:root {
  color-scheme: light;
  --ink: #172033;
  --muted: #687287;
  --paper: #f5f2e9;
  --surface: rgba(255, 255, 255, 0.74);
  --solid: #fffdf8;
  --line: rgba(23, 32, 51, 0.14);
  --coral: #ff6b5f;
  --coral-dark: #df4d43;
  --blue: #6e9df8;
  --lime: #c7ef68;
  --yellow: #ffd65a;
  --violet: #a184ff;
  --shadow: 0 24px 70px rgba(36, 43, 67, 0.12);
  --radius: 28px;
  --mono: "Cascadia Code", "SFMono-Regular", Consolas, monospace;
  --sans: Inter, "Microsoft YaHei UI", "PingFang SC", system-ui, sans-serif;
}

[data-theme="dark"] {
  color-scheme: dark;
  --ink: #eff2f9;
  --muted: #9ba6ba;
  --paper: #0e1420;
  --surface: rgba(24, 33, 50, 0.84);
  --solid: #182132;
  --line: rgba(222, 231, 249, 0.13);
  --shadow: 0 28px 80px rgba(0, 0, 0, 0.3);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 94px; }
body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--sans);
  line-height: 1.6;
  overflow-x: hidden;
}

button,
input,
select { font: inherit; color: inherit; }
button,
a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; text-decoration: none; }
button { cursor: pointer; }
canvas { max-width: 100%; }
::selection { color: #172033; background: var(--lime); }

.noise {
  position: fixed;
  inset: 0;
  z-index: -1;
  opacity: 0.19;
  pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 180 180' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='.13'/%3E%3C/svg%3E");
}

.orb {
  position: fixed;
  z-index: -2;
  width: 440px;
  height: 440px;
  border-radius: 50%;
  filter: blur(100px);
  opacity: 0.16;
  pointer-events: none;
}
.orb-a { top: 12%; left: -190px; background: var(--coral); }
.orb-b { top: 52%; right: -210px; background: var(--blue); }
.shell { width: min(1180px, calc(100% - 48px)); margin-inline: auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 32px;
  height: 78px;
  padding: 0 max(24px, calc((100vw - 1360px) / 2));
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--paper) 82%, transparent);
  backdrop-filter: blur(20px);
}

.brand { display: flex; align-items: center; gap: 11px; white-space: nowrap; }
.brand-mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  color: #172033;
  background: var(--lime);
  border: 2px solid #172033;
  border-radius: 12px;
  box-shadow: 3px 3px 0 #172033;
  font-weight: 950;
  transform: rotate(-4deg);
}
.brand b { display: block; font: 800 14px/1 var(--mono); letter-spacing: 0.09em; }
.brand small { color: var(--muted); font: 600 8px/1 var(--mono); letter-spacing: 0.14em; }
.page-nav { display: flex; align-items: center; gap: 4px; margin: auto; }
.page-nav a {
  padding: 8px 13px;
  color: var(--muted);
  border-radius: 30px;
  font-size: 14px;
  font-weight: 650;
  transition: color 0.2s, background 0.2s;
}
.page-nav a:hover { color: var(--ink); background: var(--surface); }
.header-actions { display: flex; align-items: center; gap: 10px; }
.local-pill { display: flex; align-items: center; gap: 7px; color: var(--muted); font: 700 9px var(--mono); letter-spacing: 0.08em; }
.local-pill i,
.privacy-note i { width: 7px; height: 7px; background: #79c95b; border-radius: 50%; box-shadow: 0 0 0 4px rgba(121, 201, 91, 0.14); }
.back-link,
.menu-toggle {
  min-height: 38px;
  padding: 0 15px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
  font-size: 13px;
  font-weight: 750;
}
.back-link { display: inline-flex; align-items: center; gap: 12px; }
.menu-toggle { display: none; width: 42px; padding: 0; }

.hero {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  align-items: center;
  gap: 68px;
  min-height: calc(100vh - 78px);
  padding-block: 70px 88px;
}
.kicker { margin: 0; color: var(--coral-dark); font: 750 11px var(--mono); letter-spacing: 0.12em; }
.kicker span { margin-right: 8px; }
.hero h1 {
  margin: 22px 0 25px;
  font-size: clamp(47px, 5.7vw, 79px);
  line-height: 1.08;
  letter-spacing: -0.06em;
}
.hero h1 em,
.model-copy h2 em { position: relative; color: var(--coral); font-style: normal; }
.hero h1 em::after {
  content: "";
  position: absolute;
  right: 1%;
  bottom: -7px;
  left: 2%;
  height: 10px;
  border-top: 3px solid currentColor;
  border-radius: 50%;
  transform: rotate(-1deg);
}
.hero-lead { max-width: 640px; margin: 0; color: var(--muted); font-size: 17px; }
.hero-actions { display: flex; align-items: center; gap: 24px; margin-top: 36px; }
.primary-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 22px;
  min-height: 48px;
  padding: 0 22px;
  color: white;
  background: var(--ink);
  border: 1px solid var(--ink);
  border-radius: 15px;
  box-shadow: 4px 4px 0 var(--coral);
  font-weight: 800;
  transition: transform 0.18s, box-shadow 0.18s;
}
[data-theme="dark"] .primary-button { color: #101725; background: #eff2f9; }
.primary-button:hover { transform: translate(-2px, -2px); box-shadow: 6px 6px 0 var(--coral); }
.text-button { font-weight: 750; border-bottom: 1px solid var(--ink); }
.hero-meta { display: flex; gap: 28px; margin-top: 54px; color: var(--muted); font: 600 10px var(--mono); text-transform: uppercase; }
.hero-meta b { display: block; color: var(--ink); font-size: 16px; }

.hero-visual {
  position: relative;
  display: grid;
  place-items: center;
  min-height: 570px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 44% 56% 58% 42% / 47% 43% 57% 53%;
  background: radial-gradient(circle at 50% 42%, color-mix(in srgb, var(--blue) 27%, var(--surface)), var(--surface) 68%);
  box-shadow: var(--shadow);
  animation: morph 11s ease-in-out infinite;
}
@keyframes morph { 50% { border-radius: 56% 44% 43% 57% / 55% 58% 42% 45%; } }
#heroCanvas { width: 100%; height: 100%; min-height: 560px; }
.telemetry {
  position: absolute;
  min-width: 135px;
  padding: 12px 15px;
  color: #172033;
  border: 2px solid #172033;
  border-radius: 15px;
  box-shadow: 4px 4px 0 #172033;
}
.telemetry small { display: block; font: 750 8px var(--mono); letter-spacing: 0.12em; }
.telemetry b { font: 900 17px var(--mono); }
.telemetry-power { top: 68px; left: 30px; background: var(--lime); transform: rotate(-4deg); }
.telemetry-speed { right: 28px; bottom: 86px; background: var(--yellow); transform: rotate(4deg); }
.coordinate { position: absolute; top: 42%; right: 22px; color: var(--muted); font: 650 8px/1.7 var(--mono); text-align: right; }

.ticker { width: 100%; overflow: hidden; color: #172033; background: var(--lime); border-block: 2px solid #172033; transform: rotate(-0.65deg) scale(1.01); }
.ticker div { width: max-content; padding: 13px 0; font: 900 12px var(--mono); letter-spacing: 0.12em; animation: ticker 30s linear infinite; }
.ticker span { margin: 0 22px; }
@keyframes ticker { to { transform: translateX(-50%); } }

.calculator-section,
.content-section { padding-block: 110px; }
.section-heading { display: flex; align-items: end; justify-content: space-between; gap: 24px; margin-bottom: 38px; }
.section-heading p { margin: 0; color: var(--coral-dark); font: 700 10px var(--mono); letter-spacing: 0.12em; }
.section-heading h2 { margin: 7px 0 0; font-size: clamp(31px, 4vw, 49px); line-height: 1.1; letter-spacing: -0.04em; }
.section-heading > span { max-width: 330px; color: var(--muted); font: 600 10px/1.6 var(--mono); text-align: right; }

.calculator {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 34px;
  background: var(--surface);
  box-shadow: var(--shadow);
}
.calc-primary { display: grid; grid-template-columns: 1fr auto 1fr; align-items: stretch; border-bottom: 1px solid var(--line); background: var(--solid); }
.hero-field { display: grid; gap: 10px; padding: 30px 34px; }
.hero-field > span:first-child { display: flex; align-items: center; gap: 10px; font-size: 13px; font-weight: 850; }
.hero-field > span:first-child i { color: var(--muted); font: 700 9px var(--mono); font-style: normal; }
.hero-field em { color: var(--muted); font-size: 11px; font-style: normal; }
.big-input { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: baseline; gap: 10px; }
.big-input input {
  width: 100%;
  min-width: 0;
  padding: 0;
  border: 0;
  outline: 0;
  background: transparent;
  font: 900 clamp(38px, 5vw, 65px) var(--mono);
  letter-spacing: -0.08em;
}
.big-input small { color: var(--muted); font: 800 15px var(--mono); }
.direction-mark { display: grid; place-items: center; width: 64px; color: #172033; background: var(--yellow); border-inline: 1px solid var(--line); font: 900 25px var(--mono); }
.range-row { display: grid; gap: 11px; padding: 20px 34px; border-bottom: 1px solid var(--line); }
.range-row > span { display: flex; justify-content: space-between; color: var(--muted); font-size: 12px; font-weight: 750; }
.range-row b { color: var(--ink); font-family: var(--mono); }
input[type="range"] { width: 100%; height: 24px; margin: 0; padding: 0; accent-color: var(--coral); background: transparent; }

.conditions-head { display: flex; align-items: end; justify-content: space-between; gap: 24px; padding: 28px 34px 18px; background: color-mix(in srgb, var(--blue) 12%, var(--surface)); }
.conditions-head small,
.prediction-copy small { color: var(--coral-dark); font: 750 9px var(--mono); letter-spacing: 0.12em; }
.conditions-head h3,
.prediction-copy h3 { margin: 3px 0 0; font-size: 22px; }
.unit-select { width: min(250px, 45%); color: var(--muted); font-size: 11px; font-weight: 750; }

input,
select {
  width: 100%;
  min-width: 0;
  height: 43px;
  margin-top: 7px;
  padding: 9px 12px;
  color: var(--ink);
  background: color-mix(in srgb, var(--solid) 92%, transparent);
  border: 1px solid var(--line);
  border-radius: 12px;
  outline: 0;
}
input:focus,
select:focus,
button:focus-visible,
a:focus-visible { border-color: var(--coral); outline: 3px solid color-mix(in srgb, var(--coral) 20%, transparent); outline-offset: 2px; }
.field-grid { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); border-top: 1px solid var(--line); }
.field-grid > label,
.hint-card { min-width: 0; min-height: 118px; padding: 20px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); font-size: 12px; font-weight: 750; }
.field-grid > :nth-child(5n) { border-right: 0; }
.input-unit { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center; gap: 8px; }
.input-unit small { min-width: 30px; color: var(--muted); font: 700 10px var(--mono); white-space: nowrap; }
.hint-card { color: #172033; background: var(--lime); }
.hint-card span { font-weight: 900; }
.hint-card p { margin: 8px 0 0; font-size: 11px; font-weight: 650; line-height: 1.5; }

.prediction-grid { display: grid; grid-template-columns: 1.25fr repeat(3, 1fr); background: var(--solid); border-bottom: 1px solid var(--line); }
.prediction-copy,
.prediction-grid > label { padding: 24px 26px; border-right: 1px solid var(--line); }
.prediction-copy p { max-width: 390px; margin: 8px 0 0; color: var(--muted); font-size: 12px; }
.prediction-grid > label { font-size: 12px; font-weight: 750; }
.prediction-grid > label:last-child { border-right: 0; }
.result-strip { display: grid; grid-template-columns: repeat(4, 1fr); background: color-mix(in srgb, var(--coral) 9%, var(--surface)); }
.result-strip div { min-width: 0; padding: 22px 25px; border-right: 1px solid var(--line); }
.result-strip div:last-child { border-right: 0; }
.result-strip small { display: block; color: var(--muted); font: 700 8px var(--mono); letter-spacing: 0.12em; }
.result-strip b { display: block; max-width: 100%; margin-top: 4px; overflow-wrap: anywhere; font: 900 clamp(16px, 2.1vw, 26px)/1.08 var(--mono); letter-spacing: -0.05em; }
.calc-status { min-height: 47px; margin: 0; padding: 13px 25px 16px; color: var(--muted); border-top: 1px solid var(--line); font: 650 11px var(--mono); text-align: center; }
.noscript { padding: 15px; color: #172033; background: var(--yellow); text-align: center; }

.guide-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.guide-card { position: relative; min-height: 260px; padding: 29px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); box-shadow: 0 12px 35px rgba(26, 35, 55, 0.04); }
.guide-card.featured { grid-column: span 2; color: #172033; background: var(--blue); border: 2px solid #172033; box-shadow: 6px 6px 0 #172033; }
.card-number { color: var(--muted); font: 750 9px var(--mono); }
.featured .card-number { color: rgba(23, 32, 51, 0.62); }
.guide-card h3 { margin: 45px 0 10px; font-size: 23px; }
.guide-card p { margin: 0; color: var(--muted); font-size: 14px; }
.featured p { max-width: 630px; color: rgba(23, 32, 51, 0.76); }
.mini-equation { display: inline-block; margin-top: 22px; padding: 8px 12px; color: #dfe9cf; background: #172033; border-radius: 9px; font: 700 11px var(--mono); }

.model-section { padding-block: 110px; background: #172033; color: #eff2f9; }
.model-layout { display: grid; grid-template-columns: 0.85fr 1.15fr; align-items: center; gap: 80px; }
.model-copy h2 { margin: 20px 0 24px; font-size: clamp(39px, 5vw, 67px); line-height: 1.08; letter-spacing: -0.055em; }
.model-copy > p:not(.kicker) { color: #aeb8ca; }
.force-stack { display: grid; gap: 13px; }
.force-card { display: flex; align-items: center; gap: 23px; padding: 23px 26px; color: #172033; border: 2px solid #080c14; border-radius: 24px; box-shadow: 6px 6px 0 #080c14; }
.force-card > span { display: grid; place-items: center; flex: 0 0 auto; width: 65px; height: 65px; color: #eff2f9; background: #172033; border-radius: 18px; font: 900 25px var(--mono); transform: rotate(-5deg); }
.force-card small { font: 750 8px var(--mono); letter-spacing: 0.12em; }
.force-card h3 { margin: 1px 0 0; font-size: 23px; }
.force-card p { margin: 1px 0 0; opacity: 0.7; font: 650 11px var(--mono); }
.force-card.gravity { background: var(--coral); transform: rotate(-1deg); }
.force-card.rolling { background: var(--lime); transform: rotate(1deg); }
.force-card.aero { background: var(--blue); transform: rotate(-0.5deg); }
.coefficient-strip { display: grid; grid-template-columns: repeat(4, 1fr); margin-top: 70px; border-block: 1px solid #39445a; }
.coefficient-strip div { padding: 23px; border-right: 1px solid #39445a; }
.coefficient-strip div:last-child { border-right: 0; }
.coefficient-strip small { display: block; color: #8e9ab0; font: 700 8px var(--mono); letter-spacing: 0.12em; }
.coefficient-strip b { display: block; margin: 4px 0; color: var(--lime); font: 900 22px var(--mono); }
.coefficient-strip span { color: #aeb8ca; font-size: 11px; }

.example-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; padding: 0; list-style: none; counter-reset: example; }
.example-list li { display: grid; grid-template-columns: auto 1fr; gap: 19px; min-height: 145px; padding: 24px; border: 1px solid var(--line); border-radius: 21px; background: var(--surface); counter-increment: example; }
.example-list li::before { content: "0" counter(example); color: var(--coral-dark); font: 850 12px var(--mono); }
.example-list b { display: block; margin-bottom: 7px; }
.example-list span { color: var(--muted); font-size: 13px; }

.about-section { padding: 20px 0 110px; }
.about-card { display: grid; grid-template-columns: 0.8fr 1.3fr; gap: 28px 55px; padding: 42px; color: #172033; background: var(--yellow); border: 2px solid #172033; border-radius: 32px; box-shadow: 8px 8px 0 #172033; }
.about-card small { font: 750 9px var(--mono); letter-spacing: 0.12em; }
.about-card h2 { margin: 10px 0 0; font-size: clamp(26px, 3vw, 39px); line-height: 1.15; }
.about-card > p { margin: 0; font-size: 14px; }
.privacy-note { grid-column: 2; display: flex; align-items: center; gap: 15px; padding-top: 20px; border-top: 1px solid rgba(23, 32, 51, 0.26); }
.privacy-note i { flex: 0 0 auto; }
.privacy-note b { display: block; }

.site-footer { display: flex; align-items: center; gap: 35px; min-height: 150px; padding: 32px max(24px, calc((100vw - 1180px) / 2)); color: #dce6ef; background: #161d24; }
.footer-brand { margin-right: auto; }
.site-footer p { margin: 0; color: #9ba6ba; font-size: 12px; }
.site-footer > a:last-child { color: var(--lime); font-size: 12px; font-weight: 750; }

@media (max-width: 1020px) {
  .page-nav { display: none; position: absolute; top: 77px; right: 20px; left: 20px; grid-template-columns: repeat(2, 1fr); gap: 6px; padding: 12px; background: var(--solid); border: 1px solid var(--line); border-radius: 18px; box-shadow: var(--shadow); }
  .page-nav.open { display: grid; }
  .menu-toggle { display: inline-grid; place-items: center; }
  .hero { grid-template-columns: 1fr; gap: 45px; }
  .hero-copy { padding-top: 20px; }
  .hero-visual { width: min(650px, 100%); min-height: 500px; margin-inline: auto; }
  #heroCanvas { min-height: 500px; }
  .field-grid { grid-template-columns: repeat(3, 1fr); }
  .field-grid > :nth-child(5n) { border-right: 1px solid var(--line); }
  .field-grid > :nth-child(3n) { border-right: 0; }
  .field-grid > :last-child { grid-column: span 3; border-right: 0; }
  .prediction-grid { grid-template-columns: repeat(3, 1fr); }
  .prediction-copy { grid-column: span 3; border-right: 0; border-bottom: 1px solid var(--line); }
  .model-layout { grid-template-columns: 1fr; gap: 45px; }
}

@media (max-width: 740px) {
  .shell { width: min(100% - 28px, 620px); }
  .site-header { height: 70px; padding-inline: 14px; gap: 12px; }
  .page-nav { top: 69px; right: 14px; left: 14px; }
  .brand small,
  .local-pill { display: none; }
  .header-actions { margin-left: auto; }
  .back-link { padding-inline: 11px; }
  .back-link span { display: none; }
  .hero { min-height: auto; padding-block: 65px 75px; }
  .hero h1 { font-size: clamp(42px, 13vw, 63px); }
  .hero-lead { font-size: 15px; }
  .hero-meta { justify-content: space-between; gap: 12px; }
  .hero-visual { min-height: 420px; }
  #heroCanvas { min-height: 420px; }
  .telemetry { min-width: 115px; padding: 9px 11px; }
  .telemetry-power { top: 38px; left: 18px; }
  .telemetry-speed { right: 17px; bottom: 51px; }
  .coordinate { display: none; }
  .calculator-section,
  .content-section,
  .model-section { padding-block: 78px; }
  .section-heading { display: block; }
  .section-heading > span { display: block; margin-top: 12px; text-align: left; }
  .calculator { border-radius: 24px; }
  .calc-primary { grid-template-columns: 1fr; }
  .direction-mark { width: 100%; height: 42px; border: 0; border-block: 1px solid var(--line); }
  .hero-field { padding: 25px 22px; }
  .range-row { padding: 18px 22px; }
  .conditions-head { align-items: stretch; padding: 24px 20px 16px; }
  .unit-select { width: 48%; }
  .field-grid { grid-template-columns: repeat(2, 1fr); }
  .field-grid > :nth-child(3n) { border-right: 1px solid var(--line); }
  .field-grid > :nth-child(2n) { border-right: 0; }
  .field-grid > :last-child { grid-column: span 2; }
  .prediction-grid { grid-template-columns: 1fr; }
  .prediction-copy { grid-column: auto; }
  .prediction-grid > label { border-right: 0; border-bottom: 1px solid var(--line); }
  .result-strip { grid-template-columns: repeat(2, 1fr); }
  .result-strip b { font-size: clamp(15px, 5vw, 22px); }
  .result-strip div:nth-child(2) { border-right: 0; }
  .result-strip div:nth-child(-n + 2) { border-bottom: 1px solid var(--line); }
  .guide-grid { grid-template-columns: 1fr; }
  .guide-card.featured { grid-column: auto; }
  .guide-card h3 { margin-top: 25px; }
  .coefficient-strip { grid-template-columns: repeat(2, 1fr); }
  .coefficient-strip div:nth-child(2) { border-right: 0; }
  .coefficient-strip div:nth-child(-n + 2) { border-bottom: 1px solid #39445a; }
  .example-list { grid-template-columns: 1fr; }
  .about-card { grid-template-columns: 1fr; padding: 28px; }
  .privacy-note { grid-column: auto; }
  .site-footer { flex-wrap: wrap; gap: 18px; padding: 32px 20px; }
  .footer-brand { width: 100%; }
}

@media (max-width: 440px) {
  .site-header .brand b { font-size: 12px; }
  .back-link { font-size: 11px; }
  .hero-actions { align-items: flex-start; flex-direction: column; }
  .hero-meta { font-size: 8px; }
  .hero-meta b { font-size: 14px; }
  .hero-visual { min-height: 360px; }
  #heroCanvas { min-height: 360px; }
  .telemetry b { font-size: 13px; }
  .conditions-head { flex-direction: column; }
  .unit-select { width: 100%; }
  .field-grid { grid-template-columns: 1fr; }
  .field-grid > :nth-child(n) { border-right: 0; }
  .field-grid > :last-child { grid-column: auto; }
  .result-strip { grid-template-columns: 1fr; }
  .result-strip b { font-size: clamp(16px, 7vw, 24px); }
  .result-strip div:nth-child(n) { border-right: 0; border-bottom: 1px solid var(--line); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after { scroll-behavior: auto !important; animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; }
}