/* 小乌龟英语阅读器 · 官网 v1.0 */
:root {
  --brand-green: #5b8c2a;
  --brand-green-dark: #3f6a1c;
  --brand-green-soft: #8fbf4a;
  --shell-green: #2f6b32;
  --accent-yellow: #f0c43a;
  --sky: #cfe9f5;
  --ink: #2a3324;
  --ink-soft: #5a6552;
  --paper: #fbfdf8;
  --nav-bg: rgba(251, 253, 248, 0.82);
  --line: rgba(91, 140, 42, 0.16);
  --shadow-soft: 0 18px 40px rgba(47, 107, 50, 0.12);
  --nav-h: 4.25rem;
  --footer-h: 5.25rem;
  --page-gutter: clamp(2rem, 8vw, 7rem);
  --content-max: 1040px;
  --screen-pad-y: 1.25rem;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --font-hero: "ZCOOL KuaiLe", "Fredoka", "Noto Sans SC", sans-serif;
  --font-display: "ZCOOL XiaoWei", "Fredoka", "Noto Sans SC", sans-serif;
  --font-body: "Nunito", "Noto Sans SC", sans-serif;
  --bg-garden: url("../assets/bg-garden.png");
  --bg-garden-overlay: linear-gradient(180deg, rgba(251, 253, 248, 0.42) 0%, rgba(251, 253, 248, 0.68) 100%);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  height: 100%;
}

html.home-snap {
  scroll-snap-type: y mandatory;
  overscroll-behavior: none;
}

body {
  margin: 0;
  min-height: 100%;
  color: var(--ink);
  font-family: var(--font-body);
  font-weight: 500;
  line-height: 1.65;
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--brand-green-dark);
  text-decoration: none;
}

a:hover {
  color: var(--brand-green);
}

.site-header {
  position: fixed;
  inset: 0 0 auto;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0 var(--page-gutter);
  background: var(--nav-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
  transition: background 0.35s var(--ease), box-shadow 0.35s var(--ease);
}

.site-header.is-scrolled {
  box-shadow: 0 8px 24px rgba(42, 51, 36, 0.06);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  color: var(--ink);
  font-family: var(--font-display);
  font-size: clamp(1.05rem, 2.2vw, 1.25rem);
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.brand img {
  width: 2.25rem;
  height: 2.25rem;
  object-fit: contain;
  border-radius: 0.45rem;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: clamp(0.75rem, 2vw, 1.5rem);
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--ink-soft);
  font-size: 0.95rem;
  font-weight: 700;
  position: relative;
  padding: 0.25rem 0;
  transition: color 0.25s var(--ease);
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -0.2rem;
  height: 2px;
  border-radius: 999px;
  background: var(--brand-green);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 0.28s var(--ease);
}

.nav-links a:hover,
.nav-links a.is-active {
  color: var(--brand-green-dark);
}

.nav-links a.is-active::after {
  transform: scaleX(1);
}

.nav-legal {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--ink-soft);
  white-space: nowrap;
}

.nav-legal a {
  color: inherit;
}

.nav-legal span {
  opacity: 0.35;
}

.nav-toggle {
  display: none;
  width: 2.5rem;
  height: 2.5rem;
  border: 0;
  border-radius: 0.75rem;
  background: rgba(91, 140, 42, 0.12);
  cursor: pointer;
  align-items: center;
  justify-content: center;
}

.nav-toggle span,
.nav-toggle span::before,
.nav-toggle span::after {
  display: block;
  width: 1.1rem;
  height: 2px;
  background: var(--shell-green);
  border-radius: 2px;
  position: relative;
}

.nav-toggle span::before,
.nav-toggle span::after {
  content: "";
  position: absolute;
  left: 0;
}

.nav-toggle span::before {
  top: -5px;
}

.nav-toggle span::after {
  top: 5px;
}

.page-dots {
  position: fixed;
  right: calc(var(--page-gutter) * 0.45);
  top: 50%;
  transform: translateY(-50%);
  z-index: 90;
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}

.page-dots button {
  width: 0.55rem;
  height: 0.55rem;
  padding: 0;
  border: 0;
  border-radius: 999px;
  background: rgba(91, 140, 42, 0.28);
  cursor: pointer;
  transition: transform 0.25s var(--ease), background 0.25s var(--ease), height 0.25s var(--ease);
}

.page-dots button.is-active {
  height: 1.35rem;
  background: var(--brand-green);
}

.page-turn {
  position: fixed;
  left: 50%;
  z-index: 96;
  transform: translateX(-50%);
  display: grid;
  place-items: center;
  width: auto;
  height: auto;
  padding: 0.2rem 0.45rem;
  border: 0;
  background: transparent;
  color: var(--brand-green);
  cursor: pointer;
  opacity: 0.82;
  transition: opacity 0.25s var(--ease), color 0.25s var(--ease);
}

.page-turn-up {
  top: calc(var(--nav-h) + 0.35rem);
}

.page-turn-down {
  bottom: calc(var(--footer-h) + 0.35rem);
}

.page-turn-icon {
  display: inline-block;
  font-size: clamp(1.35rem, 2.4vw, 1.65rem);
  line-height: 1;
  font-weight: 800;
  text-shadow: 0 1px 10px rgba(251, 253, 248, 0.85);
}

.page-turn-up .page-turn-icon {
  transform: rotate(-90deg);
}

.page-turn-down .page-turn-icon {
  transform: rotate(90deg);
}

.page-turn:hover:not(:disabled) {
  opacity: 1;
  color: var(--brand-green-dark);
}

.page-turn:disabled {
  opacity: 0;
  pointer-events: none;
}

.page-turn-up:not(:disabled) .page-turn-icon {
  animation: nudge-up 1.8s var(--ease) infinite;
}

.page-turn-down:not(:disabled) .page-turn-icon {
  animation: nudge-down-icon 1.8s var(--ease) infinite;
}

@keyframes nudge-up {
  0%,
  100% {
    transform: rotate(-90deg) translateX(0);
  }

  50% {
    transform: rotate(-90deg) translateX(-4px);
  }
}

@keyframes nudge-down-icon {
  0%,
  100% {
    transform: rotate(90deg) translateX(0);
  }

  50% {
    transform: rotate(90deg) translateX(4px);
  }
}

.screen {
  height: 100vh;
  height: 100dvh;
  min-height: 100dvh;
  max-height: 100dvh;
  scroll-snap-align: start;
  scroll-snap-stop: always;
  position: relative;
  display: flex;
  align-items: stretch;
  padding:
    calc(var(--nav-h) + var(--screen-pad-y))
    var(--page-gutter)
    calc(var(--footer-h) + var(--screen-pad-y));
  overflow: hidden;
  background:
    var(--bg-garden-overlay),
    var(--bg-garden) top right / cover no-repeat;
}

.screen-inner {
  position: relative;
  z-index: 1;
  width: min(var(--content-max), 100%);
  max-height: 100%;
  margin: 0 auto;
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
  scrollbar-color: rgba(91, 140, 42, 0.35) transparent;
}

.screen-inner::-webkit-scrollbar {
  width: 4px;
}

.screen-inner::-webkit-scrollbar-thumb {
  background: rgba(91, 140, 42, 0.35);
  border-radius: 999px;
}

.hero {
  color: var(--ink);
}

.hero-bg {
  display: none;
}

.hero .screen-inner {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: clamp(1.25rem, 4vw, 3.5rem);
  align-items: center;
}

.hero-copy {
  max-width: 34rem;
}

.hero-brand {
  margin: 0 0 0.75rem;
  font-family: var(--font-hero);
  font-size: clamp(2.4rem, 5.8vw, 4.6rem);
  font-weight: 400;
  line-height: 1.06;
  letter-spacing: 0.06em;
  color: var(--shell-green);
  text-shadow: 0 2px 0 rgba(255, 255, 255, 0.45);
  opacity: 0;
  transform: translateY(18px);
  animation: rise-in 0.9s var(--ease) 0.15s forwards;
}

.hero-slogan {
  margin: 0 0 0.85rem;
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 2.6vw, 1.85rem);
  color: var(--brand-green-dark);
  opacity: 0;
  transform: translateY(18px);
  animation: rise-in 0.9s var(--ease) 0.3s forwards;
}

.hero-lead {
  margin: 0 0 1.5rem;
  font-size: clamp(0.98rem, 1.8vw, 1.12rem);
  color: var(--ink-soft);
  max-width: 28rem;
  opacity: 0;
  transform: translateY(18px);
  animation: rise-in 0.9s var(--ease) 0.45s forwards;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  min-height: 2.85rem;
  padding: 0.7rem 1.35rem;
  border-radius: 999px;
  border: 0;
  background: var(--brand-green);
  color: #fff;
  font-family: inherit;
  font-size: clamp(0.95rem, 1.6vw, 1rem);
  font-weight: 800;
  cursor: pointer;
  box-shadow: 0 12px 28px rgba(91, 140, 42, 0.28);
  transition: transform 0.25s var(--ease), background 0.25s var(--ease);
  opacity: 0;
  transform: translateY(18px);
  animation: rise-in 0.9s var(--ease) 0.6s forwards;
}

.btn:hover {
  background: var(--brand-green-dark);
  transform: translateY(-2px);
  color: #fff;
}

.btn-arrow {
  font-size: 1.15rem;
  line-height: 1;
}

.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
  opacity: 0;
  transform: translateY(24px) scale(0.96);
  animation: rise-in 1s var(--ease) 0.35s forwards;
}

.hero-visual img {
  width: min(380px, 100%);
  max-height: min(52vh, 420px);
  object-fit: contain;
  filter: drop-shadow(0 24px 36px rgba(47, 107, 50, 0.18));
}

.section-kicker {
  margin: 0 0 0.45rem;
  color: var(--brand-green);
  font-size: clamp(0.82rem, 1.4vw, 0.9rem);
  font-weight: 800;
  letter-spacing: 0.08em;
}

.section-title {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: clamp(1.65rem, 3.6vw, 2.5rem);
  line-height: 1.18;
  color: var(--shell-green);
}

.section-lead {
  margin: 0 0 1.25rem;
  color: var(--ink-soft);
  font-size: clamp(0.95rem, 1.7vw, 1.05rem);
  max-width: 36rem;
}

.product .screen-inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(1.25rem, 3.5vw, 3rem);
  align-items: center;
}

.point-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: clamp(0.75rem, 1.8vw, 1rem);
}

.point-list li {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.75rem;
  align-items: start;
}

.point-index {
  width: 1.85rem;
  height: 1.85rem;
  border-radius: 999px;
  display: grid;
  place-items: center;
  background: rgba(91, 140, 42, 0.14);
  color: var(--brand-green-dark);
  font-weight: 800;
  font-size: 0.85rem;
}

.point-list strong {
  display: block;
  margin-bottom: 0.1rem;
  color: var(--ink);
  font-size: clamp(0.95rem, 1.6vw, 1rem);
}

.point-list span {
  color: var(--ink-soft);
  font-size: clamp(0.88rem, 1.5vw, 0.95rem);
}

.product-shots {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(0.75rem, 2vw, 1rem);
  align-items: end;
}

.product-shots img {
  width: 100%;
  max-height: min(42vh, 360px);
  object-fit: contain;
  border-radius: 1.25rem;
  box-shadow: var(--shadow-soft);
  border: 3px solid rgba(255, 255, 255, 0.85);
}

.product-shots img:first-child {
  transform: translateY(0.8rem);
}

.steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(0.75rem, 2.5vw, 1.75rem);
  margin-top: 0.25rem;
}

.step {
  text-align: center;
  padding: 0.25rem;
}

.step img {
  width: min(130px, 48%);
  max-height: min(18vh, 140px);
  margin: 0 auto 0.75rem;
  object-fit: contain;
  filter: drop-shadow(0 14px 20px rgba(47, 107, 50, 0.12));
}

.step h3 {
  margin: 0 0 0.35rem;
  font-family: var(--font-display);
  font-size: clamp(1.05rem, 2vw, 1.2rem);
  color: var(--shell-green);
}

.step p {
  margin: 0;
  color: var(--ink-soft);
  font-size: clamp(0.88rem, 1.5vw, 0.96rem);
}

.feature-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: clamp(0.65rem, 1.8vw, 1rem);
  margin-bottom: clamp(1rem, 2.5vw, 1.5rem);
}

.feature-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.45rem;
  text-align: center;
  color: var(--ink);
  font-weight: 700;
  font-size: clamp(0.88rem, 1.5vw, 0.98rem);
}

.feature-item img {
  width: clamp(2.5rem, 5vw, 3.1rem);
  height: clamp(2.5rem, 5vw, 3.1rem);
  object-fit: contain;
}

.gallery {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(0.65rem, 1.8vw, 1rem);
}

.gallery img {
  width: 100%;
  max-height: min(28vh, 220px);
  object-fit: contain;
  border-radius: 1.1rem;
  box-shadow: var(--shadow-soft);
  border: 3px solid rgba(255, 255, 255, 0.9);
}

.about .screen-inner {
  justify-content: center;
  gap: clamp(1rem, 2.5vw, 1.75rem);
}

.about-top {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 0.8fr);
  gap: clamp(1.25rem, 3vw, 2rem);
  align-items: center;
  flex: 1;
  min-height: 0;
}

.about-visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.about-visual img {
  width: min(240px, 100%);
  max-height: min(32vh, 260px);
  object-fit: contain;
  filter: drop-shadow(0 18px 28px rgba(47, 107, 50, 0.14));
}

.site-footer {
  position: fixed;
  inset: auto 0 0;
  z-index: 95;
  padding: 0.7rem var(--page-gutter);
  background: rgba(251, 253, 248, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-top: 1px solid var(--line);
  color: var(--ink-soft);
  font-size: clamp(0.78rem, 1.3vw, 0.88rem);
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr);
  gap: clamp(0.65rem, 2vw, 1rem);
  width: min(var(--content-max), 100%);
  margin: 0 auto;
  align-items: center;
}

.site-footer p {
  margin: 0 0 0.2rem;
}

.site-footer strong {
  color: var(--ink);
  font-weight: 800;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem 0.85rem;
  margin: 0 0 0.35rem;
  justify-content: flex-end;
}

.icp {
  margin: 0;
  font-size: clamp(0.75rem, 1.2vw, 0.82rem);
  text-align: right;
}

.reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
}

.screen.is-inview .reveal,
.reveal.is-shown {
  opacity: 1;
  transform: translateY(0);
}

.screen.is-inview .reveal-delay-1 {
  transition-delay: 0.08s;
}

.screen.is-inview .reveal-delay-2 {
  transition-delay: 0.16s;
}

.screen.is-inview .reveal-delay-3 {
  transition-delay: 0.24s;
}

@keyframes rise-in {
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

/* Legal pages */
.legal-body {
  background:
    var(--bg-garden-overlay),
    var(--bg-garden) top right / cover no-repeat fixed;
  min-height: 100vh;
}

.legal-main {
  width: min(820px, calc(100% - var(--page-gutter) * 2));
  margin: 0 auto;
  padding: calc(var(--nav-h) + 2.5rem) 0 3.5rem;
}

.legal-main h1 {
  margin: 0 0 0.5rem;
  font-family: var(--font-hero);
  font-size: clamp(1.85rem, 4vw, 2.5rem);
  font-weight: 400;
  letter-spacing: 0.04em;
  color: var(--shell-green);
}

.legal-updated {
  margin: 0 0 2rem;
  color: var(--ink-soft);
  font-size: 0.92rem;
}

.legal-main h2 {
  margin: 1.75rem 0 0.65rem;
  font-size: 1.15rem;
  color: var(--brand-green-dark);
}

.legal-main p,
.legal-main li {
  color: var(--ink-soft);
  font-size: 0.98rem;
}

.legal-main ul {
  padding-left: 1.2rem;
}

.legal-footer {
  width: min(820px, calc(100% - var(--page-gutter) * 2));
  margin: 0 auto 2.5rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
  color: var(--ink-soft);
  font-size: 0.88rem;
}

.legal-nav .nav-links {
  display: none;
}

.legal-nav .nav-legal {
  display: flex;
}

.legal-nav .nav-toggle {
  display: none;
}

@media (max-width: 960px) {
  :root {
    --page-gutter: clamp(1.75rem, 6.5vw, 3rem);
  }

  .hero .screen-inner,
  .product .screen-inner,
  .about-top,
  .footer-grid {
    grid-template-columns: 1fr;
  }

  .hero-visual {
    order: -1;
  }

  .hero-visual img {
    max-height: min(28vh, 220px);
  }

  .hero-brand {
    font-size: clamp(2rem, 9vw, 3rem);
  }

  .steps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .feature-row {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .gallery {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-dots {
    display: none;
  }
}

@media (max-width: 720px) {
  :root {
    --page-gutter: clamp(1.5rem, 6vw, 2.25rem);
    --screen-pad-y: 0.85rem;
    --footer-h: 7.5rem;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .nav-links,
  .nav-legal {
    display: none;
  }

  .legal-nav .nav-legal {
    display: flex;
  }

  .site-header.is-open .nav-links,
  .site-header.is-open .nav-legal {
    display: flex;
  }

  .site-header.is-open {
    flex-wrap: wrap;
    height: auto;
    padding-top: 0.85rem;
    padding-bottom: 1rem;
  }

  .site-header.is-open .nav-links {
    width: 100%;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.85rem;
    padding-top: 0.75rem;
  }

  .site-header.is-open .nav-legal {
    width: 100%;
    padding-top: 0.35rem;
  }

  .hero .screen-inner {
    gap: 0.85rem;
  }

  .steps {
    grid-template-columns: 1fr;
    gap: 0.65rem;
  }

  .step {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 0.75rem;
    text-align: left;
    align-items: center;
  }

  .step img {
    width: 72px;
    max-height: 72px;
    margin: 0;
  }

  .feature-row {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .gallery {
    grid-template-columns: 1fr 1fr;
  }

  .gallery img:last-child {
    grid-column: 1 / -1;
    max-height: min(24vh, 180px);
    justify-self: center;
    width: min(320px, 100%);
  }

  .product-shots {
    max-width: 360px;
    margin: 0 auto;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 0.55rem;
  }

  .footer-links,
  .icp {
    justify-content: flex-start;
    text-align: left;
  }
}

@media (max-height: 760px) and (min-width: 721px) {
  .hero-brand {
    font-size: clamp(2rem, 4.8vw, 3.2rem);
  }

  .hero-visual img {
    max-height: min(44vh, 320px);
  }

  .section-title {
    font-size: clamp(1.45rem, 3vw, 2rem);
  }

  .section-lead {
    margin-bottom: 0.85rem;
  }

  .gallery img {
    max-height: min(22vh, 170px);
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .page-turn-up:not(:disabled) .page-turn-icon,
  .page-turn-down:not(:disabled) .page-turn-icon {
    animation: none;
  }

  .hero-brand,
  .hero-slogan,
  .hero-lead,
  .btn,
  .hero-visual,
  .reveal {
    animation: none;
    opacity: 1;
    transform: none;
    transition: none;
  }
}