:root {
  color-scheme: light;
  --ink: #14212b;
  --muted: #5e6a6f;
  --paper: #f3f1e9;
  --paper-deep: #e8e5da;
  --line: #a9b0ab;
  --cobalt: #1647d8;
  --cobalt-deep: #0d2a7a;
  --lime: #cfe85c;
  --coral: #ed6b4d;
  --serif: Georgia, "Times New Roman", serif;
  --sans: Arial, Helvetica, sans-serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; background: var(--paper); }

body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(90deg, transparent 0 8%, rgba(20, 33, 43, .035) 8% 8.08%, transparent 8.08% 91.9%, rgba(20, 33, 43, .035) 91.9% 92%, transparent 92%),
    var(--paper);
  font-family: var(--sans);
  line-height: 1.55;
}

body::before {
  content: "";
  display: block;
  height: 7px;
  background: linear-gradient(90deg, var(--cobalt) 0 38%, var(--lime) 38% 67%, var(--coral) 67% 100%);
}

a { color: var(--cobalt-deep); text-underline-offset: .16em; }
a:hover { color: var(--coral); }

button, input { font: inherit; }
button { cursor: pointer; }
button:focus-visible, input:focus-visible, a:focus-visible { outline: 3px solid var(--coral); outline-offset: 3px; }

.shell { width: min(1180px, calc(100% - 40px)); margin: 0 auto; }

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 74px;
  border-bottom: 1px solid var(--ink);
  gap: 24px;
}

.brand { color: var(--ink); text-decoration: none; font: 700 13px/1 var(--mono); letter-spacing: .1em; text-transform: uppercase; }
.brand span { color: var(--cobalt); }

.language-nav { display: flex; align-items: center; gap: 7px; font: 700 12px/1 var(--mono); letter-spacing: .04em; }
.language-nav a { color: var(--ink); text-decoration: none; border: 1px solid var(--ink); padding: 10px 12px; min-height: 42px; display: inline-flex; align-items: center; }
.language-nav a[aria-current="page"] { color: var(--paper); background: var(--ink); }

.hero { position: relative; padding: 74px 0 64px; border-bottom: 1px solid var(--ink); overflow: hidden; }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.08fr) minmax(310px, .92fr); gap: 70px; align-items: end; }
.eyebrow { margin: 0 0 18px; color: var(--cobalt-deep); font: 700 12px/1.25 var(--mono); letter-spacing: .09em; text-transform: uppercase; }
h1, h2, h3 { margin: 0; font-weight: 800; letter-spacing: -.045em; line-height: .98; }
h1 { max-width: 780px; font-size: clamp(4rem, 8.2vw, 8.7rem); }
h2 { font-size: clamp(2.45rem, 5vw, 5rem); }
h3 { font-size: clamp(1.6rem, 3vw, 2.6rem); }
.hero-deck { max-width: 650px; margin: 26px 0 0; font: 400 clamp(1.28rem, 2.1vw, 1.72rem)/1.24 var(--serif); }
.hero-note { max-width: 560px; margin: 19px 0 0; color: var(--muted); font-size: 14px; }

.pendulum-stage { position: relative; min-height: 340px; border-left: 1px solid var(--ink); display: flex; align-items: flex-end; justify-content: center; padding: 26px 20px 48px; }
.pendulum-stage::before { content: "g × ℓ"; position: absolute; top: 10px; left: 16px; font: 700 12px/1 var(--mono); color: var(--cobalt); }
.pendulum-stage::after { content: "v²"; position: absolute; right: 20px; bottom: 14px; font: 700 12px/1 var(--mono); color: var(--coral); }
.pendulum-floor { position: absolute; left: 11%; right: 6%; bottom: 47px; border-bottom: 2px solid var(--ink); }
.pendulum-arm { position: relative; width: 3px; height: 226px; background: var(--ink); transform-origin: bottom center; animation: swing 3.8s ease-in-out infinite; }
.pendulum-arm::before { content: ""; position: absolute; top: -8px; left: -7px; width: 17px; height: 17px; border-radius: 50%; background: var(--cobalt); }
.pendulum-arm::after { content: ""; position: absolute; bottom: -15px; left: -13px; width: 29px; height: 29px; border-radius: 50%; background: var(--coral); border: 5px solid var(--paper); outline: 2px solid var(--ink); }
@keyframes swing { 0%, 100% { transform: rotate(-13deg); } 50% { transform: rotate(13deg); } }

.hero-result { margin-top: 30px; display: flex; align-items: end; gap: 16px; border-top: 1px solid var(--ink); padding-top: 22px; }
.result-number { font: 800 clamp(4.4rem, 8vw, 7.6rem)/.78 var(--sans); letter-spacing: -.08em; color: var(--cobalt); }
.result-label { max-width: 190px; font: 700 13px/1.3 var(--mono); text-transform: uppercase; }

.main { padding-bottom: 90px; }
.reading-column { width: min(760px, 100%); margin: 0 auto; }
.section { padding: 90px 0 0; }
.section + .section { border-top: 1px solid var(--line); margin-top: 90px; }
.section-intro { max-width: 610px; margin: 24px 0 0; font: 400 1.28rem/1.45 var(--serif); }
.prose { max-width: 660px; margin-top: 28px; font-size: 1.07rem; }
.prose p { margin: 0 0 22px; }
.prose strong { color: var(--cobalt-deep); }

.energy-figure { margin: 46px 0 0; border-top: 2px solid var(--ink); border-bottom: 1px solid var(--ink); padding: 24px 0 18px; }
.energy-figure svg { display: block; width: 100%; height: auto; overflow: visible; }
.energy-figure figcaption { margin-top: 15px; color: var(--muted); font: 12px/1.45 var(--mono); }
.energy-label { font: 700 13px var(--mono); fill: var(--ink); }
.energy-label-accent { font: 700 16px var(--mono); fill: var(--cobalt); }

.comparison { margin: 42px 0 0; display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.comparison-item { border-top: 5px solid var(--cobalt); padding-top: 16px; }
.comparison-item:last-child { border-color: var(--coral); }
.comparison-value { display: block; font: 800 clamp(3rem, 7vw, 5.5rem)/.85 var(--sans); letter-spacing: -.08em; }
.comparison-item:last-child .comparison-value { color: var(--coral); }
.comparison-label { display: block; margin-top: 12px; font: 700 12px/1.35 var(--mono); text-transform: uppercase; }
.comparison-note { grid-column: 1/-1; margin: 0; color: var(--muted); font-size: 13px; }

.scale { margin: 42px 0 0; }
.scale-rail { position: relative; height: 72px; border-top: 2px solid var(--ink); border-bottom: 1px solid var(--line); }
.scale-rail::before, .scale-rail::after { content: ""; position: absolute; top: -8px; height: 14px; border-left: 2px solid var(--ink); }
.scale-rail::before { left: 0; }
.scale-rail::after { right: 0; }
.scale-marker { position: absolute; top: -11px; left: 62.5%; height: 22px; border-left: 5px solid var(--coral); }
.scale-marker span { position: absolute; top: 29px; left: -25px; width: 90px; font: 700 12px/1.25 var(--mono); color: var(--coral); }
.scale-labels { display: flex; justify-content: space-between; margin-top: 10px; font: 700 11px/1.2 var(--mono); }

.instrument { margin-top: 44px; padding: 30px; background: var(--ink); color: var(--paper); border: 1px solid var(--ink); position: relative; }
.instrument::after { content: "MEASURE / MODEL"; position: absolute; right: 22px; top: 22px; color: var(--lime); font: 700 10px/1 var(--mono); letter-spacing: .1em; }
.instrument h3 { max-width: 520px; color: var(--paper); }
.instrument .section-intro { color: #dbe0d7; font-size: 1.15rem; max-width: 610px; }
.input-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 17px; margin-top: 28px; }
.input-label { display: flex; flex-direction: column; gap: 8px; color: #dbe0d7; font: 700 11px/1.25 var(--mono); text-transform: uppercase; }
.input-label span { color: #a9b7ae; font-weight: 400; text-transform: none; }
.input-label input { width: 100%; min-height: 48px; border: 1px solid #7f8c83; background: #1c2c38; color: white; padding: 10px 12px; border-radius: 0; }
.button-row { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 20px; }
.button { min-height: 46px; border: 1px solid var(--lime); padding: 11px 14px; background: var(--lime); color: var(--ink); font: 700 12px/1 var(--mono); }
.button.secondary { background: transparent; color: var(--paper); border-color: #9aa89d; }
.button:hover { background: white; border-color: white; color: var(--ink); }
.timer-readout { min-height: 21px; margin: 14px 0 0; color: #dbe0d7; font: 700 12px/1.35 var(--mono); }
.results { display: grid; grid-template-columns: repeat(3, 1fr); margin-top: 32px; border-top: 1px solid #62716a; border-bottom: 1px solid #62716a; }
.result-cell { padding: 18px 13px 17px; border-right: 1px solid #62716a; }
.result-cell:last-child { border-right: 0; }
.result-cell strong { display: block; color: var(--lime); font: 800 clamp(1.9rem, 4vw, 3.1rem)/.9 var(--sans); letter-spacing: -.06em; }
.result-cell span { display: block; margin-top: 10px; color: #dbe0d7; font: 700 10px/1.25 var(--mono); text-transform: uppercase; }
.instrument-output { margin: 22px 0 0; color: var(--paper); font: 700 14px/1.4 var(--mono); }
.instrument-transition { margin: 15px 0 0; color: #bfcac1; font: 12px/1.4 var(--mono); }
.instrument-transition strong { color: var(--lime); font-size: 15px; }
.meter { margin-top: 20px; }
.meter-track { position: relative; height: 14px; background: #3a4b51; border: 1px solid #77867e; }
.meter-track::after { content: ""; position: absolute; left: 62.5%; top: -7px; height: 26px; border-left: 2px solid var(--coral); }
.meter-fill { position: absolute; inset: 0 auto 0 0; width: 27%; background: var(--lime); transition: width .18s ease-out; }
.meter-caption { display: flex; justify-content: space-between; margin-top: 10px; color: #a9b7ae; font: 10px/1.3 var(--mono); }
.method-note { margin-top: 22px; padding-top: 16px; border-top: 1px solid #62716a; color: #bfcac1; font-size: 12px; }

.limit-note { margin-top: 34px; border-left: 5px solid var(--coral); padding: 2px 0 2px 20px; }
.limit-note p { margin: 0; font-size: 1.03rem; }
.source-list { margin: 26px 0 0; padding-left: 22px; }
.source-list li { margin: 0 0 13px; padding-left: 4px; }
.source-list a { font-weight: 700; }
.footer { padding: 26px 0 60px; border-top: 1px solid var(--ink); color: var(--muted); font: 12px/1.5 var(--mono); }
.footer p { margin: 0; }
.footer-nav { display: flex; justify-content: space-between; gap: 16px; margin-bottom: 16px; }
.back-top { color: var(--ink); }

.not-found { min-height: 60vh; padding: 100px 0; }
.not-found p { max-width: 540px; font: 1.3rem/1.4 var(--serif); }

@media (max-width: 760px) {
  .shell { width: min(100% - 28px, 680px); }
  .site-header { min-height: 66px; }
  .brand { font-size: 11px; }
  .language-nav a { padding: 9px 10px; }
  .hero { padding: 49px 0 44px; }
  .hero-grid { grid-template-columns: 1fr; gap: 42px; }
  h1 { font-size: clamp(3.55rem, 17vw, 6rem); }
  .hero-deck { font-size: 1.28rem; }
  .pendulum-stage { min-height: 250px; padding-bottom: 37px; border-left: 0; border-top: 1px solid var(--ink); }
  .pendulum-arm { height: 170px; }
  .pendulum-floor { bottom: 36px; }
  .hero-result { margin-top: 20px; }
  .result-number { font-size: 5rem; }
  .section { padding-top: 66px; }
  .section + .section { margin-top: 66px; }
  .section-intro { font-size: 1.18rem; }
  .comparison { gap: 18px; }
  .comparison-value { font-size: 3.3rem; }
  .instrument { margin-left: 0; margin-right: 0; padding: 24px 18px; }
  .instrument::after { position: static; display: block; margin-bottom: 20px; }
  .input-grid { grid-template-columns: 1fr; gap: 13px; }
  .results { grid-template-columns: 1fr 1fr; }
  .result-cell { border-bottom: 1px solid #62716a; }
  .result-cell:nth-child(2) { border-right: 0; }
  .result-cell:last-child { grid-column: 1/-1; border-bottom: 0; border-right: 0; }
  .footer-nav { align-items: flex-start; flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}