:root {
  --sky: #46c8ed;
  --sky-dark: #109fcf;
  --sky-soft: #eaf9ff;
  --green: #40bd70;
  --green-dark: #188f51;
  --green-soft: #effbf3;
  --yellow: #ffc94f;
  --yellow-soft: #fff7d9;
  --orange: #ff9f38;
  --ink: #173d43;
  --muted: #607b7e;
  --line: #dceeee;
  --white: #fff;
  --shadow: 0 18px 50px rgba(24, 101, 108, .10);
  --shadow-soft: 0 10px 30px rgba(24, 101, 108, .08);
  --radius-lg: 32px;
  --radius-md: 22px;
  --header-height: 76px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--header-height) + 18px); }
body {
  margin: 0;
  color: var(--ink);
  background: var(--white);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; height: auto; }
button, a { -webkit-tap-highlight-color: transparent; }
.section-shell { width: min(1200px, calc(100% - 48px)); margin-inline: auto; }
.skip-link { position: fixed; z-index: 200; left: 12px; top: -80px; padding: 10px 16px; border-radius: 8px; background: var(--ink); color: white; transition: top .2s; }
.skip-link:focus { top: 10px; }

.site-header { position: fixed; z-index: 100; inset: 0 0 auto; height: var(--header-height); background: rgba(255,255,255,.88); border-bottom: 1px solid rgba(220,238,238,.75); backdrop-filter: blur(18px); -webkit-backdrop-filter: blur(18px); }
.nav-wrap { width: min(1200px, calc(100% - 48px)); height: 100%; margin: auto; display: flex; align-items: center; justify-content: space-between; }
.brand { display: inline-flex; align-items: center; gap: 11px; font-weight: 800; letter-spacing: -.02em; white-space: nowrap; }
.brand-logo { width: 44px; height: 44px; border-radius: 14px; object-fit: cover; }
.brand-mark { display: grid; place-items: center; width: 40px; height: 40px; border-radius: 13px 13px 18px; color: white; background: var(--green); box-shadow: inset -4px -4px 0 rgba(0,0,0,.06); font: 900 22px/1 Georgia, serif; transform: rotate(-3deg); }
.site-nav { display: flex; align-items: center; gap: 10px; }
.site-nav a { padding: 9px 13px; border-radius: 999px; font-size: 15px; font-weight: 600; color: #3f5c60; transition: color .2s, background .2s, transform .2s; }
.site-nav a:hover, .site-nav a:focus-visible { color: var(--green-dark); background: var(--green-soft); }
.site-nav .nav-cta { padding-inline: 20px; margin-left: 6px; }
.site-nav a.is-active { color: white; background: var(--green); box-shadow: 0 8px 20px rgba(64,189,112,.22); }
.site-nav a.is-active:hover, .site-nav a.is-active:focus-visible { color: white; background: var(--green-dark); transform: translateY(-2px); }
.nav-toggle { display: none; width: 44px; height: 44px; border: 0; border-radius: 14px; background: var(--green-soft); padding: 11px; cursor: pointer; }
.nav-toggle span { display: block; width: 100%; height: 2px; margin: 5px 0; border-radius: 2px; background: var(--ink); transition: transform .2s, opacity .2s; }

.hero { position: relative; min-height: 760px; padding: calc(var(--header-height) + 88px) 0 118px; overflow: hidden; background: linear-gradient(180deg, #f3fcff 0%, #fbfffd 70%, #fff 100%); }
.hero-inner { position: relative; z-index: 2; display: grid; grid-template-columns: minmax(380px, .82fr) minmax(520px, 1.18fr); gap: 58px; align-items: center; }
.eyebrow { margin: 0 0 14px; color: var(--green-dark); font-size: 14px; font-weight: 800; letter-spacing: .08em; }
.hero h1 { margin: 0; font-size: clamp(48px, 5vw, 76px); line-height: 1.08; letter-spacing: -.06em; color: #153f46; }
.hero-slogan { margin: 18px 0 12px; color: var(--orange); font-size: clamp(23px, 2.4vw, 32px); font-weight: 800; letter-spacing: -.02em; }
.hero-description { max-width: 560px; margin: 0; color: var(--muted); font-size: 17px; line-height: 1.85; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 34px; }
.button { display: inline-flex; align-items: center; justify-content: center; min-width: 126px; padding: 13px 24px; border: 1px solid transparent; border-radius: 999px; font-weight: 800; transition: transform .2s, box-shadow .2s, background .2s; }
.button:hover, .button:focus-visible { transform: translateY(-3px); }
.button-primary { color: white; background: var(--green); box-shadow: 0 12px 24px rgba(64,189,112,.25); }
.button-primary:hover { background: var(--green-dark); box-shadow: 0 14px 30px rgba(24,143,81,.28); }
.button-primary span { margin-left: 9px; font-size: 20px; }
.button-secondary { border-color: var(--line); background: white; box-shadow: var(--shadow-soft); }
.button-secondary:hover { border-color: #b9e3cd; color: var(--green-dark); }
.hero-visual { position: relative; padding: 25px 8px; }
.screenshot-window { overflow: hidden; border: 8px solid white; border-radius: var(--radius-lg); background: #dff7ff; box-shadow: 0 30px 80px rgba(20,126,151,.18); }
.window-bar { height: 34px; display: flex; align-items: center; gap: 6px; padding: 0 12px; background: white; color: #7b9699; font-size: 10px; }
.window-bar i { width: 7px; height: 7px; border-radius: 50%; background: #ffcd62; }
.window-bar i:first-child { background: #ff8c78; }
.window-bar i:nth-child(2) { background: #ffc954; }
.window-bar i:nth-child(3) { background: #50c986; }
.window-bar span { margin-inline: auto; transform: translateX(-16px); }
.hero-window { transform: rotate(1.3deg); }
.hero-window img { width: 100%; aspect-ratio: 2048 / 941; object-fit: contain; background: #6bd6ef; }
.visual-badge { position: absolute; display: inline-flex; align-items: center; gap: 8px; padding: 10px 15px; border: 4px solid white; border-radius: 17px; background: rgba(255,255,255,.96); box-shadow: var(--shadow); color: #365f62; font-size: 13px; font-weight: 800; }
.visual-badge b { display: grid; place-items: center; width: 29px; height: 29px; border-radius: 10px; color: white; background: var(--sky); }
.badge-read { left: -14px; bottom: -6px; }
.badge-level { right: -10px; top: 2px; }
.badge-level b { background: var(--yellow); color: #845b00; font-size: 11px; }
.hero-decor { position: absolute; }
.cloud { width: 180px; height: 44px; border-radius: 999px; background: rgba(255,255,255,.82); box-shadow: 52px -20px 0 -4px rgba(255,255,255,.82), 105px 2px 0 -12px rgba(255,255,255,.82); }
.cloud-a { top: 120px; left: -60px; }
.cloud-b { right: 5%; bottom: 82px; transform: scale(.7); opacity: .7; }
.leaf { width: 120px; height: 65px; border: 16px solid rgba(64,189,112,.07); border-left: 0; border-bottom: 0; border-radius: 0 100% 0 100%; transform: rotate(28deg); }
.leaf-a { left: 42%; top: 100px; }
.hero-wave { position: absolute; right: -4%; bottom: -100px; width: 48%; height: 190px; border-radius: 50% 50% 0 0; background: rgba(64,189,112,.06); transform: rotate(-5deg); }

.section { padding: 102px 0; }
.section-heading { max-width: 670px; margin: 0 auto 50px; text-align: center; }
.section-heading h2, .intro-copy h2, .download h2 { margin: 0 0 14px; font-size: clamp(32px, 3.6vw, 48px); line-height: 1.24; letter-spacing: -.045em; }
.section-heading > p:last-child, .intro-copy > p:last-child, .download-copy > p:last-child { margin: 0; color: var(--muted); font-size: 16px; }
.feature-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.feature-card { min-height: 250px; padding: 30px 26px; border: 1px solid #e6f2ef; border-radius: var(--radius-md); background: white; box-shadow: var(--shadow-soft); transition: transform .25s, box-shadow .25s; }
.feature-card:hover { transform: translateY(-7px); box-shadow: 0 18px 38px rgba(24,101,108,.13); }
.feature-icon { display: grid; place-items: center; width: 60px; height: 60px; margin-bottom: 25px; border-radius: 19px; color: var(--green-dark); background: var(--green-soft); font-weight: 900; box-shadow: inset 0 -4px 0 rgba(64,189,112,.08); }
.feature-icon span { position: relative; z-index: 1; }
.icon-level span { font-size: 13px; letter-spacing: -1px; }
.icon-audio { color: #0c8bb5; background: var(--sky-soft); font-size: 30px; }
.icon-word { color: #966300; background: var(--yellow-soft); font: 900 27px Georgia, serif; }
.icon-speak { color: white; background: #fff1e2; }
.icon-speak span { width: 26px; height: 19px; border-radius: 50%; background: var(--orange); font-size: 0; }
.icon-speak span::after { content: ""; position: absolute; left: 3px; bottom: -5px; border-width: 5px 6px 0 0; border-style: solid; border-color: var(--orange) transparent transparent transparent; transform: rotate(16deg); }
.feature-card h3 { margin: 0 0 10px; font-size: 21px; }
.feature-card p { margin: 0; color: var(--muted); font-size: 15px; }

.showcase { background: #f9fdfc; }
.showcase-row { position: relative; display: grid; grid-template-columns: minmax(0, 1.25fr) minmax(280px, .75fr); gap: 68px; align-items: center; margin: 0 0 116px; }
.showcase-row:last-child { margin-bottom: 0; }
.showcase-row.is-reversed { grid-template-columns: minmax(280px, .75fr) minmax(0, 1.25fr); }
.showcase-row.is-reversed .showcase-media { order: 2; }
.showcase-row.is-reversed .showcase-copy { order: 1; }
.showcase-media { position: relative; padding: 13px; border-radius: 30px; background: white; box-shadow: var(--shadow); }
.showcase-media::before { content: ""; position: absolute; z-index: -1; inset: -18px 25px 24px -18px; border-radius: 35px; background: var(--sky-soft); }
.is-reversed .showcase-media::before { inset: 22px -18px -18px 25px; background: var(--green-soft); }
.showcase-media img { width: 100%; border-radius: 19px; aspect-ratio: 844 / 390; object-fit: contain; background: #eaf8fb; }
.showcase-row:first-of-type .showcase-media img { aspect-ratio: 2048 / 941; }
.showcase-copy { position: relative; }
.step-number { position: absolute; right: 0; top: -25px; color: #dff0ec; font-size: 76px; font-weight: 900; line-height: 1; letter-spacing: -.08em; }
.mini-label { margin: 0 0 8px; color: var(--green-dark); font-size: 14px; font-weight: 800; }
.showcase-copy h3 { position: relative; margin: 0 0 14px; font-size: clamp(29px, 3vw, 40px); line-height: 1.25; letter-spacing: -.04em; }
.showcase-copy > p:not(.mini-label) { position: relative; margin: 0 0 22px; color: var(--muted); font-size: 16px; }
.detail-chip { display: inline-flex; padding: 7px 13px; border-radius: 999px; color: #407175; background: white; border: 1px solid var(--line); font-size: 13px; font-weight: 700; }

.intro { padding-bottom: 75px; }
.intro-card { position: relative; min-height: 330px; display: grid; grid-template-columns: .72fr 1.28fr; align-items: center; overflow: hidden; border-radius: 38px; background: var(--green-soft); }
.intro-copy { max-width: 650px; padding: 56px 70px 56px 20px; }
.intro-art { position: relative; align-self: stretch; min-height: 300px; overflow: hidden; }
.sun { position: absolute; width: 92px; height: 92px; border-radius: 50%; top: 45px; left: 90px; background: var(--yellow); box-shadow: 0 0 0 18px rgba(255,201,79,.15); }
.hill { position: absolute; border-radius: 50% 50% 0 0; bottom: -50px; }
.hill-one { width: 360px; height: 190px; left: -110px; background: #a3df8d; transform: rotate(8deg); }
.hill-two { width: 360px; height: 145px; left: 110px; background: #59c87b; transform: rotate(-8deg); }
.book { position: absolute; z-index: 2; left: 135px; bottom: 50px; display: grid; place-items: center; width: 90px; height: 72px; border-radius: 8px 8px 18px; border-bottom: 9px solid #ffb52f; background: #fff; color: var(--orange); font: 900 30px Georgia, serif; transform: rotate(-6deg); box-shadow: 0 10px 20px rgba(20,90,55,.16); }

.download { padding-top: 55px; }
.download-card { display: flex; align-items: center; justify-content: space-between; gap: 40px; padding: 58px 68px; border-radius: 36px; background: #effaff; box-shadow: inset 0 0 0 1px rgba(70,200,237,.10); }
.download-copy { max-width: 650px; }
.download h2 { font-size: clamp(30px, 3vw, 42px); }
.download-actions { display: flex; flex-direction: column; gap: 12px; flex: 0 0 210px; }
.store-button { display: flex; align-items: center; gap: 13px; min-height: 66px; padding: 10px 18px; border-radius: 17px; color: #fff; background: var(--ink); box-shadow: 0 10px 24px rgba(23,61,67,.16); font-size: 15px; font-weight: 800; line-height: 1.15; transition: transform .2s, box-shadow .2s; }
.store-button:hover, .store-button:focus-visible { transform: translateY(-3px); box-shadow: 0 14px 28px rgba(23,61,67,.22); }
.store-button small { display: block; margin-bottom: 3px; color: #cfe0e1; font-size: 9px; font-weight: 500; letter-spacing: .04em; }
.store-icon { display: grid; place-items: center; width: 31px; height: 31px; color: var(--yellow); font-size: 23px; }
.store-android .store-icon { color: #77d590; font-size: 22px; }

.site-footer { padding: 55px 0 22px; background: #fff; }
.footer-inner { display: flex; align-items: flex-start; justify-content: space-between; gap: 36px; padding-bottom: 35px; }
.footer-brand p { margin: 13px 0 0; color: var(--muted); font-size: 14px; }
.footer-contact { display: flex; flex-direction: column; align-items: flex-start; padding-top: 5px; color: var(--muted); font-size: 14px; }
.footer-contact a { color: #111; font-size: 16px; font-weight: 400; transition: color .2s; }
.footer-contact a:hover, .footer-contact a:focus-visible { color: var(--sky-dark); }
.footer-links { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 8px 25px; max-width: 570px; padding-top: 10px; }
.footer-links a { color: var(--muted); font-size: 14px; transition: color .2s; }
.footer-links a:hover, .footer-links a:focus-visible { color: var(--green-dark); }
.copyright { display: flex; justify-content: space-between; gap: 24px; padding-top: 20px; border-top: 1px solid var(--line); color: #8ba0a2; font-size: 13px; }

.reveal { opacity: 0; transform: translateY(22px); transition: opacity .65s ease, transform .65s ease; }
.reveal.is-visible { opacity: 1; transform: none; }

@media (max-width: 1050px) {
  :root { --header-height: 70px; }
  .hero { min-height: auto; padding-top: calc(var(--header-height) + 68px); }
  .hero-inner { grid-template-columns: 1fr 1.25fr; gap: 36px; }
  .hero h1 { font-size: 50px; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .feature-card { min-height: 220px; }
  .showcase-row, .showcase-row.is-reversed { gap: 45px; grid-template-columns: minmax(0, 1.15fr) minmax(260px, .85fr); }
  .intro-copy { padding-right: 45px; }
  .download-card { padding: 48px; }
}

@media (max-width: 780px) {
  .section-shell, .nav-wrap { width: min(100% - 32px, 1200px); }
  .nav-toggle { display: block; position: relative; z-index: 2; }
  .nav-toggle[aria-expanded="true"] span:first-child { transform: translateY(7px) rotate(45deg); }
  .nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
  .nav-toggle[aria-expanded="true"] span:last-child { transform: translateY(-7px) rotate(-45deg); }
  .site-nav { position: absolute; top: calc(100% + 8px); left: 16px; right: 16px; display: grid; padding: 12px; border: 1px solid var(--line); border-radius: 20px; background: rgba(255,255,255,.98); box-shadow: var(--shadow); opacity: 0; visibility: hidden; transform: translateY(-8px); transition: opacity .2s, transform .2s, visibility .2s; }
  .site-nav.is-open { opacity: 1; visibility: visible; transform: none; }
  .site-nav a { padding: 11px 14px; }
  .site-nav .nav-cta { margin: 3px 0 0; text-align: center; }
  .hero { padding: calc(var(--header-height) + 52px) 0 90px; }
  .hero-inner { grid-template-columns: 1fr; gap: 42px; }
  .hero-copy { text-align: center; }
  .hero h1 { font-size: clamp(43px, 12vw, 62px); }
  .hero-description { margin-inline: auto; }
  .hero-actions { justify-content: center; }
  .hero-visual { padding: 8px 2px 20px; }
  .badge-level { right: -7px; }
  .badge-read { left: -7px; }
  .section { padding: 78px 0; }
  .showcase-row, .showcase-row.is-reversed { grid-template-columns: 1fr; gap: 34px; margin-bottom: 86px; }
  .showcase-row .showcase-media, .showcase-row.is-reversed .showcase-media { order: 1; }
  .showcase-row .showcase-copy, .showcase-row.is-reversed .showcase-copy { order: 2; }
  .showcase-copy { padding-inline: 7px; }
  .step-number { top: -15px; font-size: 62px; }
  .intro-card { grid-template-columns: 1fr; }
  .intro-art { min-height: 230px; }
  .sun { left: 30%; }
  .hill-one { left: -30px; }
  .hill-two { left: 42%; }
  .book { left: 44%; bottom: 35px; }
  .intro-copy { padding: 40px 30px 46px; text-align: center; }
  .download-card { flex-direction: column; align-items: stretch; padding: 42px 30px; text-align: center; }
  .download-actions { flex: auto; width: min(230px, 100%); margin: auto; }
  .footer-inner { flex-direction: column; align-items: center; text-align: center; }
  .footer-contact { align-items: center; padding-top: 0; }
  .copyright { flex-direction: column; align-items: center; gap: 6px; text-align: center; }
  .footer-links { justify-content: center; padding-top: 0; }
}

@media (max-width: 500px) {
  .brand { font-size: 15px; }
  .brand-logo { width: 38px; height: 38px; border-radius: 12px; }
  .brand-mark { width: 36px; height: 36px; border-radius: 11px 11px 15px; font-size: 20px; }
  .hero-slogan { font-size: 22px; }
  .hero-description { font-size: 15px; }
  .hero-actions { gap: 10px; }
  .button { min-width: 116px; padding: 12px 19px; font-size: 14px; }
  .screenshot-window { border-width: 5px; border-radius: 20px; }
  .window-bar { height: 25px; }
  .window-bar span { display: none; }
  .visual-badge { padding: 7px 10px; border-width: 3px; border-radius: 13px; font-size: 11px; }
  .visual-badge b { width: 24px; height: 24px; border-radius: 8px; }
  .section-heading { margin-bottom: 36px; }
  .section-heading h2, .intro-copy h2, .download h2 { font-size: 30px; }
  .feature-grid { grid-template-columns: 1fr; gap: 14px; }
  .feature-card { min-height: 0; padding: 24px; }
  .feature-icon { width: 52px; height: 52px; margin-bottom: 18px; border-radius: 16px; }
  .showcase-media { padding: 7px; border-radius: 20px; }
  .showcase-media img { border-radius: 14px; }
  .showcase-media::before { inset: -11px 17px 15px -10px; border-radius: 25px; }
  .is-reversed .showcase-media::before { inset: 14px -10px -10px 17px; }
  .showcase-copy h3 { font-size: 28px; }
  .intro-card, .download-card { border-radius: 26px; }
  .intro-copy { padding-inline: 22px; }
  .download-card { padding-inline: 22px; }
  .footer-links { display: grid; grid-template-columns: 1fr 1fr; width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
  .reveal { opacity: 1; transform: none; }
}