/* ============================================================
   我们从没被演化设计成喜欢运动
   A reading of Daniel Lieberman's Exercised, built on the primary
   literature it rests on.
   ============================================================ */

:root {
  --ink: #1c1b18;
  --paper: #f2efe4;
  --paper-bright: #fbf9f2;
  --paper-warm: #ebe5d6;

  --cost: #bf5b28;        /* 省力本能 / 代价 */
  --restore: #3f7d52;     /* 活动 / 收益 */
  --signal: #dcb43a;      /* 高亮，克制使用 */
  --deep: #26332a;        /* 反色区块 */
  --muted-line: #8d8878;

  --line: rgba(28, 27, 24, 0.2);
  --line-soft: rgba(28, 27, 24, 0.1);
  --muted: #5f5c52;
  --shadow: 0 24px 70px rgba(28, 27, 24, 0.13);
  --shadow-soft: 0 10px 34px rgba(28, 27, 24, 0.08);

  --mono: "DM Mono", ui-monospace, "SF Mono", Menlo, monospace;
  --sans: "Space Grotesk", "PingFang SC", "HarmonyOS Sans SC", "Noto Sans SC",
    "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --han: "PingFang SC", "HarmonyOS Sans SC", "Noto Sans SC", "Hiragino Sans GB",
    "Source Han Sans SC", "Microsoft YaHei", system-ui, sans-serif;
  --han-serif: "Songti SC", "Noto Serif SC", "Source Han Serif SC", "SimSun", Georgia, serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--han);
  font-size: 16px;
  line-height: 1.78;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { max-width: 100%; }

a { color: inherit; }

/* ---------- progress ---------- */
.reading-progress {
  position: fixed;
  inset: 0 0 auto;
  z-index: 200;
  height: 3px;
  background: rgba(28, 27, 24, 0.07);
}
.reading-progress span {
  display: block;
  width: 0;
  height: 100%;
  background: var(--cost);
  transition: width 0.1s linear;
}

/* ---------- topbar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 150;
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 12px clamp(16px, 3.2vw, 40px);
  background: rgba(244, 241, 232, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line-soft);
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font: 500 10.5px/1.5 var(--mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
  white-space: nowrap;
}
.brand-mark {
  display: inline-grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--deep);
  color: var(--paper-bright);
  font-family: var(--han);
  font-size: 11px;
  letter-spacing: 0;
}
.topbar nav {
  display: flex;
  gap: clamp(10px, 1.5vw, 22px);
  margin-left: auto;
  overflow-x: auto;
  scrollbar-width: none;
}
.topbar nav::-webkit-scrollbar { display: none; }
.topbar nav a {
  text-decoration: none;
  color: var(--muted);
  font-size: 13px;
  white-space: nowrap;
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}
.topbar nav a:hover { color: var(--ink); border-color: var(--cost); }

/* ---------- layout ---------- */
main { display: block; }
section { padding: clamp(56px, 8vw, 118px) clamp(16px, 4vw, 48px); }
.wrap { max-width: 1180px; margin: 0 auto; }
.narrow { max-width: 780px; }

.kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 18px;
  font: 500 10px/1.6 var(--mono);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}
.kicker::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--cost);
}

h1, h2, h3, h4 { font-family: var(--han); font-weight: 600; }
h1 {
  margin: 0 0 22px;
  font-size: clamp(32px, 5vw, 62px);
  line-height: 1.16;
  letter-spacing: -0.02em;
}
h2 {
  margin: 0 0 20px;
  font-size: clamp(26px, 3.7vw, 44px);
  line-height: 1.22;
  letter-spacing: -0.02em;
}
h3 {
  margin: 0 0 12px;
  font-size: clamp(19px, 2.1vw, 26px);
  line-height: 1.34;
  letter-spacing: -0.01em;
}
h4 { margin: 0 0 8px; font-size: 16px; line-height: 1.5; }

p { margin: 0 0 18px; }
.lead {
  max-width: 820px;
  font-size: clamp(16.5px, 1.5vw, 20px);
  line-height: 1.82;
  color: #3c3a33;
}
.muted { color: var(--muted); }
em { font-family: var(--han-serif); font-style: normal; }
strong { font-weight: 600; }

.num { font-family: var(--mono); font-feature-settings: "tnum"; }

.cite {
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.02em;
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}
.cite:hover { color: var(--cost); border-color: var(--cost); }

/* ---------- hero ---------- */
.hero {
  padding-top: clamp(44px, 6vw, 84px);
  background:
    radial-gradient(1100px 520px at 78% -12%, rgba(43, 131, 120, 0.14), transparent 62%),
    radial-gradient(900px 460px at 8% 8%, rgba(207, 81, 56, 0.1), transparent 60%);
}
.hero-grid {
  max-width: 1180px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.02fr 1fr;
  gap: clamp(30px, 4.5vw, 66px);
  align-items: center;
}
.eyebrow {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 14px;
  margin: 0 0 24px;
  font: 500 10px/1.6 var(--mono);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--muted);
}
.eyebrow span {
  padding: 4px 10px;
  border: 1px solid var(--line);
  border-radius: 100px;
}
.hero h1 em {
  font-family: var(--han-serif);
  color: var(--cost);
}
.hero-deck { max-width: 620px; font-size: clamp(15.5px, 1.35vw, 18px); color: #3c3a33; }
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  margin-top: 30px;
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--muted);
}
.primary-button, .ghost-button {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 12px 22px;
  border-radius: 100px;
  text-decoration: none;
  font-family: var(--han);
  font-size: 14px;
  font-weight: 500;
  transition: transform 0.2s ease, background 0.2s ease, color 0.2s ease;
}
.primary-button { background: var(--deep); color: var(--paper-bright); }
.primary-button:hover { transform: translateY(-2px); }
.ghost-button { border: 1px solid var(--line); color: var(--ink); }
.ghost-button:hover { background: var(--paper-bright); transform: translateY(-2px); }

.hero-stage {
  padding: 20px;
  background: var(--paper-bright);
  border: 1px solid var(--line-soft);
  border-radius: 4px;
  box-shadow: var(--shadow);
}
.hero-stage svg { display: block; width: 100%; height: auto; }
.stage-note {
  margin: 14px 0 0;
  padding-top: 12px;
  border-top: 1px solid var(--line-soft);
  font-size: 12.5px;
  line-height: 1.62;
  color: var(--muted);
}

/* ---------- fact strip ---------- */
.facts {
  max-width: 1180px;
  margin: clamp(44px, 6vw, 78px) auto 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}
.fact {
  padding: 22px 20px;
  background: var(--paper);
}
.fact b {
  display: block;
  font-family: var(--mono);
  font-size: clamp(22px, 2.6vw, 32px);
  font-weight: 500;
  letter-spacing: -0.02em;
  line-height: 1.1;
  color: var(--cost);
}
.fact span {
  display: block;
  margin-top: 9px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--muted);
}

/* ---------- generic blocks ---------- */
.alt { background: var(--paper-warm); }

.claim-block {
  margin: clamp(36px, 5vw, 60px) 0 0;
  padding: clamp(26px, 3.4vw, 42px);
  background: var(--deep);
  color: #eef0ec;
  border-radius: 4px;
}
.claim-block h3 { color: #fff; margin-bottom: 14px; }
.claim-block p { color: rgba(238, 240, 236, 0.82); margin-bottom: 0; max-width: 760px; }
.claim-block .kicker { color: rgba(238, 240, 236, 0.6); }
.claim-block .kicker::before { background: var(--signal); }
.claim-block .cite { color: rgba(238, 240, 236, 0.66); border-color: rgba(238, 240, 236, 0.3); }
.claim-block .cite:hover { color: var(--signal); border-color: var(--signal); }

/* beat: prose beside one panel */
.beat {
  max-width: 1180px;
  margin: clamp(44px, 6vw, 82px) auto 0;
  display: grid;
  grid-template-columns: 0.82fr 1.18fr;
  gap: clamp(26px, 4vw, 56px);
  align-items: center;
}
.beat.reverse { grid-template-columns: 1.18fr 0.82fr; }

/* 整幅宽度的图：文字在上，图占满栏宽 */
.figure-block { max-width: 1180px; margin: clamp(44px, 6vw, 82px) auto 0; }
.figure-block-copy { max-width: 820px; margin-bottom: clamp(20px, 2.6vw, 30px); }
.figure-block-copy p:last-child { margin-bottom: 0; }

.beat.reverse .beat-copy { order: 2; }
.beat-copy p:last-child { margin-bottom: 0; }
.beat-figure {
  margin: 0;
  padding: 18px;
  background: var(--paper-bright);
  border: 1px solid var(--line-soft);
  border-radius: 4px;
  box-shadow: var(--shadow-soft);
}
.beat-figure svg { display: block; width: 100%; height: auto; }
.beat-figure figcaption {
  margin-top: 15px;
  padding-top: 13px;
  border-top: 1px solid var(--line-soft);
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.68;
}
.beat-figure figcaption b { color: var(--ink); font-weight: 600; }

/* ---------- interactive lab ---------- */
.lab {
  max-width: 1180px;
  margin: clamp(40px, 5.5vw, 74px) auto 0;
  padding: clamp(20px, 2.6vw, 32px);
  background: var(--paper-bright);
  border: 1px solid var(--line);
  border-radius: 4px;
  box-shadow: var(--shadow);
}
.lab-head {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 20px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--line-soft);
}
.lab-head h3 { margin: 0; }
.lab-head .kicker { margin: 0; }
.lab-body { display: grid; grid-template-columns: 1fr 300px; gap: clamp(20px, 2.6vw, 34px); align-items: start; }
.lab-body.wide-controls { grid-template-columns: 1fr 340px; }
.lab-canvas { overflow-x: auto; }
.lab-canvas svg { display: block; width: 100%; height: auto; min-width: 460px; }

.controls { display: grid; gap: 16px; }
.control-group { display: grid; gap: 9px; }
.control-label {
  font: 500 10px/1.6 var(--mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}
.btn-row { display: flex; flex-wrap: wrap; gap: 8px; }
.pill {
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 100px;
  background: transparent;
  color: var(--ink);
  font-family: var(--han);
  font-size: 13px;
  cursor: pointer;
  transition: background 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}
.pill:hover { border-color: var(--ink); }
.pill.active { background: var(--deep); border-color: var(--deep); color: var(--paper-bright); }
.pill.active.cost-active { background: var(--cost); border-color: var(--cost); }
.pill.active.restore-active { background: var(--restore); border-color: var(--restore); }
.pill:focus-visible { outline: 2px solid var(--signal); outline-offset: 2px; }

.toggle-row { display: grid; gap: 7px; }
.toggle {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  border: 1px solid var(--line-soft);
  border-radius: 3px;
  background: transparent;
  color: var(--ink);
  font-family: var(--han);
  font-size: 13px;
  text-align: left;
  cursor: pointer;
  transition: background 0.18s ease, border-color 0.18s ease;
}
.toggle:hover { border-color: var(--line); }
.toggle[aria-pressed="true"] { background: rgba(28, 27, 24, 0.04); border-color: var(--line); }
.toggle:focus-visible { outline: 2px solid var(--signal); outline-offset: 2px; }
.swatch { width: 22px; height: 3px; border-radius: 2px; flex: none; }
.toggle .state { margin-left: auto; font-family: var(--mono); font-size: 10.5px; color: var(--muted); }

input[type="range"] { width: 100%; accent-color: var(--cost); }

.readout {
  padding: 15px 16px;
  background: var(--paper-warm);
  border-left: 3px solid var(--cost);
  border-radius: 0 3px 3px 0;
  font-size: 13.5px;
  line-height: 1.7;
}
.readout b { font-weight: 600; }
.readout .rd-title {
  display: block;
  margin-bottom: 6px;
  font: 500 10px/1.6 var(--mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

.lab-caption {
  margin: 18px 0 0;
  padding-top: 14px;
  border-top: 1px solid var(--line-soft);
  font-size: 12.5px;
  line-height: 1.68;
  color: var(--muted);
}
.lab-caption b { color: var(--ink); font-weight: 600; }

.schematic-tag {
  display: inline-block;
  padding: 2px 8px;
  border: 1px solid var(--line);
  border-radius: 100px;
  font: 500 9.5px/1.7 var(--mono);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  vertical-align: 2px;
}

/* ---------- cards ---------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 18px;
  margin-top: clamp(30px, 4vw, 46px);
}
.card {
  padding: 22px 22px 24px;
  background: var(--paper-bright);
  border: 1px solid var(--line-soft);
  border-radius: 4px;
}
.card h4 { font-size: 16.5px; }
.card p { margin-bottom: 0; font-size: 14px; line-height: 1.72; color: var(--muted); }
.card .tag {
  display: inline-block;
  margin-bottom: 12px;
  padding: 3px 9px;
  border-radius: 100px;
  font: 500 9.5px/1.7 var(--mono);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}
.tag.no { background: rgba(207, 81, 56, 0.12); color: #a03a25; }
.tag.yes { background: rgba(43, 131, 120, 0.13); color: #1d6459; }
.tag.maybe { background: rgba(217, 192, 46, 0.2); color: #7a6a10; }

/* ---------- edges ---------- */
.edges { counter-reset: edge; display: grid; gap: 2px; margin-top: clamp(30px, 4vw, 46px); }
.edge {
  display: grid;
  grid-template-columns: 68px 1fr;
  gap: clamp(16px, 2.4vw, 30px);
  padding: 24px 0;
  border-top: 1px solid var(--line-soft);
}
.edge:last-child { border-bottom: 1px solid var(--line-soft); }
.edge::before {
  counter-increment: edge;
  content: counter(edge, decimal-leading-zero);
  font-family: var(--mono);
  font-size: 22px;
  color: var(--cost);
  line-height: 1.2;
}
.edge h4 { margin-bottom: 7px; font-size: 17px; }
.edge p { margin-bottom: 0; font-size: 14.5px; line-height: 1.76; color: var(--muted); }

/* ---------- takeaway flow ---------- */
.flow {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin: clamp(30px, 4vw, 46px) 0;
}
.flow-step {
  position: relative;
  padding: 20px 18px;
  background: var(--paper-bright);
  border: 1px solid var(--line-soft);
  border-radius: 4px;
}
.flow-step .n {
  display: block;
  margin-bottom: 10px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--cost);
}
.flow-step h4 { font-size: 15.5px; }
.flow-step p { margin: 0; font-size: 13.5px; line-height: 1.7; color: var(--muted); }

/* ---------- sources ---------- */
.source-list { display: grid; gap: 2px; margin-top: clamp(26px, 3.4vw, 40px); }
.source-item {
  display: grid;
  grid-template-columns: 132px 1fr;
  gap: clamp(14px, 2vw, 26px);
  padding: 18px 0;
  border-top: 1px solid var(--line-soft);
  font-size: 14px;
  line-height: 1.7;
}
.source-item:last-child { border-bottom: 1px solid var(--line-soft); }
.source-item .src-key {
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.03em;
  color: var(--muted);
  padding-top: 3px;
}
.source-item a { color: var(--ink); text-decoration: none; border-bottom: 1px solid var(--line); }
.source-item a:hover { color: var(--cost); border-color: var(--cost); }
.source-item .src-note { display: block; margin-top: 5px; font-size: 12.5px; color: var(--muted); }

.colophon {
  max-width: 1180px;
  margin: 0 auto;
  padding-top: clamp(30px, 4vw, 44px);
  border-top: 1px solid var(--line-soft);
  font-size: 12.5px;
  line-height: 1.78;
  color: var(--muted);
}
.colophon p { max-width: 820px; }

footer {
  padding: 30px clamp(16px, 4vw, 48px) 46px;
  border-top: 1px solid var(--line-soft);
  font: 500 10.5px/1.7 var(--mono);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  text-align: center;
}

/* ---------- svg text defaults ---------- */
svg text {
  font-family: var(--han);
  fill: var(--ink);
}
svg .lbl { font-size: 11px; fill: var(--muted); }
svg .lbl-sm { font-size: 9.5px; fill: var(--muted); font-family: var(--mono); }
svg .lbl-b { font-size: 12px; font-weight: 600; }
svg .axis { stroke: var(--line); stroke-width: 1; }
svg .grid { stroke: var(--line-soft); stroke-width: 1; stroke-dasharray: 3 4; }

/* ---------- reveal ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.reveal.visible { opacity: 1; transform: none; }

/* ---------- responsive ---------- */
@media (max-width: 1020px) {
  .hero-grid { grid-template-columns: 1fr; }
  .beat { grid-template-columns: 1fr; }
  .beat.reverse { grid-template-columns: 1fr; }
  .beat.reverse .beat-copy { order: 0; }
  .lab-body, .lab-body.wide-controls { grid-template-columns: 1fr; }
  .facts { grid-template-columns: repeat(2, 1fr); }
  .flow { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 720px) {
  body { font-size: 15.5px; }
  .facts { grid-template-columns: 1fr; }
  .flow { grid-template-columns: 1fr; }
  .edge { grid-template-columns: 1fr; gap: 10px; }
  .source-item { grid-template-columns: 1fr; gap: 6px; }
  .topbar nav { display: none; }
  .lab-canvas svg { min-width: 380px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}