:root {
  --blue: #246BFE;
  --blue-dark: #1646B8;
  --yellow: #FFD84D;
  --red: #FF5A66;
  --ink: #14213D;
  --muted: #5F6C80;
  --bg: #F6F9FF;
  --card: #FFFFFF;
  --line: #DDE6F7;
  --shadow: 0 24px 60px rgba(36, 107, 254, 0.16);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: radial-gradient(circle at top left, #E9F1FF, transparent 32rem), var(--bg);
  line-height: 1.6;
}

a { color: inherit; }
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 1rem clamp(1rem, 5vw, 4rem);
  background: rgba(246, 249, 255, 0.86);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(221, 230, 247, 0.8);
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: .55rem;
  text-decoration: none;
  font-weight: 900;
  font-size: 1.15rem;
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: .8rem;
  background: var(--yellow);
}
nav { display: flex; gap: 1rem; color: var(--muted); font-weight: 700; font-size: .95rem; }
nav a { text-decoration: none; }
nav a:hover { color: var(--blue); }

.section { padding: clamp(3rem, 7vw, 6rem) clamp(1rem, 5vw, 4rem); max-width: 1180px; margin: 0 auto; }
.hero { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(280px, .9fr); gap: clamp(2rem, 6vw, 5rem); align-items: center; min-height: 78vh; }
.eyebrow { color: var(--blue); text-transform: uppercase; letter-spacing: .12em; font-weight: 900; font-size: .8rem; margin: 0 0 .85rem; }
h1, h2, h3 { line-height: 1.05; margin: 0; }
h1 { font-size: clamp(2.7rem, 7vw, 5.8rem); letter-spacing: -0.06em; }
h2 { font-size: clamp(2rem, 4vw, 3.4rem); letter-spacing: -0.045em; }
h3 { font-size: 1.35rem; letter-spacing: -0.02em; }
.lead { font-size: clamp(1.1rem, 2vw, 1.35rem); color: var(--muted); max-width: 42rem; }
.cta-row { display: flex; flex-wrap: wrap; align-items: center; gap: 1rem; margin: 2rem 0; }
.app-store-button {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  min-width: 170px;
  min-height: 58px;
  padding: .65rem 1.15rem;
  border-radius: 1rem;
  color: white;
  background: #05070D;
  text-decoration: none;
  box-shadow: 0 14px 30px rgba(0,0,0,.18);
}
.app-store-button .small { font-size: .75rem; opacity: .86; line-height: 1; }
.app-store-button .large { font-size: 1.35rem; font-weight: 900; line-height: 1.15; }
.secondary-link { font-weight: 900; color: var(--blue); }
.trust-list { display: flex; flex-wrap: wrap; gap: .6rem; padding: 0; margin: 0; list-style: none; }
.trust-list li { padding: .55rem .8rem; border: 1px solid var(--line); background: rgba(255,255,255,.72); border-radius: 999px; font-weight: 800; color: var(--muted); }
.hero-card { display: flex; justify-content: center; }
.phone-frame { width: min(100%, 350px); padding: .55rem; border-radius: 2.5rem; background: #111827; box-shadow: var(--shadow); transform: rotate(3deg); }
.phone-frame img { display: block; width: 100%; border-radius: 1.95rem; }
.hero-phone { position: relative; }
.hero-phone::after { content: ""; position: absolute; inset: .55rem; border-radius: 1.95rem; box-shadow: inset 0 0 0 1px rgba(255,255,255,.18); pointer-events: none; }
.section-heading { max-width: 720px; margin-bottom: 2rem; }
.section-heading p:not(.eyebrow) { color: var(--muted); font-size: 1.1rem; }
.screenshots-section { overflow: hidden; }
.screenshot-strip { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 1rem; align-items: start; }
.screenshot-strip figure { margin: 0; background: var(--card); border: 1px solid var(--line); border-radius: 1.5rem; padding: .7rem; box-shadow: 0 16px 40px rgba(20,33,61,.08); }
.screenshot-strip img { display: block; width: 100%; border-radius: 1rem; }
.screenshot-strip figcaption { padding: .75rem .25rem .25rem; text-align: center; font-weight: 900; color: var(--ink); }
.feature-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1rem; }
.feature-card, .check-card, .teacher-card, details { background: var(--card); border: 1px solid var(--line); border-radius: 1.5rem; padding: 1.4rem; box-shadow: 0 16px 40px rgba(20,33,61,.06); }
.icon { font-size: 2rem; display: inline-block; margin-bottom: 1rem; }
.feature-card p, .split-section p, details p { color: var(--muted); }
.split-section { display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; align-items: center; }
.alt { background: white; border-radius: 2rem; }
.check-card ul { margin: 0; padding: 0; list-style: none; display: grid; gap: .9rem; }
.check-card li::before { content: "✓"; color: #27C281; font-weight: 900; margin-right: .55rem; }
.quote { font-size: 1.45rem; color: var(--ink) !important; font-weight: 900; line-height: 1.2; }
.note { padding: 1rem; border-radius: 1rem; background: #FFF8D8; color: #735D00 !important; font-weight: 800; }
.final-cta { text-align: center; background: linear-gradient(135deg, var(--blue), var(--blue-dark)); color: white; border-radius: 2rem; margin-block: 3rem; box-shadow: var(--shadow); }
.final-cta p { color: rgba(255,255,255,.85); font-size: 1.2rem; }
.faq { max-width: 900px; }
details { margin-bottom: .8rem; }
summary { cursor: pointer; font-weight: 900; font-size: 1.1rem; }
.site-footer { display: flex; justify-content: space-between; gap: 1rem; flex-wrap: wrap; padding: 2rem clamp(1rem, 5vw, 4rem); color: var(--muted); border-top: 1px solid var(--line); }
.site-footer div { display: flex; gap: 1rem; }
.site-footer a { color: var(--blue); font-weight: 800; }

@media (max-width: 900px) {
  nav { display: none; }
  .hero, .split-section { grid-template-columns: 1fr; }
  .feature-grid, .screenshot-strip { grid-template-columns: 1fr 1fr; }
  .phone-frame { transform: none; }
}
@media (max-width: 560px) {
  .feature-grid { grid-template-columns: 1fr; }
  .screenshot-strip { display: flex; gap: 1rem; overflow-x: auto; scroll-snap-type: x mandatory; padding-bottom: .75rem; }
  .screenshot-strip figure { min-width: 72%; scroll-snap-align: start; }
}