* { box-sizing: border-box; }
  [hidden] { display: none !important; }
  html { --guide-header-height: 88px; color-scheme: dark; scroll-behavior: smooth; scroll-padding-top: calc(var(--guide-header-height) + 24px); }
  body { margin: 0; background: var(--bg-dark); color: var(--text-muted); font-family: "Inter", system-ui, sans-serif; font-size: 16px; line-height: 1.7; -webkit-font-smoothing: antialiased; }
  #app { position: fixed; inset: 0; z-index: 0; pointer-events: none; background: radial-gradient(at 0% 45%, var(--glow-orange), transparent 48%), radial-gradient(at 100% 55%, var(--glow-blue), transparent 48%); }
  .page { position: relative; z-index: 1; width: min(1120px, calc(100% - 64px)); margin: auto; padding-top: 20px; }
  a { color: var(--brand-blue-soft); text-underline-offset: .22em; }
  a:hover { color: var(--text-main); }
  a, button, summary { -webkit-tap-highlight-color: transparent; }
  :focus-visible { outline: 2px solid var(--brand-blue); outline-offset: 4px; box-shadow: var(--focus-ring); }
  .skip { position: absolute; inset-inline-start: 0; top: -100px; padding: 12px; background: var(--bg-dark); z-index: 6; }
  .skip:focus { top: 12px; }
  h1, h2, h3, p { margin: 0; }
  h1, h2, h3, strong, b { color: var(--text-main); }
  h1 { font-size: clamp(44px, 5.6vw, 76px); font-weight: 800; letter-spacing: -.055em; line-height: 1.04; }
  h2 { font-size: clamp(29px, 3.1vw, 42px); font-weight: 700; letter-spacing: -.04em; line-height: 1.15; }
  h3 { font-size: 19px; letter-spacing: -.025em; line-height: 1.35; }
  .eyebrow { font-family: var(--font-mono); font-size: 11px; font-weight: 600; line-height: 1.6; letter-spacing: .16em; text-transform: uppercase; color: var(--brand-blue); }
  .small { font-size: 13px; line-height: 1.7; }
  .stack { display: flex; flex-direction: column; gap: 16px; }
  .glass { background: var(--bg-panel); border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--glass-shadow); }
  .masthead { position: sticky; top: 12px; z-index: 5; direction: ltr; display: flex; justify-content: space-between; align-items: center; gap: 24px; padding: 14px 18px; background: var(--bg-panel); border: var(--border); border-radius: 22px; box-shadow: var(--glass-shadow); }
  .lockup { display: inline-flex; align-items: center; gap: 14px; text-decoration: none; flex-shrink: 0; }
  .brand-logo { width: 58px; height: 58px; object-fit: contain; }
  .wordmark { display: flex; flex-direction: column; gap: 7px; }
  .brand { font-size: 23px; font-weight: 700; line-height: 1; letter-spacing: .34em; margin-right: -.34em; color: var(--text-main); }
  .surface { display: flex; justify-content: space-between; width: 100%; font-family: var(--font-mono); font-size: 10px; line-height: 1; font-weight: 700; text-transform: uppercase; color: var(--brand-blue-soft); }
  .header-tools { display: flex; align-items: center; gap: 20px; min-width: 0; }
  .theme-button { padding: 9px 14px; border: var(--border-strong); background: transparent; border-radius: 12px; color: var(--text-main); cursor: pointer; font: 500 13px "Inter", sans-serif; min-height: 44px; }
  nav { display: flex; flex-wrap: wrap; align-items: center; gap: 14px 28px; padding: 20px 0; font-size: 13px; }
  nav a { text-decoration: none; }
  .hero { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); gap: 70px; align-items: center; padding: 58px 0 68px; }
  .hero-copy { display: flex; flex-direction: column; align-items: flex-start; gap: 26px; }
  .hero h1 span { color: var(--brand-blue); }
  .hero-intro { max-width: 51ch; font-size: 17px; }
  .actions { display: flex; flex-wrap: wrap; align-items: center; gap: 16px 24px; }
  .button { display: inline-flex; justify-content: center; align-items: center; gap: 12px; min-height: 48px; padding: 13px 20px; border-radius: 12px; border: var(--border-strong); font-weight: 600; font-size: 14px; text-decoration: none; color: var(--text-main); transition: transform 160ms ease; }
  .button:hover { transform: translateY(-1px); }
  .button.primary { border: 0; background: linear-gradient(115deg, var(--brand-blue), var(--brand-blue-soft)); color: var(--text-on-accent); }
  .text-link { font-size: 14px; }
  .example { padding: 28px; display: flex; flex-direction: column; gap: 24px; }
  .exchange { display: flex; flex-direction: column; gap: 10px; }
  .exchange + .exchange { border-top: var(--border); padding-top: 22px; }
  .exchange .eyebrow { color: var(--text-muted); font-size: 10px; }
  .exchange blockquote { margin: 0; color: var(--text-main); font-size: 20px; line-height: 1.5; letter-spacing: -.02em; }
  .exchange p { font-size: 15px; }
  .example-foot { padding-top: 16px; border-top: var(--border); font-size: 12px; font-family: var(--font-mono); }
  .section { padding: 62px 0; border-top: var(--border); display: flex; flex-direction: column; gap: 30px; }
  .section-head { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: end; }
  .section-head .stack { gap: 12px; }
  .section-head p { max-width: 53ch; }
  .grid { display: grid; gap: 18px; }
  .grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .card { padding: 27px; display: flex; flex-direction: column; gap: 15px; }
  .card .eyebrow { font-size: 10px; }
  .card p { font-size: 15px; }
  .callout { border-inline-start: 2px solid var(--brand-blue); padding-block: 4px; padding-inline-start: 20px; max-width: 80ch; }
  .callout strong { display: block; margin-bottom: 4px; }
  .steps { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 0; counter-reset: step; }
  .steps > li { counter-increment: step; display: grid; grid-template-columns: 45px 1fr; gap: 20px; padding: 23px 0; border-bottom: var(--border); }
  .steps > li:first-child { padding-top: 0; }
  .steps > li:last-child { border-bottom: 0; padding-bottom: 0; }
  .steps > li::before { content: counter(step, decimal-leading-zero); font-family: var(--font-mono); color: var(--brand-blue); font-size: 15px; line-height: 28px; }
  .steps h3 { margin-bottom: 8px; }
  .steps p { max-width: 70ch; }
  .split { display: grid; grid-template-columns: 1.28fr 1fr; gap: 50px; align-items: start; }
  .side-note { padding: 25px; display: flex; flex-direction: column; gap: 18px; }
  .side-note h3 { font-size: 17px; }
  .side-note p, .side-note li { font-size: 14px; }
  .side-note ul { margin: 0; padding-inline-start: 18px; display: flex; flex-direction: column; gap: 10px; }
  code { font-family: var(--font-mono); font-size: .87em; color: var(--brand-blue-soft); overflow-wrap: anywhere; }
  .path { font-size: 13px; color: var(--brand-blue-soft); font-family: var(--font-mono); overflow-wrap: anywhere; }
  .prompt { margin: 0; color: var(--text-main); font-size: 16px; line-height: 1.6; }
  .prompt-hint { font-family: var(--font-mono); font-size: 11px; letter-spacing: .04em; color: var(--text-muted); }
  .plan { padding: 28px; display: flex; flex-direction: column; gap: 17px; }
  .plan h3 { font-size: 25px; }
  .plan p { font-size: 14px; }
  .plan ul { margin: 0; padding: 0; list-style: none; display: flex; flex-direction: column; gap: 12px; font-size: 14px; }
  .plan li { padding-inline-start: 16px; position: relative; }
  .plan li::before { content: "·"; position: absolute; inset-inline-start: 0; color: var(--brand-blue); }
  .plan-foot { margin-top: auto; padding-top: 20px; border-top: var(--border); font-family: var(--font-mono); font-size: 11px; color: var(--brand-blue-soft); }
  .upgrade { display: flex; justify-content: space-between; align-items: center; gap: 28px; padding: 28px 0 0; border-top: var(--border); }
  .upgrade p { max-width: 73ch; font-size: 14px; }
  .upgrade .button { flex-shrink: 0; }
  details { border-bottom: var(--border); padding: 20px 0; }
  details:first-child { padding-top: 0; }
  details:last-child { border: 0; padding-bottom: 0; }
  summary { color: var(--text-main); font-size: 16px; font-weight: 600; cursor: pointer; padding: 3px 0; }
  details p { padding-block-start: 12px; padding-inline-start: 20px; max-width: 80ch; font-size: 14px; }
  .closing { padding: 48px 0 64px; display: flex; justify-content: space-between; gap: 30px; align-items: center; border-top: var(--border); }
  .closing h2 { font-size: 30px; }
  .closing .stack { gap: 12px; }
  .footer { padding: 22px 0 32px; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 18px; border-top: var(--border); font-size: 12px; }
  @media (max-width: 900px) {
    .hero { gap: 34px; grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr); }
    .section-head, .split { gap: 28px; }
    .grid.three { grid-template-columns: 1fr; }
    .plan { display: grid; grid-template-columns: .8fr 1.2fr; column-gap: 28px; }
    .plan ul { grid-column: 2; grid-row: 1 / 5; }
    .plan-foot { grid-column: 1; }
  }
  @media (max-width: 640px) {
    .page { width: calc(100% - 36px); }
    .masthead { padding: 12px 14px; }
    .brand-logo { width: 38px; height: 38px; }
    .wordmark, .header-tools .eyebrow { display: none; }
    nav { gap: 10px 20px; font-size: 12px; padding: 17px 0; }
    nav a { padding: 5px 0; }
    .hero { grid-template-columns: 1fr; gap: 32px; padding: 30px 0 44px; }
    .hero-copy { gap: 22px; }
    .hero-intro { font-size: 16px; }
    .hero h1 { font-size: clamp(39px, 10.5vw, 62px); }
    .hero .actions { width: 100%; }
    .example { padding: 24px; }
    .exchange blockquote { font-size: 19px; }
    .section { padding: 42px 0; gap: 26px; }
    .section-head, .split, .grid.two { grid-template-columns: 1fr; gap: 24px; }
    .section-head { gap: 18px; }
    .card, .plan { padding: 24px; }
    .plan { display: flex; }
    .steps > li { grid-template-columns: 30px 1fr; gap: 12px; padding: 22px 0; }
    .steps h3 { font-size: 17px; }
    .steps p { font-size: 15px; }
    .upgrade, .closing { flex-direction: column; align-items: flex-start; }
    .closing { padding: 38px 0 44px; }
  }
  @media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after { transition: none !important; animation: none !important; }
  }
  @media print {
    body { background: white; color: black; font-size: 10pt; }
    .masthead { position: static; background: transparent; border: 0; box-shadow: none; }
    #app, nav, .header-tools, .actions, .upgrade .button, .closing .button, .skip { display: none !important; }
    .page { width: 100%; }
    h1, h2, h3, strong, b, a, code, .eyebrow, .brand, .surface, .prompt, .path, .plan-foot { color: black !important; }
    h1 { font-size: 34pt; }
    h2 { font-size: 21pt; }
    .hero { padding: 28px 0; gap: 24px; }
    .section { padding: 24px 0; gap: 20px; }
    .glass { background: transparent; box-shadow: none; border: 1px solid silver; break-inside: avoid; }
    .grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .plan { display: flex; padding: 16px; }
    .card { padding: 16px; }
    .steps > li { break-inside: avoid; padding: 12px 0; }
    details { break-inside: avoid; }
    details p { display: block !important; }
    .footer a::after { content: " (" attr(href) ")"; }
  }
  
  .header-tools { flex-wrap: wrap; justify-content: flex-end; gap: 12px; }
  .language-field { display: flex; align-items: center; gap: 8px; }
  .language-select { max-width: 150px; min-height: 44px; padding: 8px; font: inherit; font-size: 13px; color: var(--text-main); background: var(--bg-dark); border: var(--border-strong); border-radius: 12px; }
  #language-status { font-size: 13px; margin-block: 12px; }
  main, .hero-copy, .section-head > *, .steps > li > div { min-width: 0; }
  h1, h2, h3, p, blockquote, li, a { overflow-wrap: anywhere; }
  code, bdi { unicode-bidi: isolate; }
  html[dir="rtl"] .header-tools { direction: rtl; }
  html[dir="rtl"] h1, html[dir="rtl"] h2, html[dir="rtl"] h3, html[dir="rtl"] .eyebrow { letter-spacing: normal; }
  html:lang(ar), html:lang(fa) { --guide-script: "Geeza Pro", "Noto Sans Arabic", Tahoma; }
  html:lang(he) { --guide-script: "Arial Hebrew", "Noto Sans Hebrew", Arial; }
  html:lang(zh) { --guide-script: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC"; }
  html:lang(ja) { --guide-script: "Hiragino Sans", "Yu Gothic", "Noto Sans CJK JP"; }
  html:lang(ko) { --guide-script: "Apple SD Gothic Neo", "Malgun Gothic", "Noto Sans CJK KR"; }
  body { font-family: "Inter", var(--guide-script, system-ui), system-ui, sans-serif; }
  @media (max-width: 900px) { .header-tools > .eyebrow { display: none; } }
  @media (max-width: 640px) {
    .header-tools { gap: 8px; }
    .theme-button { padding-inline: 10px; }
    .masthead { gap: 12px; }
    .language-select { max-width: 122px; }
  }