:root {
  --ink: #171a23;
  --paper: #f7f7f2;
  --white: #ffffff;
  --teal: #00b8a9;
  --teal-dark: #007f78;
  --coral: #ff5f57;
  --yellow: #ffd166;
  --line: #d9dbd6;
  --muted: #626873;
  --shadow: 8px 8px 0 var(--ink);
  --max: 1160px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
  line-height: 1.75;
}

body::before {
  position: fixed;
  inset: 0;
  z-index: -2;
  content: "";
  background-image: radial-gradient(#171a23 0.8px, transparent 0.8px);
  background-size: 18px 18px;
  opacity: 0.06;
}

a {
  color: inherit;
  text-decoration: none;
}

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

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 100;
  padding: 8px 14px;
  background: var(--white);
  border: 2px solid var(--ink);
  transform: translateY(-150%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  background: rgba(247, 247, 242, 0.95);
  border-bottom: 3px solid var(--ink);
  backdrop-filter: blur(12px);
}

.nav-wrap {
  width: min(calc(100% - 32px), var(--max));
  min-height: 74px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 900;
  font-size: 22px;
}

.brand img {
  width: 44px;
  height: 44px;
  border: 2px solid var(--ink);
  border-radius: 8px;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 6px;
}

.site-nav a {
  padding: 9px 13px;
  font-weight: 700;
  border-bottom: 3px solid transparent;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--teal-dark);
  border-color: var(--teal);
}

.menu-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  background: var(--white);
  border: 2px solid var(--ink);
  border-radius: 6px;
  font-size: 24px;
  cursor: pointer;
}

.download-btn,
.text-link {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 22px;
  font-weight: 900;
  border: 3px solid var(--ink);
  border-radius: 6px;
  transition: transform 160ms ease, box-shadow 160ms ease;
}

.download-btn {
  color: var(--white);
  background: var(--coral);
  box-shadow: 5px 5px 0 var(--ink);
}

.download-btn::after {
  content: "↓";
  font-size: 20px;
}

.download-btn:hover,
.text-link:hover {
  transform: translate(3px, 3px);
  box-shadow: 2px 2px 0 var(--ink);
}

.hero {
  overflow: hidden;
  border-bottom: 3px solid var(--ink);
  background: linear-gradient(105deg, var(--teal) 0 58%, var(--yellow) 58% 100%);
}

.hero-grid {
  width: min(calc(100% - 32px), var(--max));
  min-height: 620px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  align-items: center;
  gap: 52px;
  padding: 64px 0 54px;
}

.eyebrow,
.chapter-tag {
  display: inline-block;
  margin: 0 0 16px;
  padding: 5px 11px;
  font-size: 14px;
  font-weight: 900;
  background: var(--yellow);
  border: 2px solid var(--ink);
  transform: rotate(-1deg);
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1,
h2,
h3 {
  line-height: 1.2;
  letter-spacing: 0;
}

h1 {
  max-width: 720px;
  margin-bottom: 20px;
  font-size: 68px;
  font-weight: 1000;
}

h2 {
  margin-bottom: 28px;
  font-size: 42px;
}

h3 {
  margin-bottom: 10px;
  font-size: 21px;
}

.hero-copy > p:not(.eyebrow) {
  max-width: 640px;
  margin-bottom: 26px;
  font-size: 18px;
  font-weight: 600;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
}

.hero-actions .text-link {
  background: var(--white);
  box-shadow: 5px 5px 0 var(--ink);
}

.device-notes {
  margin-top: 24px;
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
}

.device-notes span {
  padding: 5px 10px;
  font-size: 13px;
  font-weight: 800;
  background: rgba(255, 255, 255, 0.8);
  border: 2px solid var(--ink);
}

.hero-visual {
  position: relative;
  min-height: 500px;
}

.phone {
  position: absolute;
  width: min(260px, 62vw);
  padding: 10px;
  background: var(--ink);
  border: 3px solid var(--ink);
  border-radius: 22px;
  box-shadow: var(--shadow);
}

.phone img {
  width: 100%;
  max-width: 400px;
  height: auto;
  border-radius: 13px;
}

.phone-primary {
  top: 6px;
  left: 6%;
  transform: rotate(-5deg);
}

.phone-secondary {
  right: 4%;
  bottom: 0;
  transform: rotate(6deg);
}

.sound-effect {
  position: absolute;
  top: 5%;
  right: 2%;
  padding: 6px 12px;
  background: var(--coral);
  color: var(--white);
  border: 3px solid var(--ink);
  font-size: 24px;
  font-weight: 1000;
  transform: rotate(8deg);
}

.stats-strip {
  background: var(--ink);
  color: var(--white);
}

.stats-grid {
  width: min(calc(100% - 32px), var(--max));
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}

.stat {
  min-height: 108px;
  display: grid;
  place-content: center;
  text-align: center;
  border-left: 1px solid #4a4d56;
}

.stat:last-child {
  border-right: 1px solid #4a4d56;
}

.stat strong {
  color: var(--yellow);
  font-size: 24px;
}

.stat span {
  font-size: 13px;
  color: #d6d8dd;
}

.section {
  padding: 86px 0;
  border-bottom: 3px solid var(--ink);
}

.section-inner {
  width: min(calc(100% - 32px), var(--max));
  margin: 0 auto;
}

.section-head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 34px;
}

.section-head h2 {
  margin-bottom: 0;
}

.section-index {
  flex: none;
  font-size: 52px;
  font-weight: 1000;
  color: var(--teal);
  line-height: 1;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 22px;
}

.feature-card,
.path-card,
.quote-card,
.info-panel {
  background: var(--white);
  border: 3px solid var(--ink);
  border-radius: 7px;
}

.feature-card {
  min-height: 220px;
  padding: 28px;
  position: relative;
  overflow: hidden;
}

.feature-card:nth-child(2) {
  background: #e7faf8;
}

.feature-card:nth-child(3) {
  background: #fff3ef;
}

.feature-card:nth-child(4) {
  background: #fff7d9;
}

.feature-icon {
  width: 48px;
  height: 48px;
  margin-bottom: 20px;
  display: grid;
  place-items: center;
  background: var(--ink);
  color: var(--white);
  border-radius: 50%;
  font-size: 22px;
  font-weight: 900;
}

.feature-card p,
.path-card p,
.quote-card p,
.article-block p,
.faq-answer p {
  color: var(--muted);
}

.screens {
  background: var(--teal);
}

.screen-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 20px;
  align-items: end;
}

.app-shot {
  margin: 0;
}

.app-shot img {
  width: min(100%, 360px);
  max-width: 400px;
  height: auto;
  margin: 0 auto;
  border: 8px solid var(--ink);
  border-radius: 18px;
  box-shadow: 6px 6px 0 rgba(23, 26, 35, 0.35);
}

.app-shot figcaption {
  margin-top: 14px;
  padding: 8px 10px;
  text-align: center;
  font-weight: 800;
  background: var(--white);
  border: 2px solid var(--ink);
}

.path-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.path-card {
  padding: 32px;
  box-shadow: var(--shadow);
}

.path-card .chapter-tag {
  margin-bottom: 22px;
}

.path-card ul,
.check-list {
  margin: 20px 0 24px;
  padding: 0;
  list-style: none;
}

.path-card li,
.check-list li {
  position: relative;
  margin-bottom: 10px;
  padding-left: 28px;
}

.path-card li::before,
.check-list li::before {
  position: absolute;
  left: 0;
  content: "✓";
  color: var(--teal-dark);
  font-weight: 1000;
}

.quote-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.quote-card {
  padding: 26px;
}

.quote-card blockquote {
  margin: 0 0 18px;
  font-size: 17px;
}

.quote-card cite {
  color: var(--teal-dark);
  font-style: normal;
  font-weight: 900;
}

.rating {
  color: #c44b00;
  letter-spacing: 0;
}

.download-band {
  background: var(--yellow);
}

.download-band .section-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
}

.download-band h2 {
  margin-bottom: 8px;
}

.download-band p {
  margin-bottom: 0;
  font-weight: 700;
}

.page-hero {
  padding: 74px 0 66px;
  background: var(--teal);
  border-bottom: 3px solid var(--ink);
}

.page-hero.yellow {
  background: var(--yellow);
}

.page-hero .section-inner {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: end;
  gap: 30px;
}

.page-hero h1 {
  margin-bottom: 16px;
  font-size: 60px;
}

.page-hero p {
  max-width: 760px;
  margin-bottom: 0;
  font-size: 18px;
  font-weight: 700;
}

.guide-layout,
.faq-layout {
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  gap: 44px;
}

.side-index {
  align-self: start;
  position: sticky;
  top: 102px;
  padding: 22px;
  background: var(--white);
  border: 3px solid var(--ink);
}

.side-index strong {
  display: block;
  margin-bottom: 12px;
  font-size: 18px;
}

.side-index a {
  display: block;
  padding: 8px 0;
  color: var(--muted);
  border-bottom: 1px solid var(--line);
}

.side-index a:hover {
  color: var(--teal-dark);
}

.article-block {
  scroll-margin-top: 100px;
  margin-bottom: 36px;
  padding: 30px;
  background: var(--white);
  border: 3px solid var(--ink);
}

.article-block.article-flat {
  padding: 0;
  background: transparent;
  border: 0;
}

.article-block h2 {
  font-size: 30px;
  margin-bottom: 22px;
}

.step-number {
  float: right;
  color: var(--coral);
  font-size: 54px;
  font-weight: 1000;
  line-height: 0.8;
}

.article-media {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(180px, 280px);
  align-items: center;
  gap: 28px;
}

.article-media img {
  width: min(100%, 340px);
  max-width: 400px;
  height: auto;
  margin: 0 auto;
  border: 6px solid var(--ink);
  border-radius: 14px;
}

.notice {
  margin: 20px 0;
  padding: 16px 18px;
  background: #fff4d1;
  border-left: 6px solid var(--coral);
  font-weight: 700;
}

.faq-list {
  display: grid;
  gap: 14px;
}

.faq-item {
  background: var(--white);
  border: 3px solid var(--ink);
}

.faq-question {
  width: 100%;
  min-height: 66px;
  padding: 16px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  color: var(--ink);
  background: transparent;
  border: 0;
  font: inherit;
  font-size: 17px;
  font-weight: 900;
  text-align: left;
  cursor: pointer;
}

.faq-question::after {
  flex: none;
  content: "+";
  font-size: 28px;
}

.faq-item.open .faq-question::after {
  content: "−";
}

.faq-answer {
  display: none;
  padding: 0 20px 18px;
}

.faq-item.open .faq-answer {
  display: block;
}

.faq-answer p:last-child {
  margin-bottom: 0;
}

.site-footer {
  padding: 48px 0 24px;
  color: #dfe1e5;
  background: var(--ink);
}

.footer-grid {
  width: min(calc(100% - 32px), var(--max));
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.3fr 0.7fr 0.7fr;
  gap: 32px;
}

.footer-brand {
  color: var(--white);
}

.footer-brand p {
  max-width: 520px;
  margin-top: 16px;
  color: #aeb2bc;
}

.footer-links strong {
  display: block;
  margin-bottom: 12px;
  color: var(--yellow);
}

.footer-links a {
  display: block;
  padding: 5px 0;
}

.footer-bottom {
  width: min(calc(100% - 32px), var(--max));
  margin: 34px auto 0;
  padding-top: 20px;
  color: #aeb2bc;
  border-top: 1px solid #444852;
  font-size: 13px;
}

.footer-bottom p {
  margin-bottom: 8px;
}

@media (max-width: 860px) {
  .menu-toggle {
    display: block;
  }

  .site-nav {
    display: none;
    position: absolute;
    top: 74px;
    left: 0;
    right: 0;
    padding: 16px;
    flex-direction: column;
    align-items: stretch;
    background: var(--paper);
    border-bottom: 3px solid var(--ink);
  }

  .site-nav.open {
    display: flex;
  }

  .site-nav a {
    text-align: center;
  }

  .hero {
    background: var(--teal);
  }

  .hero-grid,
  .page-hero .section-inner {
    grid-template-columns: 1fr;
  }

  .hero-grid {
    padding-top: 48px;
  }

  h1 {
    font-size: 52px;
  }

  h2 {
    font-size: 36px;
  }

  .page-hero h1 {
    font-size: 50px;
  }

  .hero-visual {
    min-height: 470px;
    background: var(--yellow);
    border: 3px solid var(--ink);
  }

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

  .feature-grid,
  .path-grid,
  .quote-grid {
    grid-template-columns: 1fr;
  }

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

  .guide-layout,
  .faq-layout {
    grid-template-columns: 1fr;
  }

  .side-index {
    position: static;
  }

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

@media (max-width: 560px) {
  .nav-wrap {
    min-height: 66px;
  }

  .brand img {
    width: 40px;
    height: 40px;
  }

  .site-nav {
    top: 66px;
  }

  h1 {
    font-size: 42px;
  }

  h2 {
    font-size: 30px;
  }

  .page-hero h1 {
    font-size: 40px;
  }

  .hero-grid {
    min-height: auto;
  }

  .hero-visual {
    min-height: 420px;
  }

  .phone {
    width: 210px;
  }

  .phone-primary {
    left: 4%;
  }

  .phone-secondary {
    right: 4%;
  }

  .sound-effect {
    top: 2%;
    right: 1%;
    font-size: 18px;
  }

  .stats-grid,
  .screen-row,
  .footer-grid {
    grid-template-columns: 1fr;
  }

  .stat,
  .stat:last-child {
    border-right: 0;
    border-left: 0;
    border-bottom: 1px solid #4a4d56;
  }

  .section {
    padding: 62px 0;
  }

  .section-head {
    align-items: flex-start;
  }

  .section-index {
    font-size: 34px;
  }

  .article-media {
    grid-template-columns: 1fr;
  }

  .download-band .section-inner {
    align-items: stretch;
    flex-direction: column;
  }

  .download-btn,
  .text-link {
    width: 100%;
  }
}

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

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
  }
}