:root {
  --ink: #17171a;
  --paper: #f7fbf8;
  --white: #ffffff;
  --mint: #36d399;
  --mint-dark: #087f5b;
  --coral: #ff6b5e;
  --yellow: #ffd166;
  --sky: #dff3ff;
  --line: #17171a;
  --muted: #60666b;
  --shadow: 6px 6px 0 var(--ink);
  --max: 1180px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  overflow-x: hidden;
  color: var(--ink);
  background: var(--paper);
  font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.75;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: .22;
  background-image: radial-gradient(#17171a 0.65px, transparent 0.65px);
  background-size: 12px 12px;
  z-index: -1;
}

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button, a { -webkit-tap-highlight-color: transparent; }

.skip-link {
  position: fixed;
  left: 12px;
  top: -80px;
  z-index: 99;
  padding: 8px 14px;
  background: var(--ink);
  color: #fff;
}
.skip-link:focus { top: 12px; }

.container { width: min(calc(100% - 40px), var(--max)); margin-inline: auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 2px solid var(--ink);
  background: rgba(247, 251, 248, .96);
  backdrop-filter: blur(10px);
}

.nav-wrap {
  min-height: 76px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 900; }
.brand img { width: 48px; height: 48px; border: 2px solid var(--ink); border-radius: 8px; }
.brand-name { font-size: 20px; letter-spacing: 0; white-space: nowrap; }
.nav-links { display: flex; align-items: center; gap: 6px; }
.nav-links a { padding: 8px 13px; font-weight: 700; border-bottom: 3px solid transparent; }
.nav-links a:hover, .nav-links a[aria-current="page"] { border-color: var(--coral); }
.menu-toggle {
  display: none;
  width: 42px;
  height: 42px;
  border: 2px solid var(--ink);
  border-radius: 6px;
  background: var(--yellow);
  font-size: 24px;
  line-height: 1;
  cursor: pointer;
}

.button {
  min-height: 46px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 22px;
  border: 2px solid var(--ink);
  border-radius: 6px;
  background: var(--coral);
  color: #fff;
  font-weight: 900;
  box-shadow: 4px 4px 0 var(--ink);
  transition: transform .18s ease, box-shadow .18s ease;
}
.button::after { content: "↓"; font-size: 18px; }
.button:hover { transform: translate(2px, 2px); box-shadow: 2px 2px 0 var(--ink); }
.button:focus-visible, .nav-links a:focus-visible, summary:focus-visible { outline: 3px solid var(--mint-dark); outline-offset: 3px; }
.button-dark { background: var(--ink); }
.button-small { min-height: 40px; padding: 7px 15px; box-shadow: none; }

.hero {
  overflow: hidden;
  border-bottom: 2px solid var(--ink);
  background: var(--sky);
}

.hero-grid {
  min-height: 620px;
  display: grid;
  grid-template-columns: minmax(0, 1.03fr) minmax(430px, .97fr);
  align-items: center;
  gap: 48px;
  padding-block: 64px 54px;
}

.eyebrow, .section-kicker {
  display: inline-block;
  margin: 0 0 12px;
  padding: 4px 11px;
  border: 2px solid var(--ink);
  background: var(--yellow);
  font-size: 14px;
  font-weight: 900;
  transform: rotate(-1deg);
}

h1, h2, h3 { max-width: 100%; margin-top: 0; line-height: 1.22; letter-spacing: 0; overflow-wrap: anywhere; }
h1 { margin-bottom: 22px; font-size: 76px; }
h2 { margin-bottom: 28px; font-size: 42px; }
h3 { margin-bottom: 10px; font-size: 21px; }
.hero-copy > p:not(.eyebrow) { max-width: 620px; margin: 0 0 24px; color: #3e464b; font-size: 18px; }
.hero-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 18px; }
.microcopy { font-size: 13px; color: var(--muted); font-weight: 700; }
.hero-tags { display: flex; align-items: center; flex-wrap: wrap; gap: 7px; }
.hero-tag { padding: 3px 9px; border: 1px solid var(--ink); border-radius: 4px; background: var(--white); font-size: 12px; font-weight: 700; white-space: nowrap; }
.quote-meta { display: block; margin-top: 6px; font-size: 12px; }

.phone-stage { position: relative; min-height: 500px; }
.phone {
  position: absolute;
  width: min(250px, 54%);
  padding: 9px;
  border: 3px solid var(--ink);
  border-radius: 28px;
  background: var(--ink);
  box-shadow: 10px 12px 0 rgba(23,23,26,.18);
}
.phone img { width: 100%; max-width: 400px; height: auto; border-radius: 18px; }
.phone-main { left: 15%; top: 0; z-index: 2; transform: rotate(-4deg); }
.phone-side { right: 0; bottom: 0; transform: rotate(6deg); }
.burst {
  position: absolute;
  right: 0;
  top: 10px;
  width: 116px;
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  padding: 20px;
  background: var(--yellow);
  border: 2px solid var(--ink);
  clip-path: polygon(50% 0,61% 25%,85% 15%,75% 39%,100% 50%,75% 61%,85% 85%,61% 75%,50% 100%,39% 75%,15% 85%,25% 61%,0 50%,25% 39%,15% 15%,39% 25%);
  font-weight: 900;
  text-align: center;
  line-height: 1.2;
  z-index: 3;
}

.signal-strip { border-bottom: 2px solid var(--ink); background: var(--ink); color: #fff; }
.signal-grid { display: grid; grid-template-columns: repeat(4, 1fr); }
.signal-item { padding: 18px 24px; border-right: 1px solid #4b4b50; text-align: center; }
.signal-item:last-child { border-right: 0; }
.signal-item strong { display: block; color: var(--mint); font-size: 20px; }

.section { padding-block: 88px; }
.section-alt { border-block: 2px solid var(--ink); background: var(--white); }
.section-head { display: flex; align-items: end; justify-content: space-between; gap: 24px; margin-bottom: 34px; }
.section-head h2 { margin-bottom: 0; }
.section-index { font-size: 14px; font-weight: 900; color: var(--coral); }

.feature-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.feature-card {
  min-height: 260px;
  padding: 24px;
  border: 2px solid var(--ink);
  border-radius: 8px;
  background: var(--white);
  box-shadow: 5px 5px 0 var(--ink);
}
.feature-card:nth-child(2) { background: var(--sky); }
.feature-card:nth-child(3) { background: #edffe6; }
.feature-card:nth-child(4) { background: #fff4d4; }
.feature-no { width: 46px; height: 46px; display: grid; place-items: center; margin-bottom: 26px; border: 2px solid var(--ink); border-radius: 50%; background: var(--coral); color: #fff; font-weight: 900; }
.feature-card p, .path-card p, .quote p, .content-block p { margin: 0; color: #4b5155; }

.screens-wrap { position: relative; }
.screens {
  display: grid;
  grid-template-columns: repeat(5, minmax(180px, 1fr));
  gap: 22px;
  overflow-x: auto;
  padding: 10px 8px 26px;
  scrollbar-color: var(--coral) #e9ecef;
}
.screen-shot { margin: 0; min-width: 180px; }
.screen-shot img {
  width: 100%;
  max-width: 400px;
  height: auto;
  aspect-ratio: 9 / 16;
  object-fit: cover;
  border: 3px solid var(--ink);
  border-radius: 8px;
  background: #e9eff0;
  box-shadow: 6px 7px 0 var(--ink);
}
.screen-shot figcaption { margin-top: 14px; font-size: 14px; font-weight: 900; text-align: center; }

.path-grid { display: grid; grid-template-columns: 1.2fr .8fr .8fr; gap: 18px; }
.path-card { padding: 28px; border: 2px solid var(--ink); border-radius: 8px; background: var(--white); }
.path-card:first-child { background: var(--mint); }
.path-card:first-child p { color: #173e31; }
.path-card a { display: inline-block; margin-top: 18px; font-weight: 900; border-bottom: 2px solid; }

.quote-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.quote { margin: 0; padding: 26px; border-left: 6px solid var(--coral); background: var(--white); }
.quote p { font-size: 17px; }
.quote footer { margin-top: 16px; font-weight: 900; }

.faq-list { display: grid; gap: 12px; }
details { border: 2px solid var(--ink); border-radius: 6px; background: var(--white); }
summary { position: relative; padding: 18px 56px 18px 20px; cursor: pointer; font-weight: 900; list-style: none; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; position: absolute; right: 20px; top: 12px; font-size: 28px; color: var(--coral); }
details[open] summary::after { content: "−"; }
.detail-body { padding: 0 20px 20px; color: #4b5155; }
.detail-body p { margin: 0; }

.bottom-download { border-block: 2px solid var(--ink); background: var(--yellow); }
.bottom-download .container { min-height: 210px; display: flex; align-items: center; justify-content: space-between; gap: 30px; }
.bottom-download h2 { margin-bottom: 6px; }
.download-note { margin: 0; color: #4d431f; }

.site-footer { padding-block: 38px; background: var(--ink); color: #d5d7d8; }
.footer-grid { display: grid; grid-template-columns: .8fr 1.2fr; gap: 50px; align-items: start; }
.footer-brand .brand-name { color: #fff; }
.footer-brand img { background: #fff; }
.footer-links { display: flex; flex-wrap: wrap; gap: 18px; margin-top: 18px; }
.footer-links a { color: var(--mint); }
.disclaimer { margin: 0; font-size: 14px; }
.copyright { margin: 10px 0 0; font-size: 13px; color: #8e9397; }

.page-hero { border-bottom: 2px solid var(--ink); background: var(--sky); }
.page-hero .container { padding-block: 72px 62px; }
.page-hero h1 { max-width: 850px; margin-bottom: 16px; font-size: 62px; }
.page-lead { max-width: 820px; margin: 0; color: #3e464b; font-size: 18px; }
.crumbs { margin: 0 0 16px; font-size: 14px; font-weight: 800; }
.crumbs a { border-bottom: 1px solid; }

.article-layout { display: grid; grid-template-columns: 250px minmax(0, 1fr); gap: 48px; align-items: start; }
.side-nav { position: sticky; top: 100px; border: 2px solid var(--ink); background: var(--white); }
.side-nav strong { display: block; padding: 13px 16px; background: var(--ink); color: #fff; }
.side-nav a { display: block; padding: 11px 16px; border-top: 1px solid #d8dcdf; font-weight: 700; }
.side-nav a:hover { background: var(--yellow); }
.article { min-width: 0; }
.content-block { scroll-margin-top: 100px; padding-bottom: 52px; margin-bottom: 52px; border-bottom: 2px solid var(--ink); }
.content-block:last-child { border-bottom: 0; margin-bottom: 0; }
.content-block h2 { margin-bottom: 22px; }
.content-block h3 { margin-top: 30px; }
.content-block p + p { margin-top: 14px; }
.number-title { display: flex; align-items: center; gap: 14px; }
.number-title span { flex: 0 0 44px; width: 44px; height: 44px; display: grid; place-items: center; border: 2px solid var(--ink); border-radius: 50%; background: var(--mint); font-size: 17px; }
.check-list, .plain-list { margin: 20px 0 0; padding: 0; list-style: none; }
.check-list li, .plain-list li { position: relative; padding: 11px 0 11px 32px; border-bottom: 1px solid #dce2df; }
.check-list li::before { content: "✓"; position: absolute; left: 4px; color: var(--mint-dark); font-weight: 900; }
.plain-list { counter-reset: line; }
.plain-list li { padding-left: 42px; }
.plain-list li::before { counter-increment: line; content: counter(line, decimal-leading-zero); position: absolute; left: 0; font-weight: 900; color: var(--coral); }
.notice { margin-top: 22px; padding: 18px 20px; border: 2px solid var(--ink); border-left: 8px solid var(--yellow); background: #fff; }
.notice strong { display: block; }
.inline-link { color: var(--mint-dark); font-weight: 900; border-bottom: 2px solid; }

.feature-detail-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; margin-top: 24px; }
.feature-detail { padding: 24px; border: 2px solid var(--ink); background: var(--white); border-radius: 6px; }
.feature-detail:nth-child(3n+1) { border-top: 8px solid var(--mint); }
.feature-detail:nth-child(3n+2) { border-top: 8px solid var(--coral); }
.feature-detail:nth-child(3n+3) { border-top: 8px solid var(--yellow); }
.feature-detail p { margin: 0; }

.qa-group { display: grid; gap: 12px; }
.qa-group .detail-body a { color: var(--mint-dark); font-weight: 900; border-bottom: 1px solid; }
.related-band { padding: 30px; border: 2px solid var(--ink); background: var(--sky); }
.related-band h2 { margin-bottom: 14px; font-size: 28px; }
.related-links { display: flex; flex-wrap: wrap; gap: 12px; }
.related-links a { padding: 8px 12px; border: 2px solid var(--ink); background: #fff; font-weight: 800; }

@media (max-width: 980px) {
  .hero-grid { grid-template-columns: 1fr 400px; gap: 20px; }
  h1 { font-size: 58px; }
  h2 { font-size: 36px; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .screens { grid-template-columns: repeat(5, 210px); }
  .path-grid { grid-template-columns: 1fr 1fr; }
  .path-card:first-child { grid-column: 1 / -1; }
  .article-layout { grid-template-columns: 1fr; }
  .side-nav { position: static; display: flex; overflow-x: auto; }
  .side-nav strong, .side-nav a { flex: 0 0 auto; border-top: 0; border-right: 1px solid #d8dcdf; }
}

@media (max-width: 760px) {
  .container { width: min(calc(100% - 28px), var(--max)); }
  .nav-wrap { min-height: 68px; }
  .menu-toggle { display: grid; place-items: center; }
  .nav-links {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 68px;
    padding: 12px 14px 18px;
    border-bottom: 2px solid var(--ink);
    background: var(--paper);
    flex-direction: column;
    align-items: stretch;
  }
  .nav-links.open { display: flex; }
  .nav-links a { text-align: center; }
  .nav-links .button { box-shadow: none; }
  .hero { background: var(--sky); }
  .hero-grid { min-height: auto; grid-template-columns: 1fr; padding-block: 48px; }
  h1 { font-size: 44px; }
  h2 { font-size: 32px; }
  .phone-stage { min-height: 430px; width: min(100%, 430px); margin: 10px auto 0; }
  .phone { width: 54%; }
  .phone-main { left: 5%; }
  .burst { right: 2%; width: 100px; }
  .signal-grid { grid-template-columns: repeat(2, 1fr); }
  .signal-item:nth-child(2) { border-right: 0; }
  .signal-item:nth-child(-n+2) { border-bottom: 1px solid #4b4b50; }
  .section { padding-block: 64px; }
  .section-head { align-items: start; flex-direction: column; }
  .feature-grid, .quote-grid, .feature-detail-grid { grid-template-columns: 1fr; }
  .feature-card { min-height: auto; }
  .path-grid { grid-template-columns: 1fr; }
  .path-card:first-child { grid-column: auto; }
  .bottom-download .container { min-height: 260px; align-items: flex-start; justify-content: center; flex-direction: column; }
  .footer-grid { grid-template-columns: 1fr; gap: 26px; }
  .page-hero .container { padding-block: 52px 46px; }
  .page-hero h1 { font-size: 40px; }
}

@media (max-width: 420px) {
  .brand-name { font-size: 18px; }
  .hero-actions { align-items: stretch; flex-direction: column; }
  .hero-actions .button { width: 100%; }
  .phone-stage { min-height: 360px; }
  .signal-item { padding: 14px 8px; font-size: 13px; }
  .signal-item strong { font-size: 17px; }
  .screens { grid-template-columns: repeat(5, 178px); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; }
}