/* ============================================
   N V Education — Design tokens
   ============================================ */
:root {
  --navy: #0f2647;
  --blue-deep: #14509e;
  --blue: #2872c9;
  --blue-soft: #eaf1fb;
  --sky: #4fc3e0;
  --leaf: #3aa66b;
  --paper: #fbfcfe;
  --ink: #16233a;
  --ink-soft: #52627c;
  --line: #dde6f2;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 10px 30px -14px rgba(15, 38, 71, 0.25);
  --maxw: 1120px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.55;
}

h1, h2, h3, h4 {
  font-family: "Sora", "Inter", sans-serif;
  color: var(--navy);
  margin: 0;
  line-height: 1.15;
}

p { margin: 0; }
a { text-decoration: none; color: inherit; }
img { max-width: 100%; display: block; }
ul { margin: 0; padding: 0; list-style: none; }

.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: "Sora", sans-serif;
  font-size: 15px;
  font-weight: 600;
  padding: 13px 24px;
  border-radius: 999px;
  border: none;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn:focus-visible { outline: 3px solid var(--sky); outline-offset: 2px; }

.btn-primary {
  background: var(--paper);
  color: var(--blue-deep);
  box-shadow: 0 6px 18px -6px rgba(0,0,0,0.25);
}
.btn-ghost {
  background: transparent;
  color: var(--paper);
  border: 1.5px solid rgba(251, 252, 254, 0.55);
}
.btn-solid {
  background: var(--blue-deep);
  color: var(--paper);
}
.btn-solid:hover { box-shadow: 0 10px 22px -8px rgba(20, 80, 158, 0.55); }

/* ============================================
   Header / Nav
   ============================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(251, 252, 254, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
}
.brand img { width: 38px; height: 38px; }
.brand-name {
  font-family: "Sora", sans-serif;
  font-weight: 700;
  font-size: 17px;
  color: var(--navy);
}
.brand-tag {
  display: block;
  font-family: "Inter", sans-serif;
  font-weight: 400;
  font-size: 11px;
  color: var(--ink-soft);
  margin-top: 1px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
}
.nav-links a {
  font-size: 14.5px;
  font-weight: 500;
  color: var(--ink-soft);
  padding: 6px 2px;
  border-bottom: 2px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--blue-deep);
  border-color: var(--blue-deep);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--navy);
  margin: 5px 0;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

/* ============================================
   Hero
   ============================================ */
.hero {
  background: linear-gradient(160deg, var(--navy) 0%, var(--blue-deep) 62%, var(--blue) 100%);
  padding: 64px 0 96px;
}
.hero .wrap {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 40px;
  align-items: center;
}
.hero-eyebrow {
  color: var(--sky);
  font-weight: 600;
  font-size: 14px;
  margin-bottom: 14px;
}
.hero h1 {
  color: var(--paper);
  font-size: clamp(32px, 4.2vw, 46px);
  font-weight: 700;
  max-width: 11ch;
}
.hero p.lead {
  color: rgba(251, 252, 254, 0.8);
  font-size: 17px;
  margin-top: 18px;
  max-width: 46ch;
}
.hero-actions {
  display: flex;
  gap: 14px;
  margin-top: 30px;
  flex-wrap: wrap;
}

.hero-art {
  position: relative;
  background: rgba(251, 252, 254, 0.08);
  border: 1px solid rgba(251, 252, 254, 0.18);
  border-radius: var(--radius);
  padding: 28px;
}
.hero-art img { width: 100%; max-width: 240px; margin: 0 auto; }

/* Stats strip, overlapping hero */
.stats {
  max-width: var(--maxw);
  margin: -52px auto 0;
  padding: 0 24px;
}
.stats-card {
  background: var(--paper);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  padding: 26px 20px;
}
.stat { text-align: center; padding: 0 12px; }
.stat + .stat { border-left: 1px solid var(--line); }
.stat b {
  display: block;
  font-family: "Sora", sans-serif;
  font-size: 26px;
  color: var(--navy);
}
.stat span {
  font-size: 13px;
  color: var(--ink-soft);
}

/* ============================================
   Section shell
   ============================================ */
section.block { padding: 72px 0; }
.block-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 28px;
  gap: 16px;
}
.block-head h2 { font-size: 26px; }
.block-head p { color: var(--ink-soft); font-size: 14.5px; margin-top: 6px; }
.see-all {
  font-size: 14px;
  font-weight: 600;
  color: var(--blue-deep);
  white-space: nowrap;
}

/* ============================================
   Subjects
   ============================================ */
.subjects-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
}
.subject-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 16px;
  text-align: center;
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.subject-card:hover { border-color: var(--blue); transform: translateY(-2px); }
.subject-icon {
  width: 48px; height: 48px;
  margin: 0 auto 12px;
  border-radius: 12px;
  background: var(--blue-soft);
  display: flex; align-items: center; justify-content: center;
  font-size: 20px;
}
.subject-card b { display: block; font-size: 14px; font-weight: 600; color: var(--ink); }
.subject-card span { font-size: 12px; color: var(--ink-soft); }
.subject-card.more {
  background: var(--blue-soft);
  border-style: dashed;
  border-color: var(--blue);
  color: var(--blue-deep);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

/* ============================================
   Videos
   ============================================ */
.videos-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}
.video-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}
.video-thumb {
  aspect-ratio: 16/9;
  background: var(--blue-soft);
  display: flex; align-items: center; justify-content: center;
  position: relative;
}
.video-thumb .play {
  width: 44px; height: 44px;
  background: var(--paper);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 6px 16px -4px rgba(15,38,71,0.3);
  color: var(--blue-deep);
  font-size: 16px;
}
.video-meta { padding: 14px 16px; }
.video-meta b { display: block; font-size: 14.5px; margin-bottom: 4px; }
.video-meta span { font-size: 12.5px; color: var(--ink-soft); }

/* ============================================
   Quiz banner
   ============================================ */
.quiz-banner {
  background: var(--blue-soft);
  border-radius: var(--radius);
  padding: 32px;
  display: flex;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
}
.quiz-icon {
  width: 56px; height: 56px;
  border-radius: 14px;
  background: var(--paper);
  display: flex; align-items: center; justify-content: center;
  font-size: 24px;
  flex-shrink: 0;
}
.quiz-text { flex: 1; min-width: 220px; }
.quiz-text b { display: block; font-family: "Sora", sans-serif; font-size: 17px; color: var(--navy); margin-bottom: 3px; }
.quiz-text span { font-size: 14px; color: var(--ink-soft); }

/* ============================================
   About
   ============================================ */
.about {
  background: var(--navy);
}
.about .wrap {
  display: grid;
  grid-template-columns: 0.85fr 1.15fr;
  gap: 48px;
  align-items: center;
}
.about-badge {
  width: 88px; height: 88px;
  border-radius: 20px;
  background: rgba(251,252,254,0.08);
  border: 1px solid rgba(251,252,254,0.18);
  display: flex; align-items: center; justify-content: center;
}
.about-badge img { width: 56px; }
.about h2 { color: var(--paper); font-size: 24px; margin-bottom: 14px; }
.about p { color: rgba(251,252,254,0.75); font-size: 15px; }

/* ============================================
   Footer
   ============================================ */
.site-footer {
  background: var(--navy);
  border-top: 1px solid rgba(251,252,254,0.12);
  padding: 40px 0 28px;
}
.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 24px;
  flex-wrap: wrap;
  padding-bottom: 28px;
}
.footer-brand { display: flex; align-items: center; gap: 10px; }
.footer-brand img { width: 32px; height: 32px; }
.footer-brand b { color: var(--paper); font-family: "Sora", sans-serif; font-size: 15px; }
.footer-links { display: flex; gap: 28px; flex-wrap: wrap; }
.footer-links a { color: rgba(251,252,254,0.75); font-size: 14px; }
.footer-links a:hover { color: var(--sky); }
.footer-bottom {
  border-top: 1px solid rgba(251,252,254,0.12);
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
  font-size: 12.5px;
  color: rgba(251,252,254,0.55);
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 860px) {
  .hero .wrap { grid-template-columns: 1fr; }
  .hero-art { order: -1; max-width: 220px; margin: 0 auto; }
  .about .wrap { grid-template-columns: 1fr; text-align: center; }
  .about-badge { margin: 0 auto; }
  .videos-row { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
  .nav-links {
    position: absolute;
    top: 100%; left: 0; right: 0;
    background: var(--paper);
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
    padding: 12px 24px 20px;
    border-bottom: 1px solid var(--line);
    display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { width: 100%; padding: 10px 0; }
  .nav-toggle { display: block; }

  .stats-card { grid-template-columns: 1fr; gap: 14px; }
  .stat { border-left: none !important; padding: 0; }
  .stat + .stat { border-top: 1px solid var(--line); padding-top: 14px; }

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

  section.block { padding: 52px 0; }
  .block-head { flex-direction: column; align-items: flex-start; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; scroll-behavior: auto !important; }
}

/* ============================================
   Inner page hero (About / Videos / Tests / Contact)
   ============================================ */
.page-hero {
  background: linear-gradient(160deg, var(--navy) 0%, var(--blue-deep) 70%);
  padding: 52px 0 44px;
}
.page-hero .lead { color: rgba(251,252,254,0.78); max-width: 50ch; }

/* ============================================
   Videos page: filter chips + grid
   ============================================ */
.filter-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 32px;
}
.chip {
  font-family: "Inter", sans-serif;
  font-size: 13.5px;
  font-weight: 500;
  padding: 9px 16px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink-soft);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}
.chip:hover { border-color: var(--blue); }
.chip.active {
  background: var(--blue-deep);
  border-color: var(--blue-deep);
  color: var(--paper);
}

.videos-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}
.empty-msg {
  text-align: center;
  color: var(--ink-soft);
  font-size: 14.5px;
  padding: 40px 0;
}

/* ============================================
   Tests / Quiz
   ============================================ */
.quiz-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 14px;
}
.quiz-subject-label {
  font-family: "Sora", sans-serif;
  font-weight: 600;
  color: var(--navy);
  font-size: 15px;
}
.quiz-progress {
  font-size: 13px;
  color: var(--ink-soft);
}
.quiz-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
  margin-bottom: 20px;
}
.quiz-card h3 { font-size: 19px; margin-bottom: 20px; }
.quiz-options { display: grid; gap: 10px; }
.quiz-option {
  text-align: left;
  padding: 13px 16px;
  border-radius: var(--radius-sm);
  border: 1.5px solid var(--line);
  background: var(--paper);
  font-family: "Inter", sans-serif;
  font-size: 14.5px;
  color: var(--ink);
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.quiz-option:hover { border-color: var(--blue); }
.quiz-option.selected { border-color: var(--blue-deep); background: var(--blue-soft); }
.quiz-option.correct { border-color: var(--leaf); background: #e9f7ef; }
.quiz-option.incorrect { border-color: #d64545; background: #fbeaea; }
.quiz-option:disabled { cursor: default; }

.quiz-result { text-align: center; max-width: 440px; margin: 0 auto; padding: 20px 0 40px; }
.quiz-score-badge {
  width: 88px; height: 88px;
  margin: 0 auto 18px;
  border-radius: 50%;
  background: var(--blue-soft);
  color: var(--blue-deep);
  font-family: "Sora", sans-serif;
  font-weight: 700;
  font-size: 20px;
  display: flex; align-items: center; justify-content: center;
}

/* ============================================
   Contact page
   ============================================ */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}
.contact-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.contact-card:hover { border-color: var(--blue); transform: translateY(-2px); }
.contact-card .subject-icon { width: 52px; height: 52px; font-size: 22px; margin-bottom: 14px; }
.contact-card b { display: block; font-size: 15px; margin-bottom: 4px; }
.contact-card span { font-size: 13px; color: var(--ink-soft); word-break: break-word; }

@media (max-width: 640px) {
  .videos-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
}