/* QuantStrategyLab organisation landing — restrained "Research Charter" identity.
   Tokens mirror .design/landing-approved; --ink3 is slightly darker/lighter than the
   mock so 12px metadata text meets WCAG AA (4.5:1) in both themes. */
:root {
  --serif: "Source Serif Pro", "Source Serif 4", "Noto Serif CJK SC", Georgia, "Times New Roman", serif;
  --sans: "Inter", "Noto Sans CJK SC", "Noto Sans SC", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "Source Code Pro", "Noto Sans Mono CJK SC", ui-monospace, SFMono-Regular, Menlo, monospace;
  --zh-serif: "Noto Serif CJK SC", "Source Han Serif SC", "Source Serif Pro", Georgia, serif;
  --zh-sans: "Noto Sans CJK SC", "Noto Sans SC", "Inter", system-ui, sans-serif;
}
[data-theme=light] {
  --bg: #F5F4EF;
  --surf: #FBFAF7;
  --ink: #15181D;
  --ink2: #474D56;
  --ink3: #5F6570;
  --rule: #D8D5CC;
  --rule2: #BDB9AE;
  --acc: #22483E;
  --acc2: #E3EAE5;
  --onacc: #F5F4EF;
}
[data-theme=dark] {
  --bg: #0F1215;
  --surf: #151A1E;
  --ink: #E6E4DE;
  --ink2: #A3A9B1;
  --ink3: #858C97;
  --rule: #262C33;
  --rule2: #363E46;
  --acc: #8EB8A8;
  --acc2: #18241F;
  --onacc: #0F1215;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
::-webkit-scrollbar { width: 0; }
html { background: var(--bg); }
body {
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.6 var(--sans);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
:lang(zh-CN) body { font-family: var(--zh-sans); line-height: 1.75; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
:focus-visible { outline: 2px solid var(--acc); outline-offset: 3px; }
.w { max-width: 1200px; margin: 0 auto; padding: 0 48px; }
.eyebrow {
  font: 500 12px/1 var(--mono);
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--ink3);
}
:lang(zh-CN) .eyebrow { letter-spacing: .12em; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* header */
header { border-bottom: 1px solid var(--rule); }
header .w { display: flex; align-items: center; height: 72px; gap: 40px; }
.mark {
  display: flex;
  align-items: center;
  gap: 12px;
  font: 600 17px/1 var(--serif);
  letter-spacing: -.005em;
}
.mark svg { width: 26px; height: 26px; flex: none; }
nav.links { display: flex; gap: 30px; font-size: 14.5px; color: var(--ink2); }
nav.links a:hover { color: var(--ink); }
.tools { margin-left: auto; display: flex; align-items: center; gap: 6px; }
.tg {
  height: 32px;
  min-width: 36px;
  padding: 0 10px;
  border: 1px solid var(--rule2);
  border-radius: 3px;
  font: 500 12px/1 var(--mono);
  color: var(--ink2);
}
.tg:hover { color: var(--ink); border-color: var(--ink3); }
.tg svg {
  width: 14px;
  height: 14px;
  display: block;
  stroke: currentColor;
  fill: none;
  stroke-width: 1.5;
}
.menu { display: none; }

/* hero */
.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  gap: 72px;
  padding: 76px 0 72px;
  border-bottom: 1px solid var(--rule);
}
.hero h1 {
  font: 400 54px/1.1 var(--serif);
  letter-spacing: -.018em;
  margin: 22px 0 26px;
  max-width: 640px;
}
:lang(zh-CN) .hero h1 {
  font: 600 44px/1.38 var(--zh-serif);
  letter-spacing: .01em;
}
.hero h1 em { font-style: italic; color: var(--acc); }
:lang(zh-CN) .hero h1 em { font-style: normal; }
.lede { font-size: 18px; line-height: 1.65; color: var(--ink2); max-width: 580px; }
:lang(zh-CN) .lede { font-size: 17px; line-height: 1.9; }
.cta { display: flex; align-items: center; gap: 28px; margin-top: 36px; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  height: 46px;
  padding: 0 22px;
  background: var(--ink);
  color: var(--bg);
  font: 500 14.5px/1 var(--sans);
  border-radius: 3px;
}
.lnk {
  font-size: 14.5px;
  font-weight: 500;
  border-bottom: 1px solid var(--rule2);
  padding-bottom: 3px;
}
.lnk:hover { border-color: var(--ink); }

/* lifecycle panel */
.cycle { border: 1px solid var(--rule); background: var(--surf); align-self: start; }
.cycle-h {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: 16px 20px;
  border-bottom: 1px solid var(--rule);
}
.cycle-h h2 { font: 600 14px/1.3 var(--sans); }
.cycle ol { list-style: none; }
.cycle li {
  display: grid;
  grid-template-columns: 34px 1fr;
  gap: 4px 12px;
  padding: 14px 20px;
  border-bottom: 1px solid var(--rule);
  position: relative;
}
.cycle li:last-child { border-bottom: 0; }
.cycle li .n { font: 500 12px/1.6 var(--mono); color: var(--ink3); padding-top: 1px; }
.cycle li h3 { font: 600 14.5px/1.4 var(--sans); }
.cycle li p { grid-column: 2; font-size: 13px; line-height: 1.5; color: var(--ink2); }
.cycle li .g { grid-column: 2; font: 500 11.5px/1.4 var(--mono); color: var(--acc); margin-top: 4px; }
.cycle li.own { background: var(--acc2); }
.cycle-f { padding: 12px 20px; border-top: 1px solid var(--rule); font-size: 12px; color: var(--ink3); }

/* sections */
section.s { padding: 72px 0; border-bottom: 1px solid var(--rule); }
.s-h {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1.8fr);
  gap: 72px;
  margin-bottom: 44px;
}
.s-h h2 { font: 400 34px/1.2 var(--serif); letter-spacing: -.012em; margin-top: 14px; }
:lang(zh-CN) .s-h h2 { font: 600 28px/1.4 var(--zh-serif); }
.s-h p { color: var(--ink2); font-size: 16.5px; max-width: 620px; align-self: end; }

.sys { display: grid; grid-template-columns: repeat(3, 1fr); border-top: 1px solid var(--ink); }
.sys article {
  padding: 26px 28px 30px 0;
  border-bottom: 1px solid var(--rule);
  display: flex;
  flex-direction: column;
}
.sys article:not(:nth-child(3n+1)) { padding-left: 28px; border-left: 1px solid var(--rule); }
.sys .k {
  display: flex;
  justify-content: space-between;
  font: 500 12px/1 var(--mono);
  color: var(--ink3);
  margin-bottom: 18px;
}
.sys h3 { font: 600 19px/1.3 var(--serif); margin-bottom: 10px; }
:lang(zh-CN) .sys h3 { font: 600 18px/1.45 var(--zh-serif); }
.sys p { font-size: 14.5px; line-height: 1.62; color: var(--ink2); flex: 1; }
.sys dl {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 6px 14px;
  margin-top: 18px;
  padding-top: 14px;
  border-top: 1px dashed var(--rule2);
  font-size: 12.5px;
}
.sys dt {
  font: 500 11.5px/1.5 var(--mono);
  color: var(--ink3);
  text-transform: uppercase;
  letter-spacing: .04em;
}
.sys dd { color: var(--ink); }

.prin { display: grid; grid-template-columns: repeat(2, 1fr); gap: 0 72px; counter-reset: p; }
.prin li {
  list-style: none;
  display: grid;
  grid-template-columns: 56px 1fr;
  padding: 24px 0;
  border-top: 1px solid var(--rule);
}
.prin li::before {
  counter-increment: p;
  content: counter(p, upper-roman) ".";
  font: 400 22px/1.2 var(--serif);
  color: var(--acc);
}
.prin h3 { font: 600 16.5px/1.4 var(--sans); margin-bottom: 6px; }
.prin p { font-size: 14.5px; color: var(--ink2); line-height: 1.62; }

.idx { border-top: 1px solid var(--ink); }
.idx .row {
  display: grid;
  grid-template-columns: 240px 1fr 150px 24px;
  align-items: baseline;
  gap: 28px;
  padding: 20px 0;
  border-bottom: 1px solid var(--rule);
}
.idx a.row:hover h3 {
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 1px;
}
.idx h3 { font: 600 17px/1.35 var(--serif); }
:lang(zh-CN) .idx h3 { font-family: var(--zh-serif); }
.idx p { font-size: 14.5px; color: var(--ink2); }
.idx .acc {
  font: 500 11.5px/1 var(--mono);
  color: var(--ink3);
  text-transform: uppercase;
  letter-spacing: .05em;
}
.idx .ar { font-family: var(--mono); color: var(--ink3); }

footer { padding: 44px 0 56px; }
footer .fin {
  border-top: 1px solid var(--ink);
  padding-top: 28px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 2fr);
  gap: 72px;
}
footer .disc { font-size: 13px; line-height: 1.7; color: var(--ink2); max-width: 640px; }
footer .meta {
  display: flex;
  justify-content: space-between;
  margin-top: 22px;
  font: 400 12px/1.6 var(--mono);
  color: var(--ink3);
  gap: 20px;
}

@media (max-width: 760px) {
  body { font-size: 15px; }
  .w { padding: 0 20px; }
  header .w {
    min-height: 60px;
    height: auto;
    flex-wrap: wrap;
    gap: 0 12px;
    padding-top: 8px;
    padding-bottom: 8px;
    align-items: center;
  }
  .mark { font-size: 15.5px; }
  nav.links {
    display: none;
    order: 5;
    flex: 0 0 100%;
    flex-direction: column;
    gap: 0;
    margin: 0 -20px;
    padding: 4px 20px 10px;
    border-top: 1px solid var(--rule);
  }
  nav.links[data-open=true] { display: flex; }
  nav.links a { padding: 10px 0; font-size: 15px; border-bottom: 1px solid var(--rule); }
  nav.links a:last-child { border-bottom: 0; }
  .tg { min-width: 32px; padding: 0 8px; height: 30px; }
  .menu { display: inline-flex; align-items: center; }
  .hero { grid-template-columns: 1fr; gap: 36px; padding: 40px 0 44px; }
  .hero h1 { font-size: 34px; line-height: 1.16; margin: 16px 0 18px; }
  :lang(zh-CN) .hero h1 { font-size: 28px; line-height: 1.45; }
  .lede { font-size: 15.5px; }
  :lang(zh-CN) .lede { font-size: 15px; }
  .cta { gap: 20px; margin-top: 26px; }
  .btn { height: 44px; padding: 0 18px; font-size: 14px; }
  .cycle li { padding: 12px 16px; }
  .cycle-h, .cycle-f { padding-left: 16px; padding-right: 16px; }
  section.s { padding: 48px 0; }
  .s-h { grid-template-columns: 1fr; gap: 12px; margin-bottom: 28px; }
  .s-h h2 { font-size: 26px; }
  :lang(zh-CN) .s-h h2 { font-size: 23px; }
  .s-h p { font-size: 15px; }
  .sys { grid-template-columns: 1fr; }
  .sys article, .sys article:not(:nth-child(3n+1)) { padding: 22px 0 24px; border-left: 0; }
  .prin { grid-template-columns: 1fr; }
  .prin li { grid-template-columns: 44px 1fr; padding: 18px 0; }
  .idx .row { grid-template-columns: 1fr 20px; gap: 4px 12px; padding: 16px 0; }
  .idx .row p { grid-column: 1; }
  .idx .row .acc { grid-row: 3; grid-column: 1; margin-top: 6px; }
  .idx .row .ar { grid-row: 1; grid-column: 2; }
  footer .fin { grid-template-columns: 1fr; gap: 16px; }
  footer .meta { flex-direction: column; gap: 4px; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}