/*
 * platform.css — TVT / toilatung.com Design System
 * Shared across all pages. Load BEFORE Tailwind.
 */

/* ══════════════════════════════════════════
   DESIGN TOKENS
══════════════════════════════════════════ */
:root {
  /* Backgrounds */
  --bg:           #000000;
  --surface:      #0a0a0a;
  --panel:        #111111;
  --line:         rgba(255, 255, 255, 0.08);
  --line-hover:   rgba(255, 255, 255, 0.16);

  /* Text */
  --text-1:       #f5f5f7;
  --text-2:       #a1a1a6;
  --text-3:       #6e6e73;

  /* Brand colours */
  --brand-red:    #ff375f;
  --brand-red-l:  #ff6380;
  --brand-red-g:  rgba(255, 55, 95, 0.28);

  --brand-indigo: #7b61ff;
  --brand-indigo-g: rgba(123, 97, 255, 0.24);

  --brand-pink:   #f472b6;
  --brand-pink-g: rgba(244, 114, 182, 0.22);

  --brand-emerald: #30d158;
  --brand-amber:   #ffd60a;
  --brand-sky:     #2997ff;
  --brand-sky-g:   rgba(41, 151, 255, 0.28);

  /* Short aliases — match existing page inline-style usage */
  --red:        var(--brand-red);
  --red-light:  var(--brand-red-l);
  --red-glow:   var(--brand-red-g);
  --indigo:     var(--brand-indigo);
  --indigo-glow:var(--brand-indigo-g);
  --pink:       var(--brand-pink);
  --pink-glow:  var(--brand-pink-g);
  --emerald:    var(--brand-emerald);
  --amber:      var(--brand-amber);
  --sky:        var(--brand-sky);
  --sky-glow:   var(--brand-sky-g);

  /* Spacing scale */
  --section-y:   6rem;   /* py-24 */
  --card-p:      2rem;   /* p-8   */

  /* Radius */
  --r-card:  20px;
  --r-btn:   14px;
  --r-badge: 99px;

  /* Transitions */
  --ease-spring: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-std:    cubic-bezier(0.4, 0, 0.2, 1);
}

/* ══════════════════════════════════════════
   RESET & BASE
══════════════════════════════════════════ */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  background: var(--bg);
  color: var(--text-2);
}

/* ══════════════════════════════════════════
   TYPOGRAPHY
══════════════════════════════════════════ */
.text-hero {
  letter-spacing: -0.04em;
  line-height: 1.04;
}
.text-label {
  font-size: 0.625rem;   /* 10px */
  font-weight: 900;
  letter-spacing: 0.3em;
  text-transform: uppercase;
}

/* Gradient texts */
.gradient-text {
  background: linear-gradient(90deg, var(--brand-red), var(--brand-indigo), var(--brand-sky));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.gradient-indigo {
  background: linear-gradient(90deg, var(--brand-indigo), var(--brand-emerald));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.gradient-pink {
  background: linear-gradient(90deg, var(--brand-pink), var(--brand-amber));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.gradient-sky {
  background: linear-gradient(90deg, var(--brand-sky), var(--brand-indigo));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.gradient-amber {
  background: linear-gradient(90deg, var(--brand-amber), #f59e0b);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.gradient-emerald {
  background: linear-gradient(90deg, var(--brand-emerald), #10b981);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ══════════════════════════════════════════
   GLASS CARD
══════════════════════════════════════════ */
.glass {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--r-card);
  position: relative;
  overflow: hidden;
}
.glass::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(
    circle at var(--mx, 50%) var(--my, 50%),
    rgba(255,255,255,.035) 0%, transparent 60%
  );
  opacity: 0;
  transition: opacity .3s;
  pointer-events: none;
}
.glass:hover::before { opacity: 1; }

/* ══════════════════════════════════════════
   CARD VARIANTS
══════════════════════════════════════════ */
.card-hover {
  transition:
    transform .3s var(--ease-spring),
    border-color .3s ease,
    background .3s ease;
}
.card-hover:hover {
  transform: translateY(-3px);
  border-color: var(--line-hover);
  background: #161616;
}

.program-card {
  transition:
    transform .3s var(--ease-spring),
    border-color .3s ease,
    box-shadow .3s ease;
}
.program-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 0 48px rgba(255,255,255,.04);
}

/* ══════════════════════════════════════════
   BUTTONS
══════════════════════════════════════════ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 1.75rem;
  font-weight: 900;
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border-radius: var(--r-btn);
  border: none;
  cursor: pointer;
  transition: opacity .2s ease, transform .2s var(--ease-spring);
  text-decoration: none;
}
.btn:hover  { opacity: .88; transform: translateY(-1px); }
.btn:active { transform: scale(.97); }

.btn-red {
  background: var(--brand-red);
  color: #fff;
  box-shadow: 0 8px 30px var(--brand-red-g);
}
.btn-red:hover { background: var(--brand-red-l); }

.btn-indigo {
  background: var(--brand-indigo);
  color: #fff;
  box-shadow: 0 8px 30px var(--brand-indigo-g);
}

.btn-ghost {
  background: transparent;
  color: var(--text-1);
  border: 1px solid var(--line);
}
.btn-ghost:hover { border-color: var(--line-hover); }

.btn-zalo {
  background: #0068ff;
  color: #fff;
  box-shadow: 0 8px 30px rgba(0,104,255,0.3);
}
.btn-zalo:hover { background: #0052cc; }

/* ══════════════════════════════════════════
   BADGES
══════════════════════════════════════════ */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.3rem 0.75rem;
  border-radius: var(--r-badge);
  font-size: 0.625rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}
.badge-red    { background: rgba(255,55,95,.1);   color: #ff8f8f;  border: 1px solid rgba(255,55,95,.2);   }
.badge-indigo { background: rgba(123,97,255,.1);  color: #c7d2fe;  border: 1px solid rgba(123,97,255,.2);  }
.badge-pink   { background: rgba(244,114,182,.1); color: #f9a8d4;  border: 1px solid rgba(244,114,182,.2); }
.badge-sky    { background: rgba(41,151,255,.12); color: #93c5fd;  border: 1px solid rgba(41,151,255,.25); }
.badge-amber  { background: rgba(245,158,11,.1);  color: #fcd34d;  border: 1px solid rgba(245,158,11,.2);  }
.badge-emerald{ background: rgba(52,211,153,.1);  color: #86efac;  border: 1px solid rgba(52,211,153,.2);  }
.badge-free   { background: rgba(52,211,153,.1);  color: #6ee7b7;  border: 1px solid rgba(52,211,153,.2);  }

/* ══════════════════════════════════════════
   ANIMATIONS
══════════════════════════════════════════ */
.badge-pulse { animation: pulse 2s cubic-bezier(0.4,0,0.6,1) infinite; }
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50%       { opacity: .7; }
}

/* Scroll Reveal */
.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity .9s var(--ease-spring), transform .9s var(--ease-spring);
}
.reveal.visible { opacity: 1; transform: none; }

.reveal-left {
  opacity: 0;
  transform: translateX(-32px);
  transition: opacity .9s var(--ease-spring), transform .9s var(--ease-spring);
}
.reveal-left.visible { opacity: 1; transform: none; }

.reveal-right {
  opacity: 0;
  transform: translateX(32px);
  transition: opacity .9s var(--ease-spring), transform .9s var(--ease-spring);
}
.reveal-right.visible { opacity: 1; transform: none; }

.delay-1 { transition-delay: .1s; }
.delay-2 { transition-delay: .2s; }
.delay-3 { transition-delay: .3s; }
.delay-4 { transition-delay: .4s; }
.delay-5 { transition-delay: .5s; }

/* ══════════════════════════════════════════
   NAV — Apple-style transparent → frosted
══════════════════════════════════════════ */
nav#main-nav {
  position: fixed;
  top: 0; width: 100%; z-index: 50;
  background: rgba(0,0,0,0);
  backdrop-filter: blur(0px);
  border-bottom: 1px solid transparent;
  transition: background .45s ease, backdrop-filter .45s ease, border-color .45s ease;
}
nav#main-nav.nav-scrolled {
  background: rgba(0,0,0,.78);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-color: var(--line);
}

/* ══════════════════════════════════════════
   MOBILE DRAWER
══════════════════════════════════════════ */
#mobileDrawer {
  position: fixed;
  top: 0; right: 0; bottom: 0;
  width: 280px;
  background: #0a0a0a;
  border-left: 1px solid var(--line);
  z-index: 200;
  transform: translateX(100%);
  transition: transform .3s var(--ease-std);
  overflow-y: auto;
}
#mobileDrawer.open { transform: translateX(0); }

#drawerOverlay {
  position: fixed; inset: 0;
  background: rgba(0,0,0,.72);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  z-index: 199;
  opacity: 0; pointer-events: none;
  transition: opacity .3s ease;
}
#drawerOverlay.open { opacity: 1; pointer-events: all; }

/* ══════════════════════════════════════════
   HAMBURGER
══════════════════════════════════════════ */
.hamburger-line {
  display: block; width: 22px; height: 2px;
  background: rgba(255,255,255,.7); border-radius: 2px;
  transition: all .3s ease;
  transform-origin: center;
}
.hamburger.active .hamburger-line:nth-child(1) { transform: translateY(8px) rotate(45deg); }
.hamburger.active .hamburger-line:nth-child(2) { opacity: 0; transform: scaleX(0); }
.hamburger.active .hamburger-line:nth-child(3) { transform: translateY(-8px) rotate(-45deg); }

/* ══════════════════════════════════════════
   GRAIN TEXTURE
══════════════════════════════════════════ */
body::after {
  content: ''; position: fixed; inset: 0; pointer-events: none; z-index: 9998;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='1'/%3E%3C/svg%3E");
  opacity: .016;
}

/* ══════════════════════════════════════════
   HERO GLOW BACKGROUND
══════════════════════════════════════════ */
.hero-glow {
  background:
    radial-gradient(ellipse 80% 60% at 50% -10%, rgba(123,97,255,.16)   0%, transparent 65%),
    radial-gradient(ellipse 60% 40% at 85% 35%, rgba(41,151,255,.10)    0%, transparent 60%),
    radial-gradient(ellipse 50% 50% at 15% 70%, rgba(255,55,95,.09)     0%, transparent 60%),
    #000000;
}

/* ══════════════════════════════════════════
   BACK TO TOP BUTTON
══════════════════════════════════════════ */
#backToTop {
  position: fixed;
  bottom: 28px; right: 24px;
  z-index: 990;
  width: 44px; height: 44px;
  border-radius: 50%;
  border: 1px solid rgba(255,255,255,.12);
  background: rgba(15,15,15,.82);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  color: rgba(255,255,255,.65);
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  opacity: 0;
  transform: translateY(10px) scale(.88);
  transition:
    opacity .4s var(--ease-spring),
    transform .4s var(--ease-spring),
    background .2s, border-color .2s, color .2s;
  pointer-events: none;
  box-shadow: 0 4px 20px rgba(0,0,0,.4);
}
#backToTop.btt-visible {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}
#backToTop:hover {
  background: rgba(30,30,30,.95);
  border-color: rgba(255,255,255,.22);
  color: #fff;
  transform: translateY(-2px) scale(1);
}
#backToTop:active { transform: scale(.95); }

/* ══════════════════════════════════════════
   LAYOUT HELPERS
══════════════════════════════════════════ */
.section-container { max-width: 80rem; margin: 0 auto; padding: 0 1rem; }
@media (min-width: 768px) { .section-container { padding: 0 1.5rem; } }

.section-heading {
  text-align: center;
  margin-bottom: 3.5rem;
}

/* ══════════════════════════════════════════
   FORMS
══════════════════════════════════════════ */
.form-input {
  background: rgba(255,255,255,.04);
  border: 1px solid rgba(255,255,255,.10);
  border-radius: 10px;
  padding: .65rem 1rem;
  color: var(--text-1);
  font-size: 0.875rem;
  font-family: inherit;
  outline: none;
  width: 100%;
  transition: border-color .2s;
}
.form-input::placeholder { color: rgba(255,255,255,.3); }
.form-input:focus { border-color: rgba(123,97,255,.5); }

/* ══════════════════════════════════════════
   RESPONSIVE
══════════════════════════════════════════ */
@media (max-width: 767px) {
  .text-hero { font-size: 2.75rem !important; }
  .card-hover:hover { transform: none; }
  body { padding-bottom: 72px; }
  #backToTop { bottom: 90px; right: 14px; width: 40px; height: 40px; }
}
@media (min-width: 768px) {
  body { padding-bottom: 0; }
}