:root {
  --paper: #ffffff;
  --ink: #101114;
  --muted: #60636b;
  --rule: #d9dbe0;
  --rule-strong: #aeb2bb;
  --v1: #1248c4;
  --v1-soft: #eef3ff;
  --v2: #e65212;
  --v2-soft: #fff2eb;
  --soft: #f6f7f9;
  --max: 1480px;
  --serif: Georgia, "Songti SC", "STSong", "Noto Serif CJK SC", serif;
  --sans: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
code { font-family: var(--mono); font-size: .92em; }

.scroll-progress {
  position: fixed; inset: 0 0 auto; height: 3px; z-index: 100;
  background: transparent;
}
.scroll-progress span { display: block; height: 100%; width: 0; background: var(--v1); }

.site-header {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  min-height: 68px; padding: 0 max(28px, calc((100vw - var(--max)) / 2));
  border-bottom: 1px solid var(--rule); background: rgba(255,255,255,.96); backdrop-filter: blur(12px);
}
.brand { display: flex; gap: 12px; align-items: center; text-decoration: none; font-weight: 750; letter-spacing: -.02em; }
.brand-mark { display: grid; place-items: center; width: 28px; height: 28px; border: 1px solid var(--ink); font-family: var(--serif); font-weight: 700; }
.site-header nav { display: flex; gap: 34px; }
.site-header nav a { padding: 22px 0 19px; border-bottom: 2px solid transparent; color: #31333a; text-decoration: none; font-size: 14px; font-weight: 650; }
.site-header nav a:hover, .site-header nav a:focus-visible { border-color: var(--v1); color: var(--v1); outline: none; }

.section-shell { width: min(var(--max), calc(100% - 56px)); margin: 0 auto; }
.hero { padding-top: clamp(24px, 2.5vw, 42px); }
.visit-counter {
  display: grid;
  grid-template-columns: minmax(300px, 1.25fr) repeat(4, minmax(118px, .42fr));
  margin-bottom: clamp(34px, 3.5vw, 56px);
  border-top: 1px solid var(--ink);
  border-bottom: 1px solid var(--ink);
}
.visit-counter-intro {
  display: flex;
  justify-content: space-between;
  gap: 22px;
  align-items: center;
  min-height: 88px;
  padding: 16px 24px 16px 0;
}
.visit-counter-intro h2 {
  margin-bottom: 3px;
  font-family: var(--serif);
  font-size: 22px;
  letter-spacing: -.025em;
}
.visit-counter-intro p { margin: 0; color: var(--muted); font-size: 12px; }
.visit-counter-intro > span {
  flex: 0 0 auto;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 11px;
}
.visit-counter-intro > span::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  margin-right: 7px;
  border-radius: 50%;
  background: var(--rule-strong);
  vertical-align: 1px;
}
.visit-counter-intro > span.is-ready::before { background: #16834a; }
.visit-counter-intro > span.is-error::before { background: var(--v2); }
.counter-metric {
  display: grid;
  place-content: center;
  min-height: 88px;
  padding: 12px 18px;
  border-left: 1px solid var(--rule);
  text-align: center;
}
.counter-metric strong {
  font-family: var(--serif);
  font-size: clamp(28px, 2.5vw, 40px);
  font-variant-numeric: tabular-nums;
  line-height: 1;
}
.counter-metric span { margin-top: 7px; color: var(--muted); font-size: 11px; letter-spacing: .08em; }
.counter-metric-v1 strong { color: var(--v1); }
.counter-metric-v2 strong { color: var(--v2); }
.counter-metric-duration strong { font-size: clamp(21px, 2vw, 32px); }
.hero-copy { max-width: 1540px; margin: 0 auto 38px; text-align: center; }
h1, h2, h3, p { margin-top: 0; }
.hero h1 { margin-bottom: 18px; font-family: var(--serif); font-size: clamp(46px, 4vw, 78px); line-height: 1.04; letter-spacing: -.055em; font-weight: 700; white-space: nowrap; }
.hero h1 span { color: var(--v1); font-style: normal; }
.hero h1 em { color: var(--v2); font-style: normal; }
.hero-summary { max-width: 940px; margin: 0 auto 18px; color: #3d4048; font-size: clamp(17px, 1.3vw, 21px); line-height: 1.55; }
.authorship-note { display: inline-flex; gap: 18px; align-items: baseline; padding: 12px 0; border-top: 1px solid var(--rule-strong); border-bottom: 1px solid var(--rule-strong); text-align: left; font-size: 14px; }
.authorship-note strong { white-space: nowrap; }
.authorship-note span { color: var(--muted); }

.evolution-board { display: grid; grid-template-columns: minmax(0, 1fr) 120px minmax(0, 1fr); align-items: stretch; border-top: 1px solid var(--ink); border-bottom: 1px solid var(--ink); }
.version-panel { padding: 30px 30px 32px; }
.version-panel header { border-bottom: 2px solid; margin-bottom: 20px; }
.version-panel header p { margin-bottom: 6px; font-family: var(--mono); font-size: 13px; letter-spacing: .02em; text-transform: uppercase; }
.version-panel h2 { margin-bottom: 14px; font-family: var(--serif); font-size: clamp(27px, 2.1vw, 36px); line-height: 1.18; letter-spacing: -.035em; }
.version-panel-v1 header { color: var(--v1); }
.version-panel-v2 header { color: var(--v2); }
.flow { display: flex; align-items: center; gap: 12px; margin: 22px 0; }
.flow span { flex: 1; min-height: 70px; display: grid; place-content: center; border: 1px solid var(--v1); color: var(--v1); text-align: center; font-family: var(--mono); font-size: 15px; }
.flow small { display: block; color: var(--muted); font-family: var(--sans); font-size: 12px; }
.flow b { font-weight: 500; }
.layer-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; margin: 22px 0; }
.layer-grid span { padding: 12px 10px; border: 1px solid var(--v2); color: #a83100; text-align: center; font-size: 14px; font-weight: 650; }
.version-panel ul { margin: 20px 0 0; padding-left: 1.1em; color: #383b42; }
.evolution-spine { display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 10px; border-left: 1px solid var(--rule); border-right: 1px solid var(--rule); font-family: var(--serif); }
.evolution-spine i { height: 36px; width: 1px; background: var(--rule-strong); }
.evolution-spine span { color: var(--muted); font-size: 12px; }
.evolution-spine strong { writing-mode: vertical-rl; letter-spacing: .2em; font-size: 17px; }
.thesis-strip { display: grid; grid-template-columns: 170px 1fr; gap: 40px; align-items: baseline; padding: 20px 0 26px; border-bottom: 1px solid var(--rule); }
.thesis-strip p { margin: 0; color: var(--muted); font-family: var(--mono); font-size: 13px; }
.thesis-strip strong { font-family: var(--serif); font-size: clamp(20px, 2vw, 30px); line-height: 1.45; }

.principles { padding: 120px 0 110px; }
.section-heading { display: flex; justify-content: space-between; gap: 32px; align-items: end; margin-bottom: 48px; }
.section-heading h2 { margin-bottom: 12px; font-family: var(--serif); font-size: clamp(38px, 4.2vw, 68px); line-height: 1.08; letter-spacing: -.045em; }
.section-heading p { margin-bottom: 0; color: var(--muted); font-size: 17px; }
.focus-control { display: flex; border: 1px solid var(--rule-strong); }
.focus-control button { border: 0; border-right: 1px solid var(--rule-strong); background: #fff; padding: 10px 18px; color: #555861; cursor: pointer; font-size: 13px; }
.focus-control button:last-child { border-right: 0; }
.focus-control button.is-active { background: var(--ink); color: #fff; }
.principle-lines { border-top: 1px solid var(--ink); }
.principle-lines article { display: grid; grid-template-columns: 110px 1fr; padding: 34px 0; border-bottom: 1px solid var(--rule); transition: opacity .25s ease, transform .25s ease; }
.principle-lines article > span { color: var(--rule-strong); font-family: var(--serif); font-size: 36px; }
.principle-lines article div { display: grid; grid-template-columns: minmax(220px, 380px) minmax(0, 1fr); gap: 48px; }
.principle-lines h3 { margin-bottom: 0; font-family: var(--serif); font-size: 28px; }
.principle-lines p { margin-bottom: 0; color: #444750; }
body[data-focus="v1"] [data-version="v2"], body[data-focus="v2"] [data-version="v1"] { opacity: .2; transform: translateX(8px); }

.matrix-section { padding: 110px 0 120px; border-top: 1px solid var(--ink); border-bottom: 1px solid var(--ink); background: #fbfbfc; }
.matrix-heading { align-items: center; }
.difference-switch { display: flex; gap: 10px; align-items: center; color: #454851; cursor: pointer; font-size: 14px; white-space: nowrap; }
.difference-switch input { position: absolute; opacity: 0; pointer-events: none; }
.difference-switch span { position: relative; display: inline-block; width: 42px; height: 22px; border: 1px solid var(--rule-strong); background: #fff; }
.difference-switch span::after { content: ""; position: absolute; top: 3px; left: 3px; width: 14px; height: 14px; background: #91949b; transition: .2s ease; }
.difference-switch input:checked + span { border-color: var(--v2); }
.difference-switch input:checked + span::after { transform: translateX(20px); background: var(--v2); }
.difference-switch input:focus-visible + span { outline: 2px solid var(--v1); outline-offset: 3px; }
.category-rail { display: flex; gap: 0; overflow-x: auto; border-bottom: 1px solid var(--rule-strong); margin-bottom: 0; }
.category-rail button { min-width: 110px; border: 0; border-bottom: 3px solid transparent; background: transparent; padding: 14px 22px 12px; color: #42454d; cursor: pointer; font-size: 14px; }
.category-rail button.is-active { border-color: var(--v1); color: var(--v1); font-weight: 700; }
.comparison-table { background: #fff; }
.comparison-head, .comparison-row-main { display: grid; grid-template-columns: 150px minmax(210px, 1.1fr) 170px minmax(240px, 1.15fr) minmax(220px, 1fr); }
.comparison-head { border-bottom: 1px solid var(--ink); color: #4f525a; font-size: 12px; font-weight: 700; letter-spacing: .04em; }
.comparison-head span { padding: 18px 16px; }
.comparison-head span:nth-child(2) { color: var(--v1); }
.comparison-head span:nth-child(4) { color: var(--v2); }
.comparison-row { border-bottom: 1px solid var(--rule); }
.comparison-row[hidden] { display: none; }
.comparison-row-main { width: 100%; border: 0; background: transparent; padding: 0; color: inherit; text-align: left; cursor: pointer; }
.comparison-row-main:hover { background: #f8f9fb; }
.comparison-row-main:focus-visible { outline: 2px solid var(--v1); outline-offset: -2px; }
.comparison-row-main > span { min-height: 96px; padding: 20px 16px; border-right: 1px solid #eceef1; }
.comparison-row-main > span:last-child { border-right: 0; }
.dimension-cell { position: relative; display: flex; gap: 10px; align-items: flex-start; font-weight: 750; }
.dimension-cell::before { content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 3px; background: var(--v1); }
.comparison-row[data-change="new"] .dimension-cell::before { background: var(--v2); }
.dimension-cell i { margin-top: 2px; font-style: normal; color: var(--muted); transition: transform .2s ease; }
.comparison-row.is-open .dimension-cell i { transform: rotate(90deg); }
.dimension-cell small { display: block; margin-top: 5px; color: var(--muted); font-size: 11px; font-weight: 500; }
.v1-cell { color: #242c43; }
.v2-cell strong { display: block; color: var(--v2); }
.delta-cell { display: grid; place-content: center start; color: #25272d; font-family: var(--serif); font-size: 17px; }
.impact-cell { color: #373a42; }
.comparison-detail { display: none; grid-template-columns: 150px 1fr 1fr; gap: 30px; padding: 24px 30px 30px 166px; border-top: 1px dashed var(--rule); background: #fafafb; }
.comparison-row.is-open .comparison-detail { display: grid; }
.comparison-detail strong { font-size: 13px; }
.comparison-detail p { margin-bottom: 0; color: #4d5059; font-size: 14px; }
.comparison-detail .detail-verdict { padding-left: 20px; border-left: 2px solid var(--v2); }
.table-instruction { margin: 18px 0 0; color: var(--muted); font-size: 12px; }

.tension { padding: 120px 0; }
.tension-list { border-top: 1px solid var(--ink); }
.tension-list article { display: grid; grid-template-columns: 130px minmax(280px, 1fr) minmax(0, 1.3fr); gap: 50px; padding: 36px 0; border-bottom: 1px solid var(--rule); }
.tension-list span { color: var(--v2); font-family: var(--mono); font-size: 13px; }
.tension-list h3 { margin-bottom: 0; font-family: var(--serif); font-size: 27px; line-height: 1.35; }
.tension-list p { margin-bottom: 0; color: #4d5058; }

.judgement { padding: 118px 0 124px; border-top: 1px solid var(--ink); border-bottom: 1px solid var(--ink); background: #fff; color: var(--ink); }
.judgement-intro { display: grid; grid-template-columns: 1.05fr 1fr; gap: 90px; align-items: end; margin-bottom: 80px; }
.judgement h2 { margin-bottom: 0; font-family: var(--serif); font-size: clamp(42px, 5vw, 76px); line-height: 1.12; letter-spacing: -.045em; }
.judgement-intro p { margin-bottom: 6px; color: var(--muted); font-size: 18px; }
.roadmap { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; border-top: 1px solid var(--rule-strong); border-bottom: 1px solid var(--rule-strong); background: var(--rule); }
.roadmap-stage { display: grid; grid-template-columns: 44px 1fr; column-gap: 16px; border: 0; background: #fff; color: var(--ink); padding: 28px 24px; text-align: left; cursor: pointer; }
.roadmap-stage span { grid-row: 1 / span 2; display: grid; place-items: center; width: 38px; height: 38px; border: 1px solid currentColor; border-radius: 50%; font-family: var(--serif); }
.roadmap-stage strong { font-family: var(--serif); font-size: 23px; }
.roadmap-stage small { color: var(--muted); }
.roadmap-stage.is-active { background: var(--soft); color: var(--ink); }
.roadmap-stage.is-active small { color: var(--muted); }
.stage-now.is-active span { background: var(--v1); border-color: var(--v1); color: #fff; }
.stage-later.is-active span { background: var(--v2); border-color: var(--v2); color: #fff; }
.stage-no.is-active span { background: var(--ink); color: #fff; }
.decision-table { margin: 34px 0 60px; border-top: 1px solid var(--rule-strong); }
.decision-head, .decision-row { display: grid; grid-template-columns: 1fr 1.7fr 1.55fr 150px; }
.decision-head { color: var(--muted); font-size: 11px; font-weight: 700; letter-spacing: .08em; }
.decision-head span, .decision-row span { padding: 14px 14px; border-bottom: 1px solid var(--rule); }
.decision-row { color: #40434b; font-size: 14px; }
.decision-row span:first-child { color: var(--ink); font-weight: 700; }
.decision-row .decision-status { font-family: var(--mono); color: var(--ink); }
.architecture-recommendation { border: 1px solid var(--rule-strong); padding: 30px; }
.architecture-recommendation h3 { margin-bottom: 28px; font-family: var(--serif); font-size: 28px; }
.architecture-flow { display: flex; gap: 20px; align-items: center; }
.architecture-flow span { flex: 1; }
.architecture-flow strong { display: block; font-size: 15px; }
.architecture-flow small { color: var(--muted); }
.architecture-flow b { color: var(--rule-strong); font-weight: 400; }

.verdict { padding: 120px 0 126px; text-align: center; }
.verdict > p:first-child { color: var(--v2); font-family: var(--mono); font-size: 13px; }
.verdict h2 { margin-bottom: 32px; font-family: var(--serif); font-size: clamp(46px, 6vw, 86px); line-height: 1.1; letter-spacing: -.05em; }
.verdict > p:last-child { max-width: 930px; margin: 0 auto; color: #41444c; font-size: 19px; }

footer { display: grid; grid-template-columns: .7fr 1.3fr; gap: 80px; padding: 68px max(28px, calc((100vw - var(--max)) / 2)); border-top: 1px solid var(--ink); background: #f4f5f7; }
footer h2 { font-family: var(--serif); font-size: 32px; }
footer p { color: var(--muted); }
footer ol { margin: 0; padding: 0; list-style: none; }
footer li { display: grid; grid-template-columns: minmax(260px, .8fr) 1fr; gap: 24px; padding: 14px 0; border-bottom: 1px solid var(--rule); }
footer li a { font-weight: 750; text-underline-offset: 4px; }
footer li span { color: var(--muted); font-size: 14px; }
.footer-meta { grid-column: 1 / -1; margin: 0; padding-top: 12px; border-top: 1px solid var(--rule-strong); font-size: 12px; }

@media (max-width: 1120px) {
  .hero h1 { white-space: normal; }
  .evolution-board { grid-template-columns: 1fr 74px 1fr; }
  .version-panel { padding-inline: 20px; }
  .layer-grid { grid-template-columns: repeat(2, 1fr); }
  .comparison-head { display: none; }
  .comparison-row-main { grid-template-columns: 150px 1fr 1fr; }
  .comparison-row-main > span { min-height: auto; }
  .comparison-row-main .delta-cell { grid-column: 2 / -1; grid-row: 2; border-top: 1px dashed var(--rule); }
  .comparison-row-main .impact-cell { grid-column: 2 / -1; border-top: 1px dashed var(--rule); }
  .comparison-detail { padding-left: 166px; grid-template-columns: 1fr 1fr; }
  .comparison-detail > strong { display: none; }
  .tension-list article { grid-template-columns: 100px 1fr; }
  .tension-list p { grid-column: 2; }
}

@media (max-width: 820px) {
  .site-header { padding: 0 18px; }
  .site-header nav { gap: 18px; }
  .site-header nav a:last-child { display: none; }
  .section-shell { width: min(100% - 32px, var(--max)); }
  .hero { padding-top: 22px; }
  .visit-counter { grid-template-columns: repeat(2, 1fr); }
  .visit-counter-intro { grid-column: 1 / -1; padding-right: 0; border-bottom: 1px solid var(--rule); }
  .counter-metric:nth-child(even) { border-left: 0; }
  .counter-metric:nth-child(n+4) { border-top: 1px solid var(--rule); }
  .hero-copy { margin-bottom: 42px; }
  .authorship-note { display: block; }
  .authorship-note strong { display: block; margin-bottom: 4px; }
  .evolution-board { display: block; }
  .evolution-spine { min-height: 76px; flex-direction: row; border: 0; border-top: 1px solid var(--rule); border-bottom: 1px solid var(--rule); }
  .evolution-spine i { width: 32px; height: 1px; }
  .evolution-spine strong { writing-mode: horizontal-tb; }
  .thesis-strip { grid-template-columns: 1fr; gap: 8px; }
  .section-heading, .judgement-intro { display: block; }
  .section-heading > div:first-child { margin-bottom: 28px; }
  .focus-control { width: max-content; max-width: 100%; overflow-x: auto; }
  .principle-lines article { grid-template-columns: 58px 1fr; }
  .principle-lines article div { display: block; }
  .principle-lines h3 { margin-bottom: 8px; }
  .matrix-heading .difference-switch { margin-top: 26px; }
  .comparison-row-main { display: block; }
  .comparison-row-main > span { display: block; padding: 15px 18px 15px 136px; border-right: 0; border-bottom: 1px dashed #e5e7eb; position: relative; }
  .comparison-row-main > span::after { position: absolute; left: 18px; top: 15px; width: 100px; color: var(--muted); font-size: 11px; font-weight: 650; }
  .comparison-row-main .dimension-cell { padding-left: 18px; font-size: 18px; }
  .comparison-row-main .dimension-cell::after { display: none; }
  .comparison-row-main .v1-cell::after { content: "V1 原始方法"; color: var(--v1); }
  .comparison-row-main .delta-cell::after { content: "变化本质"; }
  .comparison-row-main .v2-cell::after { content: "V2 社区扩展"; color: var(--v2); }
  .comparison-row-main .impact-cell::after { content: "微信知识库"; }
  .comparison-detail { padding: 20px 18px; display: none; grid-template-columns: 1fr; }
  .comparison-row.is-open .comparison-detail { display: grid; }
  .tension-list article { display: block; }
  .tension-list span, .tension-list h3 { display: block; margin-bottom: 12px; }
  .judgement-intro p { margin-top: 28px; }
  .roadmap { grid-template-columns: 1fr; }
  .decision-head { display: none; }
  .decision-row { display: block; padding: 15px 0; border-bottom: 1px solid var(--rule); }
  .decision-row span { display: block; border: 0; padding: 4px 10px 4px 120px; position: relative; }
  .decision-row span::before { position: absolute; left: 10px; color: var(--muted); font-size: 11px; }
  .decision-row span:nth-child(1)::before { content: "机制"; }
  .decision-row span:nth-child(2)::before { content: "收益"; }
  .decision-row span:nth-child(3)::before { content: "风险"; }
  .decision-row span:nth-child(4)::before { content: "结论"; }
  .architecture-flow { display: grid; grid-template-columns: 1fr; }
  .architecture-flow b { transform: rotate(90deg); width: max-content; }
  footer { grid-template-columns: 1fr; gap: 30px; }
  footer li { grid-template-columns: 1fr; gap: 4px; }
  .footer-meta { grid-column: auto; }
}

@media (max-width: 520px) {
  body { font-size: 15px; }
  .site-header { min-height: 58px; }
  .brand span:last-child { display: none; }
  .site-header nav { gap: 14px; }
  .site-header nav a { font-size: 12px; padding-block: 18px 16px; }
  .hero h1 { font-size: 48px; }
  .visit-counter-intro { min-height: 74px; }
  .visit-counter-intro h2 { font-size: 19px; }
  .visit-counter-intro { display: block; padding-block: 13px; }
  .visit-counter-intro > span { display: block; margin-top: 7px; font-size: 10px; }
  .counter-metric { min-height: 76px; padding-inline: 7px; }
  .counter-metric strong { font-size: 27px; }
  .counter-metric-duration strong { font-size: 21px; }
  .counter-metric span { font-size: 9px; letter-spacing: .04em; }
  .hero-summary { font-size: 17px; }
  .version-panel { padding: 34px 14px 36px; }
  .flow { gap: 6px; }
  .flow span { min-width: 0; font-size: 11px; }
  .flow b { font-size: 11px; }
  .layer-grid { grid-template-columns: repeat(2, 1fr); }
  .principles, .tension, .verdict { padding-block: 84px; }
  .matrix-section, .judgement { padding-block: 84px; }
  .section-heading h2 { font-size: 42px; }
  .principle-lines article { grid-template-columns: 1fr; }
  .principle-lines article > span { font-size: 20px; }
  .category-rail button { min-width: 92px; padding-inline: 14px; }
  .comparison-row-main > span { padding-left: 118px; }
  .comparison-row-main > span::after { width: 84px; }
  .comparison-row-main .dimension-cell { padding-left: 15px; }
  .judgement h2 { font-size: 44px; }
  .architecture-recommendation { padding: 22px 18px; }
}

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