:root {
  --sky-top: #4cc9f0;
  --sky-bottom: #bde0fe;
  --primary: #ef476f;
  --primary-dark: #d63d5f;
  --accent: #ffd166;
  --ink: #073b4c;
  --text: #2b3a4a;
  --muted: #5f7285;
  --bg: #ffffff;
  --bg-alt: #f3f9ff;
  --radius: 18px;
  --shadow: 0 10px 30px rgba(7, 59, 76, 0.12);
  --nav-h: 64px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; scroll-padding-top: var(--nav-h); }

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; }

.container { width: min(1120px, 100% - 32px); margin-inline: auto; }
.container--narrow { width: min(760px, 100% - 32px); }

/* Buttons */
.btn {
  display: inline-block;
  padding: 14px 32px;
  border-radius: 999px;
  background: var(--primary);
  color: #fff;
  font-weight: 700;
  box-shadow: 0 6px 0 var(--primary-dark);
  transition: transform .15s, box-shadow .15s, background .2s;
}
.btn:hover { transform: translateY(-2px); box-shadow: 0 8px 0 var(--primary-dark); }
.btn:active { transform: translateY(4px); box-shadow: 0 2px 0 var(--primary-dark); }
.btn--small { padding: 8px 20px; box-shadow: 0 4px 0 var(--primary-dark); }
.btn--ghost { background: rgba(255,255,255,.85); color: var(--ink); box-shadow: 0 6px 0 rgba(7,59,76,.2); }
.btn--ghost:hover { box-shadow: 0 8px 0 rgba(7,59,76,.2); }
.btn--light { background: #fff; color: var(--primary); box-shadow: 0 6px 0 rgba(0,0,0,.15); font-size: 1.15rem; }
.btn--light:hover { box-shadow: 0 8px 0 rgba(0,0,0,.15); }

/* Nav */
.nav {
  position: fixed; inset: 0 0 auto 0; z-index: 50;
  height: var(--nav-h);
  transition: background .3s, box-shadow .3s;
}
.nav.is-scrolled { background: rgba(255,255,255,.92); backdrop-filter: blur(8px); box-shadow: 0 2px 16px rgba(7,59,76,.08); }
.nav__inner { height: 100%; display: flex; align-items: center; justify-content: space-between; }
.nav__brand { display: flex; align-items: center; gap: 10px; font-weight: 800; font-size: 1.2rem; color: var(--ink); }
.nav__links { display: flex; align-items: center; gap: 28px; font-weight: 600; color: var(--ink); }
.nav__links a:not(.btn):hover { color: var(--primary); }
.nav__toggle { display: none; background: none; border: 0; cursor: pointer; padding: 8px; }
.nav__toggle span { display: block; width: 24px; height: 3px; margin: 4px 0; border-radius: 2px; background: var(--ink); transition: transform .3s, opacity .3s; }

/* Hero */
.hero {
  position: relative; overflow: hidden;
  min-height: 100vh; min-height: 100svh;
  display: flex; align-items: center;
  padding: calc(var(--nav-h) + 24px) 0 48px;
  background: linear-gradient(180deg, var(--sky-top), var(--sky-bottom));
}
.hero__sky { position: absolute; inset: 0; width: 100%; height: 100%; }
.hero__inner { position: relative; display: grid; grid-template-columns: 1.1fr 1fr; align-items: center; gap: 32px; }
.hero__tag {
  display: inline-block; padding: 4px 14px; margin-bottom: 16px;
  border-radius: 999px; background: rgba(255,255,255,.7);
  color: var(--ink); font-weight: 600; font-size: .9rem;
}
.hero h1 { font-size: clamp(2.2rem, 5vw, 3.6rem); line-height: 1.2; color: var(--ink); font-weight: 900; }
.highlight { color: var(--primary); }
.hero__desc { margin: 20px 0 32px; font-size: 1.1rem; color: var(--ink); opacity: .85; }
.hero__actions { display: flex; flex-wrap: wrap; gap: 16px; }
.hero__art { position: relative; }
.plane { width: 100%; max-width: 440px; margin-inline: auto; animation: float 3s ease-in-out infinite; filter: drop-shadow(0 20px 20px rgba(7,59,76,.2)); }
.propeller { transform-origin: 213px 82px; animation: spin .15s linear infinite; }

@keyframes float {
  0%, 100% { transform: translateY(0) rotate(-3deg); }
  50% { transform: translateY(-18px) rotate(2deg); }
}
@keyframes spin {
  from { transform: scaleY(1); }
  50% { transform: scaleY(.1); }
  to { transform: scaleY(1); }
}

/* Sections */
.section { padding: 96px 0; }
.section--alt { background: var(--bg-alt); }
.section__title { text-align: center; font-size: clamp(1.8rem, 3.5vw, 2.4rem); color: var(--ink); font-weight: 900; }
.section__sub { text-align: center; color: var(--muted); margin: 8px 0 48px; }

.grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.card {
  padding: 32px 24px; border-radius: var(--radius);
  background: #fff; box-shadow: var(--shadow); text-align: center;
  transition: transform .25s;
}
.card:hover { transform: translateY(-6px); }
.card__icon {
  width: 72px; height: 72px; margin: 0 auto 16px;
  display: grid; place-items: center; font-size: 2rem;
  border-radius: 50%; background: var(--bg-alt);
}
.card h3 { color: var(--ink); margin-bottom: 8px; }
.card p { color: var(--muted); font-size: .95rem; }

.steps { list-style: none; display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; counter-reset: step; }
.step { position: relative; padding: 40px 28px 28px; border-radius: var(--radius); background: #fff; box-shadow: var(--shadow); }
.step__num {
  position: absolute; top: -22px; left: 28px;
  width: 44px; height: 44px; display: grid; place-items: center;
  border-radius: 50%; background: var(--accent); color: var(--ink);
  font-weight: 900; font-size: 1.2rem; box-shadow: 0 4px 0 #e0b04a;
}
.step h3 { color: var(--ink); margin-bottom: 6px; }
.step p { color: var(--muted); }

.faq { border-radius: 14px; background: var(--bg-alt); margin-bottom: 14px; overflow: hidden; }
.faq summary {
  cursor: pointer; list-style: none; padding: 18px 24px;
  font-weight: 700; color: var(--ink);
  display: flex; justify-content: space-between; align-items: center;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font-size: 1.4rem; color: var(--primary); transition: transform .2s; }
.faq[open] summary::after { transform: rotate(45deg); }
.faq p { padding: 0 24px 18px; color: var(--muted); }

/* CTA */
.cta { padding: 96px 0; background: linear-gradient(135deg, var(--primary), #ff8fa3); color: #fff; text-align: center; }
.cta h2 { font-size: clamp(1.8rem, 4vw, 2.6rem); font-weight: 900; }
.cta p { margin: 8px 0 32px; opacity: .9; }

/* Footer */
.footer { padding: 28px 0; background: var(--ink); color: rgba(255,255,255,.7); font-size: .9rem; }
.footer__inner { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.footer a:hover { color: #fff; }

/* Toast */
.toast {
  position: fixed; left: 50%; bottom: 32px; z-index: 100;
  transform: translate(-50%, 20px); opacity: 0; pointer-events: none;
  padding: 12px 24px; border-radius: 999px;
  background: var(--ink); color: #fff; font-weight: 600;
  transition: opacity .3s, transform .3s;
}
.toast.is-visible { opacity: 1; transform: translate(-50%, 0); }

/* Reveal on scroll */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .6s, transform .6s; }
.reveal.is-visible { opacity: 1; transform: none; }

/* Responsive */
@media (max-width: 960px) {
  .grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 760px) {
  .nav { background: rgba(255,255,255,.92); backdrop-filter: blur(8px); }
  .nav__toggle { display: block; }
  .nav__links {
    position: absolute; top: var(--nav-h); left: 0; right: 0;
    flex-direction: column; gap: 0; padding: 8px 16px 20px;
    background: #fff; box-shadow: 0 12px 24px rgba(7,59,76,.1);
    transform: translateY(-8px); opacity: 0; visibility: hidden;
    transition: opacity .25s, transform .25s, visibility .25s;
  }
  .nav__links a:not(.btn) { width: 100%; padding: 14px 0; text-align: center; border-bottom: 1px solid var(--bg-alt); }
  .nav__links .btn { margin-top: 16px; }
  .nav.is-open .nav__links { transform: none; opacity: 1; visibility: visible; }
  .nav.is-open .nav__toggle span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .nav.is-open .nav__toggle span:nth-child(2) { opacity: 0; }
  .nav.is-open .nav__toggle span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

  .hero__inner { grid-template-columns: 1fr; text-align: center; }
  .hero__art { order: -1; }
  .plane { max-width: 280px; }
  .hero__actions { justify-content: center; }
  .hero__desc br { display: none; }

  .section, .cta { padding: 72px 0; }
  .grid, .steps { grid-template-columns: 1fr; }
  .steps { gap: 40px; }
  .footer__inner { justify-content: center; text-align: center; }
}

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