/* ============================================================
   Yuzvak AI School — Design System
   Dark-navy minimalism · neon cyan → violet AI accents
   ============================================================ */

/* ---------- Tokens ---------- */
:root {
  --bg:            #060912;
  --bg-2:          #090e1c;
  --bg-3:          #0c1326;
  --surface:       rgba(255, 255, 255, 0.035);
  --surface-2:     rgba(255, 255, 255, 0.055);
  --surface-3:     rgba(255, 255, 255, 0.08);
  --border:        rgba(255, 255, 255, 0.09);
  --border-strong: rgba(255, 255, 255, 0.16);

  --text:          #eef2fb;
  --text-dim:      #9fb0cc;
  --text-faint:    #62718e;

  --cyan:          #38d3e6;
  --cyan-bright:   #5ee7f3;
  --violet:        #9a6bff;
  --violet-bright: #b18cff;
  --blue:          #4f7bff;

  --grad:          linear-gradient(118deg, #38d3e6 0%, #6f8cff 48%, #9a6bff 100%);
  --grad-soft:     linear-gradient(118deg, rgba(56,211,230,0.18), rgba(154,107,255,0.18));
  --grad-text:     linear-gradient(110deg, #7fe6f0 0%, #b6c8ff 50%, #c6a9ff 100%);

  --glow-cyan:     rgba(56, 211, 230, 0.55);
  --glow-violet:   rgba(154, 107, 255, 0.55);

  --radius-sm: 10px;
  --radius:    16px;
  --radius-lg: 24px;
  --radius-xl: 32px;

  --shadow:     0 24px 60px -24px rgba(0, 0, 0, 0.7);
  --shadow-glow: 0 0 0 1px rgba(255,255,255,0.06), 0 30px 80px -30px rgba(56,211,230,0.25);

  --maxw: 1240px;
  --gutter: clamp(20px, 5vw, 64px);

  --font-display: 'Unbounded', 'Manrope', system-ui, sans-serif;
  --font-body:    'Manrope', system-ui, -apple-system, sans-serif;

  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; scroll-padding-top: 96px; }
body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; border: none; background: none; color: inherit; }
input, textarea, select { font: inherit; color: inherit; }
ul { list-style: none; }
::selection { background: rgba(56,211,230,0.3); color: #fff; }

/* ---------- Page ambient background ---------- */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  background:
    radial-gradient(900px 600px at 78% -5%, rgba(79,123,255,0.16), transparent 60%),
    radial-gradient(700px 500px at 95% 18%, rgba(154,107,255,0.13), transparent 55%),
    radial-gradient(800px 600px at 0% 100%, rgba(56,211,230,0.08), transparent 60%),
    var(--bg);
}
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(to right, rgba(255,255,255,0.025) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(255,255,255,0.025) 1px, transparent 1px);
  background-size: 72px 72px;
  -webkit-mask-image: radial-gradient(1100px 700px at 70% 0%, #000 0%, transparent 75%);
          mask-image: radial-gradient(1100px 700px at 70% 0%, #000 0%, transparent 75%);
  pointer-events: none;
}

/* ---------- Layout ---------- */
.wrap { width: 100%; max-width: var(--maxw); margin-inline: auto; padding-inline: var(--gutter); }
.section { padding-block: clamp(64px, 9vw, 130px); position: relative; }
.section--tight { padding-block: clamp(48px, 6vw, 80px); }

/* ---------- Type ---------- */
h1, h2, h3, h4 { font-weight: 700; line-height: 1.08; letter-spacing: -0.02em; }
.display {
  font-family: var(--font-display);
  font-weight: 800;
  text-transform: uppercase;
  line-height: 0.98;
  letter-spacing: -0.01em;
}
.h-hero { font-size: clamp(2.3rem, 5vw, 4.4rem); }
.h2 { font-size: clamp(1.85rem, 3.6vw, 3.1rem); font-family: var(--font-display); font-weight: 700; text-transform: uppercase; letter-spacing: -0.01em; }
.h3 { font-size: clamp(1.2rem, 1.8vw, 1.5rem); font-weight: 700; }
.lead { font-size: clamp(1.05rem, 1.5vw, 1.25rem); color: var(--text-dim); line-height: 1.65; text-wrap: pretty; }
.muted { color: var(--text-dim); }
.faint { color: var(--text-faint); }

.grad-text {
  background: var(--grad-text);
  -webkit-background-clip: text;
          background-clip: text;
  color: transparent;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.22em;
  color: var(--cyan-bright);
}
.eyebrow::before {
  content: "";
  width: 26px; height: 1px;
  background: linear-gradient(90deg, var(--cyan), transparent);
}
.eyebrow--center::before { display: none; }

.section-head { max-width: 720px; }
.section-head .h2 { margin-top: 18px; }
.section-head .lead { margin-top: 18px; }
.section-head--center { margin-inline: auto; text-align: center; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  padding: 16px 30px;
  border-radius: 100px;
  font-weight: 700;
  font-size: 0.98rem;
  letter-spacing: 0.01em;
  transition: transform .25s var(--ease), box-shadow .25s var(--ease), background .25s var(--ease);
  white-space: nowrap;
}
.btn--primary {
  background: var(--grad);
  color: #04121a;
  box-shadow: 0 10px 30px -8px var(--glow-cyan), 0 0 0 1px rgba(255,255,255,0.08) inset;
}
.btn--primary:hover { transform: translateY(-2px); box-shadow: 0 16px 40px -8px var(--glow-violet), 0 0 0 1px rgba(255,255,255,0.12) inset; }
.btn--ghost {
  background: var(--surface-2);
  color: var(--text);
  border: 1px solid var(--border-strong);
  -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px);
}
.btn--ghost:hover { background: var(--surface-3); transform: translateY(-2px); }
.btn--lg { padding: 19px 38px; font-size: 1.05rem; }
.btn--block { width: 100%; }
.btn .arrow { transition: transform .25s var(--ease); }
.btn:hover .arrow { transform: translateX(4px); }

.link-arrow {
  display: inline-flex; align-items: center; gap: 8px;
  color: var(--text-dim); font-weight: 600;
  border-bottom: 1px solid transparent;
  transition: color .2s, border-color .2s;
}
.link-arrow:hover { color: var(--cyan-bright); border-color: rgba(94,231,243,0.4); }

/* ---------- Cards ---------- */
.card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 30px;
  -webkit-backdrop-filter: blur(10px); backdrop-filter: blur(10px);
  transition: transform .35s var(--ease), border-color .35s var(--ease), background .35s var(--ease);
}
.card:hover { transform: translateY(-5px); border-color: var(--border-strong); background: var(--surface-2); }
.card__icon {
  width: 52px; height: 52px; border-radius: 14px;
  display: grid; place-items: center;
  background: var(--grad-soft);
  border: 1px solid var(--border);
  color: var(--cyan-bright);
  margin-bottom: 22px;
}
.card__icon svg { width: 26px; height: 26px; }
.card h3 { margin-bottom: 10px; }
.card p { color: var(--text-dim); font-size: 1rem; }

.pill {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 8px 16px; border-radius: 100px;
  background: var(--surface-2); border: 1px solid var(--border);
  font-size: 0.85rem; color: var(--text-dim); font-weight: 600;
}

/* ---------- Icon line style ---------- */
.ic { stroke: currentColor; stroke-width: 1.6; fill: none; stroke-linecap: round; stroke-linejoin: round; }

/* ---------- Header ---------- */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  transition: background .3s, border-color .3s, backdrop-filter .3s;
  border-bottom: 1px solid transparent;
}
.site-header.scrolled {
  background: rgba(8, 12, 24, 0.72);
  -webkit-backdrop-filter: blur(16px) saturate(140%); backdrop-filter: blur(16px) saturate(140%);
  border-bottom-color: var(--border);
}
.nav { display: flex; align-items: center; justify-content: space-between; height: 76px; gap: 24px; }
.brand { display: flex; align-items: center; gap: 13px; flex-shrink: 0; }
.brand__mark {
  width: 44px; height: 44px; border-radius: 12px;
  display: grid; place-items: center;
  background: var(--grad);
  color: #04121a; font-family: var(--font-display); font-weight: 800; font-size: 1.15rem;
  box-shadow: 0 8px 24px -8px var(--glow-cyan);
}
.brand__name { display: flex; flex-direction: column; line-height: 1.05; }
.brand__name b { font-family: var(--font-display); font-weight: 700; font-size: 0.95rem; letter-spacing: 0.02em; }
.brand__name span { font-size: 0.68rem; letter-spacing: 0.26em; text-transform: uppercase; color: var(--text-faint); }
.nav__links { display: flex; align-items: center; gap: 6px; }
.nav__links a {
  padding: 9px 15px; border-radius: 10px; font-size: 0.95rem; font-weight: 600; color: var(--text-dim);
  white-space: nowrap;
  transition: color .2s, background .2s;
}
.nav__links a:hover, .nav__links a.active { color: var(--text); background: var(--surface-2); }
.nav__actions { display: flex; align-items: center; gap: 14px; flex-shrink: 0; }
.nav__login { font-weight: 600; color: var(--text-dim); transition: color .2s; }
.nav__login:hover { color: var(--text); }
.nav__toggle { display: none; width: 44px; height: 44px; border-radius: 10px; border: 1px solid var(--border); place-items: center; }
.nav__toggle svg { width: 22px; height: 22px; color: var(--text); }

/* mobile menu */
.mobile-menu {
  position: fixed; inset: 0; z-index: 99;
  background: rgba(6,9,18,0.96);
  -webkit-backdrop-filter: blur(20px); backdrop-filter: blur(20px);
  display: flex; flex-direction: column; justify-content: center; gap: 6px;
  padding: var(--gutter);
  transform: translateY(-100%); opacity: 0; pointer-events: none;
  transition: transform .4s var(--ease), opacity .4s var(--ease);
}
.mobile-menu.open { transform: translateY(0); opacity: 1; pointer-events: auto; }
.mobile-menu a { font-family: var(--font-display); text-transform: uppercase; font-size: 1.6rem; font-weight: 700; padding: 12px 0; color: var(--text); border-bottom: 1px solid var(--border); }
.mobile-menu a:last-of-type { border: none; }
.mobile-menu .btn { margin-top: 24px; }

/* ---------- Footer ---------- */
.site-footer { border-top: 1px solid var(--border); background: var(--bg-2); padding-block: clamp(56px, 6vw, 88px) 36px; }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1.2fr; gap: 40px; }
.footer-col h4 { font-size: 0.82rem; text-transform: uppercase; letter-spacing: 0.16em; color: var(--text-faint); margin-bottom: 18px; font-weight: 700; }
.footer-col ul { display: flex; flex-direction: column; gap: 11px; }
.footer-col a, .footer-col li { color: var(--text-dim); font-size: 0.95rem; transition: color .2s; }
.footer-col a:hover { color: var(--cyan-bright); }
.footer-about p { color: var(--text-dim); font-size: 0.95rem; margin-top: 18px; max-width: 340px; }
.footer-legalrow { color: var(--text-faint); font-size: 0.85rem; line-height: 1.7; }
.footer-bottom { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 16px; margin-top: 52px; padding-top: 28px; border-top: 1px solid var(--border); color: var(--text-faint); font-size: 0.85rem; }
.footer-bottom .dots { display: flex; gap: 18px; flex-wrap: wrap; }

/* ---------- Reveal on scroll ---------- */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity .7s var(--ease), transform .7s var(--ease); }
.reveal.in { opacity: 1; transform: none; }
.reveal[data-d="1"] { transition-delay: .08s; }
.reveal[data-d="2"] { transition-delay: .16s; }
.reveal[data-d="3"] { transition-delay: .24s; }
.reveal[data-d="4"] { transition-delay: .32s; }

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
  .reveal { opacity: 1; transform: none; }
  html { scroll-behavior: auto; }
}

/* ---------- Responsive ---------- */
@media (max-width: 940px) {
  .nav__links, .nav__login { display: none; }
  .nav__toggle { display: grid; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .footer-about { grid-column: 1 / -1; }
}
@media (max-width: 560px) {
  body { font-size: 16px; }
  .footer-grid { grid-template-columns: 1fr; }
  .btn { width: 100%; }
  .nav__actions .btn { display: none; }
}