068ff; }
.float-btn:hover{ transform: scale(1.1); }
.float-btn svg{ width: 26px; height: 26px; }

@keyframes pulse-ring{
  0%{ transform: scale(.95); opacity: .6; }
  100%{ transform: scale(1.4); opacity: 0; }
}

/* ============================================================
   SCROLL REVEAL
   ============================================================ */
.reveal{
  opacity: 0;
  transform: translateY(30px);
  transition: opacity .8s var(--ease), transform .8s var(--ease);
}
.reveal.in{
  opacity: 1;
  transform: translateY(0);
}
.reveal.delay-1{ transition-delay: .1s; }
.reveal.delay-2{ transition-delay: .2s; }
.reveal.delay-3{ transition-delay: .3s; }
.reveal.delay-4{ transition-delay: .4s; }
.reveal.delay-5{ transition-delay: .5s; }
.reveal.delay-6{ transition-delay: .6s; }

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

@media (max-width: 768px){
  section{ padding: 80px 0; }
  .section-head{ margin-bottom: 56px; }

  nav.main-nav{ display: none; }
  nav.main-nav.open{
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: rgba(5, 8, 17, .98);
    backdrop-filter: blur(20px);
    padding: 20px;
    border-top: 1px solid var(--line);
    gap: 0;
  }
  nav.main-nav.open a{
    padding: 14px 0;
    border-bottom: 1px solid var(--line);
    width: 100%;
  }
  .menu-toggle{ display: flex; }

  .footer-grid{ grid-template-columns: 1fr; gap: 36px; }
  .footer-bottom{ flex-direction: column; text-align: center; }
}