:root {
  --ink: #0f172a;
  --ink-soft: #334155;
  --sky: #0ea5e9;
  --sky-dark: #0284c7;
  --sky-pale: #e0f2fe;
  --line: #e2e8f0;
  --muted: #64748b;
  --page: #f8fafc;
  --surface: #ffffff;
  --yellow: #fbbf24;
  --radius: 18px;
  --shadow: 0 18px 45px rgb(15 23 42 / 10%);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 88px;
}

body {
  min-width: 320px;
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: Inter, "Segoe UI", "Microsoft YaHei", Arial, sans-serif;
  line-height: 1.65;
}

button,
a {
  font: inherit;
}

button {
  cursor: pointer;
}

a {
  color: inherit;
}

:focus-visible {
  outline: 3px solid rgb(14 165 233 / 52%);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  z-index: 60;
  top: 12px;
  left: 12px;
  transform: translateY(-160%);
  padding: 8px 12px;
  border-radius: 8px;
  background: var(--ink);
  color: #ffffff;
  text-decoration: none;
}

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

.site-header {
  position: sticky;
  z-index: 20;
  top: 0;
  display: flex;
  align-items: center;
  min-height: 72px;
  padding: 0 max(24px, calc((100vw - 1240px) / 2));
  border-bottom: 1px solid rgb(226 232 240 / 80%);
  background: rgb(255 255 255 / 92%);
  backdrop-filter: blur(16px);
}

.site-brand {
  display: flex;
  align-items: center;
  gap: 9px;
  color: var(--ink);
  font-size: 18px;
  font-weight: 800;
  text-decoration: none;
}

.site-brand span {
  color: var(--yellow);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 21px;
  margin-left: auto;
}

.site-nav a {
  color: var(--muted);
  font-size: 14px;
  font-weight: 650;
  text-decoration: none;
}

.site-nav a:hover,
.site-nav a.is-current {
  color: var(--sky-dark);
}

.menu-toggle {
  display: none;
  min-height: 40px;
  margin-left: auto;
  padding: 7px 11px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  color: var(--ink);
}

.section {
  width: min(1180px, calc(100% - 48px));
  margin: 0 auto;
  padding: 104px 0;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 0.88fr) minmax(520px, 1.12fr);
  align-items: center;
  gap: 58px;
  min-height: 650px;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--sky-dark);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.12em;
}

.hero h1,
h2 {
  letter-spacing: -0.035em;
  line-height: 1.16;
}

.hero h1 {
  max-width: 600px;
  margin: 0;
  font-size: clamp(39px, 5vw, 64px);
}

.hero-description {
  max-width: 550px;
  color: var(--muted);
  font-size: 18px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.official-channels {
  display: flex;
  align-items: center;
  gap: 14px;
  max-width: 410px;
  margin-top: 26px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface);
  box-shadow: 0 8px 20px rgb(15 23 42 / 5%);
}

.official-channel-copy {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 3px 12px;
  flex: 1;
  min-width: 0;
  font-size: 13px;
}

.official-channel-copy span {
  color: var(--muted);
}

.official-channel-copy a,
.official-channel-copy strong {
  overflow: hidden;
  color: var(--sky-dark);
  font-weight: 750;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.official-channel-copy a:hover {
  color: var(--sky);
}

.official-channels img {
  width: 86px;
  height: 86px;
  flex: 0 0 auto;
  border-radius: 8px;
  object-fit: cover;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 19px;
  border: 1px solid transparent;
  border-radius: 9px;
  font-weight: 750;
  text-decoration: none;
}

.button-primary {
  background: var(--sky);
  color: #ffffff;
  box-shadow: 0 10px 24px rgb(14 165 233 / 25%);
}

.button-primary:hover {
  background: var(--sky-dark);
}

.button-secondary {
  border-color: var(--line);
  background: #ffffff;
  color: var(--ink);
}

.guide-figure {
  min-width: 0;
  margin: 0;
}

.hero-figure {
  transform: perspective(1600px) rotateY(-3deg) rotateX(1deg);
}

.image-button {
  display: block;
  width: 100%;
  overflow: hidden;
  padding: 0;
  border: 1px solid #cbd5e1;
  border-radius: 14px;
  background: #ffffff;
  box-shadow: var(--shadow);
  text-align: left;
}

.image-button:hover img,
.image-button:focus-visible img {
  transform: scale(1.018);
}

.image-button:focus-visible {
  outline: 3px solid rgb(14 165 233 / 35%);
  outline-offset: 4px;
}

.image-button img {
  display: block;
  width: 100%;
  height: auto;
  transition: transform 0.25s ease;
}

.guide-figure figcaption {
  margin-top: 10px;
  color: var(--muted);
  font-size: 13px;
}

.section-heading {
  max-width: 690px;
  margin-bottom: 42px;
}

.section-heading h2,
.guide-copy h2 {
  margin: 0 0 14px;
  font-size: clamp(31px, 3.2vw, 46px);
}

.section-heading p:not(.eyebrow),
.guide-copy > p:not(.eyebrow) {
  color: var(--muted);
  font-size: 16px;
}

.quick-start {
  padding-top: 52px;
}

.step-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  padding: 0;
  list-style: none;
  counter-reset: step;
}

.step-grid li {
  position: relative;
  min-height: 170px;
  padding: 57px 20px 22px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface);
  box-shadow: 0 6px 15px rgb(15 23 42 / 4%);
}

.step-grid li::before {
  position: absolute;
  top: 18px;
  left: 20px;
  counter-increment: step;
  content: "0" counter(step);
  color: var(--sky);
  font-size: 21px;
  font-weight: 850;
}

.step-grid strong,
.step-grid span {
  display: block;
}

.step-grid span {
  margin-top: 7px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.55;
}

.guide-section {
  display: grid;
  grid-template-columns: minmax(0, 0.84fr) minmax(480px, 1.16fr);
  align-items: center;
  gap: 54px;
  border-top: 1px solid var(--line);
}

.guide-section.reverse {
  grid-template-columns: minmax(480px, 1.16fr) minmax(0, 0.84fr);
}

.guide-section.reverse .guide-copy {
  order: 2;
}

.guide-section.reverse .guide-figure {
  order: 1;
}

.guide-copy ol {
  padding-left: 22px;
}

.guide-copy li {
  margin: 11px 0;
  padding-left: 5px;
  color: var(--ink-soft);
}

.guide-note {
  margin-top: 22px;
  padding: 14px 16px;
  border: 1px solid #bae6fd;
  border-radius: 10px;
  background: #f0f9ff;
  color: #075985;
  font-size: 14px;
}

.faq-section {
  border-top: 1px solid var(--line);
}

.faq-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 13px;
}

.faq-grid details {
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: 11px;
  background: #ffffff;
}

.faq-grid summary {
  cursor: pointer;
  font-weight: 750;
}

.faq-grid p {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 26px max(24px, calc((100vw - 1180px) / 2));
  background: var(--ink);
  color: #cbd5e1;
  font-size: 13px;
}

.site-footer span:first-child {
  color: #ffffff;
  font-weight: 750;
}

.site-footer a {
  color: #e0f2fe;
}

.site-footer a:hover {
  color: #ffffff;
}

.image-preview[hidden] {
  display: none;
}

.image-preview {
  position: fixed;
  z-index: 50;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 28px;
}

.preview-backdrop {
  position: absolute;
  inset: 0;
  background: rgb(15 23 42 / 78%);
}

.preview-panel {
  position: relative;
  z-index: 1;
  width: min(1440px, 100%);
  max-height: calc(100vh - 56px);
  overflow: auto;
  border-radius: 12px;
  background: #ffffff;
  box-shadow: 0 30px 80px rgb(0 0 0 / 35%);
}

.preview-panel img {
  display: block;
  width: 100%;
  height: auto;
}

.preview-panel p {
  margin: 0;
  padding: 10px 50px 10px 16px;
  color: var(--muted);
  font-size: 13px;
}

.preview-close {
  position: absolute;
  z-index: 2;
  top: 10px;
  right: 10px;
  display: grid;
  width: 40px;
  height: 40px;
  place-items: center;
  border: 0;
  border-radius: 50%;
  background: rgb(15 23 42 / 84%);
  color: #ffffff;
  font-size: 25px;
  line-height: 1;
}

.preview-close:hover {
  background: var(--sky-dark);
}

.image-preview.is-open {
  display: grid;
}

@media (max-width: 800px) {
  html {
    scroll-padding-top: 76px;
  }

  .site-header {
    min-height: 62px;
    padding: 0 20px;
  }

  .menu-toggle {
    display: inline-flex;
    align-items: center;
  }

  .site-nav {
    position: absolute;
    top: 61px;
    right: 12px;
    left: 12px;
    display: none;
    align-items: stretch;
    gap: 0;
    padding: 8px;
    border: 1px solid var(--line);
    border-radius: 12px;
    background: #ffffff;
    box-shadow: var(--shadow);
  }

  .site-nav.is-open {
    display: grid;
  }

  .site-nav a {
    min-height: 44px;
    padding: 10px 12px;
  }

  .section {
    width: min(calc(100% - 32px), 620px);
    padding: 66px 0;
  }

  .hero,
  .guide-section,
  .guide-section.reverse {
    display: flex;
    flex-direction: column;
    gap: 30px;
    min-height: 0;
  }

  .hero {
    padding-top: 58px;
  }

  .official-channels {
    width: 100%;
  }

  .hero-figure {
    transform: none;
  }

  .guide-section.reverse .guide-copy,
  .guide-section.reverse .guide-figure {
    order: initial;
  }

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

  .step-grid li {
    min-height: 0;
  }

  .site-footer {
    flex-direction: column;
    padding: 24px 20px;
  }

  .image-preview {
    padding: 12px;
  }

  .preview-panel {
    max-height: calc(100vh - 24px);
  }

  .preview-panel img {
    min-width: 900px;
  }

  .guide-figure {
    width: 100%;
  }
}