/* xinfinite.tech — visual language borrowed from U.S. tax-form paperwork:
   black "Part" tabs, heavy and hairline rules, line codes in a condensed grotesk.
   One accent (ledger green) for the action; red only for the penalty figure. */

@font-face {
  font-family: "Archivo";
  src: url("/fonts/archivo-latin.woff2") format("woff2");
  font-weight: 400 800;
  font-stretch: 62% 125%;
  font-display: swap;
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F,
    U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

:root {
  --paper: #ffffff;
  --ink: #121417;
  --ink-2: #50565f;
  --hair: #d7dadd;
  --fill: #f3f4f2;
  --tab: #121417;
  --tab-ink: #ffffff;
  --accent: #0b6b43;
  --accent-hover: #095a38;
  --accent-ink: #ffffff;
  --alert: #b42318;
  --notice: #fff4d6;
  --notice-ink: #5c4300;
  --shadow: rgba(18, 20, 23, .14);
  --cn: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Noto Sans SC", "Noto Sans CJK SC", sans-serif;
  --num: "Archivo", "Helvetica Neue", Arial, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0f1113;
    --ink: #e8eaed;
    --ink-2: #a4aab2;
    --hair: #2b3036;
    --fill: #171a1e;
    --tab: #e8eaed;
    --tab-ink: #0f1113;
    --accent: #3fbf84;
    --accent-hover: #5fd49c;
    --accent-ink: #04140c;
    --alert: #ff7b6e;
    --notice: #3a2f12;
    --notice-ink: #f6dc93;
    --shadow: rgba(0, 0, 0, .5);
  }
}
:root[data-theme="dark"] {
  --paper: #0f1113; --ink: #e8eaed; --ink-2: #a4aab2; --hair: #2b3036; --fill: #171a1e;
  --tab: #e8eaed; --tab-ink: #0f1113; --accent: #3fbf84; --accent-hover: #5fd49c; --accent-ink: #04140c;
  --alert: #ff7b6e; --notice: #3a2f12; --notice-ink: #f6dc93; --shadow: rgba(0, 0, 0, .5);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--cn);
  font-size: 17px;
  line-height: 1.75;
}
a { color: var(--accent); text-underline-offset: 3px; }
a:focus-visible, .cta:focus-visible, button:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
p { margin: 0; }
.wrap { max-width: 1080px; margin-inline: auto; padding-inline: 20px; }
.nobr { white-space: nowrap; }
.fig { font-family: var(--num); font-stretch: 72%; font-weight: 800; font-variant-numeric: tabular-nums; }

/* ---------- masthead ---------- */
.masthead { border-top: 6px solid var(--ink); }
.masthead .wrap { display: flex; align-items: center; justify-content: space-between; gap: 12px 20px;
  flex-wrap: wrap; padding-block: 14px; border-bottom: 1px solid var(--ink); }
.brand { font-family: var(--num); font-stretch: 78%; font-weight: 800; font-size: 17px; letter-spacing: .1em;
  text-transform: uppercase; color: var(--ink); text-decoration: none; }
.masthead nav { display: flex; gap: 18px; flex-wrap: wrap; font-size: 14px; }
.masthead nav a { color: var(--ink-2); text-decoration: none; }
.masthead nav a:hover { color: var(--ink); }

/* ---------- hero ---------- */
.hero { padding-block: 40px 56px; }
.eyebrow { font-family: var(--num); font-stretch: 78%; font-weight: 700; font-size: 13px; letter-spacing: .14em;
  text-transform: uppercase; color: var(--ink-2); }
.hero h1 { margin: 14px 0 0; font-size: clamp(38px, 7.4vw, 64px); line-height: 1.12; font-weight: 800;
  letter-spacing: -.01em; text-wrap: balance; }
.hero-grid { display: grid; grid-template-columns: 1fr; gap: 40px; margin-top: 28px; }
.lead { font-size: 19px; line-height: 1.7; color: var(--ink-2); max-width: 32em; }
.facts { margin: 28px 0 0; border-top: 2px solid var(--ink); }
.facts div { display: grid; grid-template-columns: 5.5em 1fr; gap: 16px; padding-block: 11px;
  border-bottom: 1px solid var(--hair); font-size: 15px; line-height: 1.6; }
.facts dt { color: var(--ink-2); }
.facts dd { margin: 0; }
.buy { margin-top: 28px; display: grid; gap: 14px; }
.price { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.price .fig { font-size: 60px; line-height: .9; }
.price .fig small { font-size: .42em; font-weight: 700; margin-right: 2px; }
.price span:last-child { font-size: 15px; color: var(--ink-2); }
.cta { display: flex; align-items: center; justify-content: center; gap: 12px; padding: 17px 24px;
  background: var(--accent); color: var(--accent-ink); font-size: 17px; font-weight: 700; text-decoration: none;
  border: 0; border-radius: 2px; cursor: pointer; font-family: inherit; }
.cta:hover { background: var(--accent-hover); }
.cta .arrow { font-family: var(--num); font-weight: 700; }
.cta[aria-disabled="true"] { background: transparent; color: var(--ink-2); border: 1.5px dashed var(--ink-2);
  cursor: default; }
.cta.secondary { background: transparent; color: var(--ink); border: 1.5px solid var(--ink); }
.cta.secondary:hover { background: var(--fill); }
.buy-note { font-size: 14px; line-height: 1.65; color: var(--ink-2); }
.buy-note li { margin: 2px 0; }
.buy-note ul { margin: 0; padding-left: 1.1em; }

.previews { margin: 0; }
.stack { position: relative; aspect-ratio: 1 / 1.22; max-width: 100%; }
.stack img { position: absolute; width: 64%; height: auto; display: block; background: #fff;
  border: 1px solid var(--hair); box-shadow: 0 1px 2px var(--shadow), 0 18px 40px -12px var(--shadow); }
.stack .back { left: 0; top: 0; }
.stack .front { right: 0; bottom: 0; }
.previews figcaption { margin-top: 12px; font-size: 13px; color: var(--ink-2); }

/* ---------- parts (sections) ---------- */
.part { display: grid; grid-template-columns: 1fr; gap: 18px 48px; padding-block: 44px; border-top: 2px solid var(--ink); }
.part h2 { margin: 0; align-self: start; line-height: 1.3; }
.tab { display: inline-block; background: var(--tab); color: var(--tab-ink); font-size: 16px; font-weight: 700;
  padding: 6px 12px 5px; }
.part-body { min-width: 0; display: grid; gap: 18px; }
.part-body > p { max-width: 38em; }
.muted { color: var(--ink-2); }
.small { font-size: 14px; color: var(--ink-2); }

/* schedule: what is due, when */
.sched { border-top: 1px solid var(--ink); }
.sched .row { display: grid; grid-template-columns: 4.6em 1fr; gap: 4px 18px; padding-block: 16px;
  border-bottom: 1px solid var(--hair); align-items: baseline; }
.when { grid-row: span 2; font-size: 34px; line-height: 1; }
.when.cn { font-family: var(--cn); font-stretch: normal; font-size: 19px; font-weight: 800; line-height: 1.5; }
.what { font-size: 18px; font-weight: 700; line-height: 1.5; }
.what small { display: block; font-size: 15px; font-weight: 400; color: var(--ink-2); line-height: 1.6; }
.risk { font-size: 15px; color: var(--ink-2); line-height: 1.6; }
.risk .fig { font-size: 18px; color: var(--alert); font-weight: 800; }

/* files in the package */
.files { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--ink); }
.files li { display: grid; grid-template-columns: 4.4em 1fr auto; gap: 4px 16px; align-items: baseline;
  padding-block: 12px; border-bottom: 1px solid var(--hair); }
.chip { font-family: var(--num); font-stretch: 78%; font-weight: 700; font-size: 12px; letter-spacing: .08em;
  border: 1.5px solid var(--ink); padding: 0 6px; text-align: center; line-height: 1.7; }
.files b { font-weight: 700; }
.files small { display: block; font-size: 14px; color: var(--ink-2); line-height: 1.55; }
.files .meta { font-family: var(--num); font-stretch: 85%; font-weight: 600; font-size: 15px; color: var(--ink-2);
  white-space: nowrap; font-variant-numeric: tabular-nums; }

/* chapters */
.toc { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: 1fr; column-gap: 40px;
  border-top: 1px solid var(--ink); }
.toc li { display: grid; grid-template-columns: 2.4em 1fr; gap: 10px; padding-block: 9px;
  border-bottom: 1px solid var(--hair); font-size: 16px; line-height: 1.55; }
.toc .fig { font-size: 17px; }

/* sources */
.sources { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--ink); }
.sources li { padding-block: 11px; border-bottom: 1px solid var(--hair); display: grid; gap: 2px; }
.doc { font-family: var(--num); font-stretch: 85%; font-weight: 700; font-size: 16px; letter-spacing: .01em; }
.sources span:last-child { font-size: 15px; color: var(--ink-2); }

/* who it is for */
.fit { display: grid; grid-template-columns: 1fr; gap: 28px; }
.fit h3 { margin: 0 0 8px; font-size: 16px; font-weight: 800; }
.checks { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--ink); }
.checks li { display: grid; grid-template-columns: 20px 1fr; gap: 12px; padding-block: 10px;
  border-bottom: 1px solid var(--hair); font-size: 16px; line-height: 1.6; }
.box { width: 18px; height: 18px; margin-top: .22em; border: 1.5px solid var(--ink); display: grid; place-items: center; }
.box svg { width: 12px; height: 12px; fill: none; stroke: var(--ink); stroke-width: 2.4; stroke-linecap: square; }

/* caution box, like the "Caution:" lines on a form */
.caution { position: relative; border: 1.5px solid var(--ink); padding: 22px 20px 16px; margin-top: 10px; }
.caution .label { position: absolute; top: -13px; left: 16px; background: var(--tab); color: var(--tab-ink);
  font-size: 14px; font-weight: 700; padding: 2px 10px; }
.caution ul { margin: 0; padding-left: 1.1em; }
.caution li { margin: 4px 0; }

/* steps: a real sequence */
.steps { list-style: none; margin: 0; padding: 0; counter-reset: step; border-top: 1px solid var(--ink); }
.steps li { display: grid; grid-template-columns: 2.4em 1fr; gap: 12px; padding-block: 14px;
  border-bottom: 1px solid var(--hair); }
.steps li::before { counter-increment: step; content: counter(step); font-family: var(--num); font-stretch: 72%;
  font-weight: 800; font-size: 28px; line-height: 1.05; }

/* questions */
.faq { display: grid; grid-template-columns: 1fr; column-gap: 40px; border-top: 1px solid var(--ink); }
.faq div { padding-block: 14px; border-bottom: 1px solid var(--hair); }
.faq h3 { margin: 0 0 4px; font-size: 17px; font-weight: 800; }
.faq p { color: var(--ink-2); font-size: 16px; }

/* english summary for reviewers */
.en { border: 1px solid var(--hair); padding: 20px 22px; display: grid; gap: 10px; font-size: 15px; line-height: 1.7; }
.en .eyebrow { font-size: 12px; }

.wechat { display: none; margin-top: 20px; padding: 12px 16px; background: var(--notice); color: var(--notice-ink);
  font-size: 15px; line-height: 1.6; }
.wechat.show { display: block; }

/* ---------- legal pages ---------- */
.doc-page { padding-block: 40px 56px; }
.doc-page .col { max-width: 720px; }
.doc-page h1 { margin: 12px 0 6px; font-size: clamp(30px, 5vw, 40px); line-height: 1.2; font-weight: 800; }
.doc-page .updated { font-size: 14px; color: var(--ink-2); margin-bottom: 20px; }
.doc-page h2 { margin: 30px 0 8px; padding-top: 12px; border-top: 1px solid var(--hair); font-size: 18px; font-weight: 800; }
.doc-page p, .doc-page li { font-size: 16px; line-height: 1.8; }
.doc-page p + p { margin-top: 10px; }
.doc-page ul { margin: 8px 0 0; padding-left: 1.2em; }
.doc-page .lang-en { margin-top: 56px; padding-top: 8px; border-top: 6px solid var(--ink); }

/* ---------- footer ---------- */
.foot { border-top: 6px solid var(--ink); margin-top: 8px; }
.foot .wrap { display: grid; grid-template-columns: 1fr; gap: 10px 48px; padding-block: 26px 48px; font-size: 14px;
  line-height: 1.7; color: var(--ink-2); }
.foot a { color: var(--ink-2); }
.foot .brand { font-size: 15px; }

/* ---------- wider screens ---------- */
@media (min-width: 640px) {
  .sched .row { grid-template-columns: 5em 1fr 12.5em; }
  .when { grid-row: auto; }
  .fit { grid-template-columns: 1fr 1fr; }
  .toc { grid-template-columns: 1fr 1fr; grid-auto-flow: column; grid-template-rows: repeat(5, auto); }
  .cta { justify-self: start; min-width: 300px; }
}
@media (min-width: 900px) {
  .hero-grid { grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr); gap: 64px; align-items: start; }
  .part { grid-template-columns: 190px minmax(0, 1fr); }
  .faq { grid-template-columns: 1fr 1fr; }
  .foot .wrap { grid-template-columns: 1.4fr 1fr; }
}
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto; } }

/* ---------- home: shelves of kits ---------- */
.shelf-head { display: flex; align-items: baseline; gap: 6px 14px; flex-wrap: wrap; padding-top: 36px; }
.shelf { display: grid; grid-template-columns: 1fr; gap: 36px 48px; padding-block: 8px 52px; }
.sheet { display: grid; grid-template-columns: 104px minmax(0, 1fr); gap: 18px; padding-top: 20px;
  border-top: 2px solid var(--ink); align-items: start; }
.sheet-cover img { display: block; width: 100%; height: auto; background: #fff; border: 1px solid var(--hair);
  box-shadow: 0 1px 2px var(--shadow), 0 12px 28px -12px var(--shadow); }
.sheet-body { min-width: 0; }
.sheet h2 { margin: 6px 0 8px; font-size: 22px; line-height: 1.35; font-weight: 800; }
.sheet h2 a { color: var(--ink); text-decoration: none; }
.sheet h2 a:hover { text-decoration: underline; }
.sheet p { color: var(--ink-2); font-size: 16px; line-height: 1.7; }
.sheet-facts { list-style: none; margin: 14px 0 0; padding: 0; border-top: 1px solid var(--hair); }
.sheet-facts li { padding-block: 7px; border-bottom: 1px solid var(--hair); font-size: 14px; color: var(--ink-2); }
.sheet-foot { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap;
  margin-top: 16px; }
.price-sm { font-size: 38px; line-height: 1; }
.price-sm small { font-size: .45em; font-weight: 700; margin-right: 2px; }
.sheet .cta { min-width: 0; padding: 12px 18px; font-size: 15px; }

/* ---------- download page ---------- */
.dl { display: grid; gap: 12px; margin-top: 26px; max-width: 560px; }
.dl h3 { margin: 14px 0 0; font-size: 16px; font-weight: 800; }
.dl h3:first-child { margin-top: 0; }

@media (min-width: 640px) {
  .toc.toc-6 { grid-template-rows: repeat(6, auto); }
  .sheet { grid-template-columns: 150px minmax(0, 1fr); gap: 24px; }
}
@media (min-width: 900px) {
  .shelf { grid-template-columns: 1fr 1fr; }
}