:root {
  color-scheme: light dark;
  --workspace: #f5f5f3; --surface: #fcfcfb; --paper: #fefefd; --soft: #efefec;
  --ink: #252523; --secondary: #6b6b65; --line: #e6e6e1; --rule: #eeeee9;
  --accent: #0066cc; --accent-soft: #e8f1fc; --on-accent: #fff;
  --shadow: 0 16px 60px rgb(30 35 45 / 8%), 0 3px 12px rgb(30 35 45 / 4%);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI Variable Text", "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 16px; line-height: 1.65; color: var(--ink); background: var(--workspace);
  scrollbar-color: var(--secondary) var(--workspace); scroll-padding-top: 96px; scroll-behavior: smooth; -webkit-font-smoothing: antialiased;
}
* { box-sizing: border-box; }
body { margin: 0; }
[hidden] { display: none !important; }
.visually-hidden { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
h1, h2, h3, p { margin: 0; }
h1, h2, h3 { text-wrap: balance; }
p { text-wrap: pretty; }
::selection { background: var(--accent-soft); color: var(--ink); }
a { color: var(--accent); text-underline-offset: 4px; }
a:hover { text-decoration-thickness: 2px; }
button, input { font: inherit; }
button { cursor: pointer; }
button:disabled { cursor: default; opacity: .5; }
button, a, input { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 5px; border-radius: 4px; }
svg { fill: none; stroke: currentColor; stroke-width: 1.65; stroke-linecap: round; stroke-linejoin: round; flex: 0 0 auto; }
.wrap { width: min(100% - 64px, 1100px); margin-inline: auto; }
.site-header { position: sticky; top: 0; z-index: 10; background: var(--workspace); border-bottom: 1px solid var(--line); }
.header-inner { height: 76px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-size: 22px; font-weight: 650; letter-spacing: .08em; color: var(--ink); text-decoration: none; }
.brand img { display: block; }
.main-nav { display: flex; align-items: center; gap: 34px; margin-left: auto; margin-right: 16px; }
.main-nav a { color: var(--secondary); text-decoration: none; font-size: 14px; padding-block: 16px; }
.main-nav a:hover { color: var(--ink); }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 13px; min-height: 50px; padding: 12px 23px; border-radius: 12px; background: var(--accent); color: var(--on-accent); text-decoration: none; font-size: 16px; font-weight: 550; white-space: nowrap; transition: background-color 180ms ease-out, box-shadow 180ms ease-out; }
.button:hover { background: color-mix(in srgb, var(--accent) 88%, var(--ink)); }
.button:active { box-shadow: inset 0 0 0 2px var(--on-accent); }
.button svg { width: 18px; height: 18px; }
.button-small { min-height: 44px; padding: 9px 16px; font-size: 14px; gap: 10px; }
.hero { text-align: center; padding: 65px 0 35px; }
.hero h1 { font-size: clamp(42px, 4.6vw, 66px); font-weight: 650; line-height: 1.21; letter-spacing: -.035em; }
.hero h1 span { color: var(--secondary); }
.hero-description { margin-top: 25px; font-size: 19px; line-height: 1.7; color: var(--secondary); }
.mobile-break { display: none; }
.hero-actions { display: flex; align-items: center; justify-content: center; gap: 27px; margin-top: 27px; }
.text-link { display: inline-flex; align-items: center; gap: 10px; min-height: 44px; text-decoration: none; font-size: 16px; }
.text-link:hover { text-decoration: underline; }
.text-link svg { width: 20px; height: 20px; }
.availability { margin-top: 18px; font-size: 12px; color: var(--secondary); }
.experience { margin-top: 10px; }
.notebook { --demo-toolbar-height: 68px; position: relative; border-radius: 16px; background: var(--paper); box-shadow: var(--shadow); overflow: hidden; }
.demo-toolbar { display: flex; align-items: center; justify-content: center; height: var(--demo-toolbar-height); padding: 9px 20px; background: var(--surface); }
.demo-tabs { display: flex; background: var(--soft); border-radius: 12px; padding: 3px; }
.demo-tabs button { display: inline-flex; align-items: center; justify-content: center; gap: 8px; border: 0; background: transparent; color: var(--secondary); min-height: 44px; padding: 7px 17px; border-radius: 9px; font-size: 13px; font-weight: 500; transition: background-color 180ms ease-out, color 180ms ease-out, box-shadow 180ms ease-out; }
.demo-tabs svg { width: 18px; height: 18px; }
.demo-tabs button[aria-selected="true"] { color: var(--ink); background: var(--paper); box-shadow: 0 2px 5px rgb(0 0 0 / 6%); }
.demo-actions { position: absolute; z-index: 3; top: calc(var(--demo-toolbar-height) + max(12px, env(safe-area-inset-top))); right: max(16px, env(safe-area-inset-right)); display: flex; gap: 8px; }
.demo-tool, .icon-button { display: inline-flex; align-items: center; justify-content: center; gap: 7px; min-width: 44px; min-height: 44px; border: 0; border-radius: 12px; color: var(--ink); background: var(--soft); padding: 8px 12px; font-size: 13px; font-weight: 500; transition: background-color 180ms ease-out, color 180ms ease-out; }
.demo-tool svg, .icon-button svg { width: 19px; height: 19px; }
.demo-tool:hover, .icon-button:hover { background: var(--accent-soft); color: var(--accent); }
.demo-tool:active, .icon-button:active { background: var(--line); }
.demo-tool[aria-expanded="true"] { background: var(--accent-soft); color: var(--accent); }
.icon-button { padding: 8px; background: transparent; }
.lab-panel { position: relative; }
.lab-stage { position: relative; min-width: 0; height: clamp(380px, 58svh, 580px); overflow: hidden; }
#lab-canvas, #lab-fallback { display: block; width: 100%; height: 100%; position: absolute; inset: 0; }
#lab-canvas { cursor: grab; touch-action: none; }
#lab-canvas:active { cursor: grabbing; }
#lab-canvas:focus-visible { outline-offset: -5px; }
.model-label { position: absolute; z-index: 1; pointer-events: none; font-size: 12px; font-weight: 600; background: var(--paper); border: 1px solid var(--line); border-radius: 6px; padding: 1px 6px; transform: translate(-50%, -100%); }
.view-toolbar { display: flex; justify-content: space-between; align-items: center; gap: 8px; margin-top: 16px; }
.view-toolbar > span { font-size: 12px; color: var(--secondary); }
.view-actions { display: flex; align-items: center; gap: 2px; }
.view-actions button { border: 0; background: transparent; color: var(--secondary); min-width: 44px; min-height: 44px; padding: 5px 9px; border-radius: 9px; font-size: 12px; }
.view-actions button svg { width: 18px; height: 18px; vertical-align: middle; }
.view-actions button:hover { color: var(--accent); background: var(--accent-soft); }
.stage-legend { position: absolute; left: 24px; bottom: 20px; display: flex; gap: 16px; font-size: 12px; color: var(--secondary); pointer-events: none; }
.stage-legend span { display: inline-flex; align-items: center; gap: 6px; }
.stage-legend i { width: 8px; height: 8px; border-radius: 50%; background: #2476d6; }
.stage-legend .legend-high { background: #e8a450; }
.stage-legend .legend-center { background: var(--ink); width: 12px; height: 2px; border-radius: 0; }
.lab-controls { position: absolute; z-index: 4; top: 68px; right: 16px; width: min(316px, calc(100% - 32px)); max-height: calc(100% - 84px); padding: 12px 20px 20px; border-radius: 16px; background: var(--surface); box-shadow: var(--shadow); overflow-y: auto; overscroll-behavior: contain; scrollbar-width: thin; animation: settings-enter 180ms cubic-bezier(.16, 1, .3, 1); }
.settings-heading { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin-bottom: 12px; }
.settings-heading h2 { font-size: 16px; font-weight: 600; }
.settings-heading .icon-button { margin-right: -8px; }
@keyframes settings-enter { from { opacity: 0; transform: translateY(-6px); } to { opacity: 1; transform: translateY(0); } }
.experiment-presets { display: flex; gap: 6px; margin-bottom: 21px; }
.experiment-presets button { flex: 1; border: 1px solid var(--line); background: var(--paper); color: var(--secondary); border-radius: 9px; min-height: 44px; padding: 5px 7px; font-size: 12px; }
.experiment-presets button[aria-pressed="true"] { color: var(--accent); border-color: var(--accent); background: var(--accent-soft); }
.scene-controls label { display: flex; justify-content: space-between; align-items: center; gap: 8px; font-size: 13px; }
.scene-controls label output { color: var(--accent); font-variant-numeric: tabular-nums; font-weight: 550; }
input[type="range"] { display: block; width: 100%; height: 44px; margin: 0 0 10px; padding: 0; accent-color: var(--accent); cursor: pointer; }
.experiment-result { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; margin-top: 8px; padding-top: 12px; }
.experiment-result > span { display: block; color: var(--secondary); font-size: 12px; }
.experiment-result > output { display: block; font-size: 30px; line-height: 1.5; letter-spacing: -.035em; font-weight: 550; font-variant-numeric: tabular-nums; white-space: nowrap; }
.experiment-result small { font-size: 15px; letter-spacing: 0; font-weight: 400; color: var(--secondary); }
.model-assumption, .orbit-measures, .time-caption { font-size: 12px; line-height: 1.75; color: var(--secondary); }
.model-assumption { margin-top: 10px; }
.lab-observation { font-size: 13px; line-height: 1.8; margin-top: 17px; }
.experiment-actions { display: flex; align-items: center; gap: 15px; margin-bottom: 20px; }
.model-notes { margin-top: 12px; border: 0; font-size: 12px; color: var(--secondary); }
.model-notes summary { display: flex; align-items: center; min-height: 44px; padding-block: 8px; font-size: 13px; cursor: pointer; }
.model-notes summary::after { content: ''; width: 7px; height: 7px; margin-left: auto; border-right: 1.5px solid currentColor; border-bottom: 1.5px solid currentColor; transform: rotate(45deg); }
.model-notes[open] summary::after { transform: rotate(225deg); }
.play-button { display: inline-flex; align-items: center; justify-content: center; gap: 7px; min-height: 44px; padding: 8px 13px; border: 0; border-radius: 9px; background: var(--accent); color: var(--on-accent); font-size: 13px; font-weight: 550; }
.play-button svg { width: 16px; height: 16px; }
.time-caption { margin-top: 8px; }
.render-status { position: absolute; top: 72px; left: 24px; right: 24px; font-size: 12px; color: var(--secondary); }
.reset-button { display: inline-flex; align-items: center; justify-content: center; gap: 7px; background: transparent; border: 0; color: var(--secondary); min-height: 44px; padding: 5px 0; font-size: 12px; }
.reset-button:not(:disabled):hover { color: var(--accent); }
.reset-button svg { width: 15px; height: 15px; }
.ink-panel { position: relative; padding-inline: 24px; height: clamp(380px, 58svh, 580px); }
.ink-intro { position: absolute; bottom: 12px; right: 24px; z-index: 1; }
.ink-intro .reset-button { white-space: nowrap; }
.ink-paper { position: relative; height: 100%; background-image: repeating-linear-gradient(to bottom, transparent 0, transparent 35px, var(--rule) 35px, var(--rule) 36px); }
#ink-canvas { display: block; width: 100%; height: 100%; cursor: crosshair; touch-action: none; }
.ink-placeholder { pointer-events: none; position: absolute; inset: 45% 20px auto; text-align: center; color: var(--secondary); font-size: 24px; font-family: KaiTi, STKaiti, "Kaiti SC", serif; }
html.demo-expanded, html.demo-expanded body { overflow: hidden; }
.notebook.is-expanded { position: fixed; z-index: 100; inset: 0; width: 100%; height: 100dvh; display: flex; flex-direction: column; border-radius: 0; box-shadow: none; padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left); }
.notebook.is-expanded .demo-toolbar { flex-shrink: 0; }
.notebook.is-expanded .demo-panel { flex: 1; min-height: 0; }
.notebook.is-expanded .lab-stage { height: 100%; }
.experience-caption { margin-top: 20px; text-align: center; color: var(--secondary); font-size: 12px; }
.no-script { padding: 12px; color: var(--secondary); font-size: 14px; }
.essentials { display: grid; grid-template-columns: repeat(3, 1fr); gap: 60px; padding: 74px 15px 90px; }
.essentials > div > svg { display: block; width: 30px; height: 30px; color: var(--secondary); margin-bottom: 17px; }
.essentials h2 { font-size: 20px; font-weight: 600; letter-spacing: -.02em; }
.essentials p { font-size: 14px; color: var(--secondary); line-height: 1.9; margin-top: 12px; }
.workflow-section { background: var(--surface); }
.workflow { display: grid; grid-template-columns: 1fr 1fr; gap: 90px; padding-block: 94px 100px; }
.workflow-heading { align-self: center; }
.workflow-heading h2, .section-heading h2 { font-size: clamp(32px, 3vw, 42px); font-weight: 600; line-height: 1.3; letter-spacing: -.03em; }
.workflow-heading > p { margin-top: 22px; color: var(--secondary); font-size: 17px; line-height: 1.9; }
.workflow-heading .text-link { margin-top: 25px; font-size: 14px; }
.workflow-steps { list-style: none; padding: 0; margin: 0; }
.workflow-steps li { display: flex; align-items: flex-start; gap: 19px; padding-block: 26px; border-top: 1px solid var(--line); }
.workflow-steps li:first-child { padding-top: 0; border: 0; }
.workflow-steps li:last-child { padding-bottom: 0; }
.step-number { display: flex; align-items: center; justify-content: center; width: 28px; height: 28px; flex: 0 0 28px; margin-top: 2px; background: var(--soft); color: var(--secondary); font-size: 13px; font-variant-numeric: tabular-nums; border-radius: 50%; }
.workflow-steps h3 { font-size: 18px; font-weight: 600; letter-spacing: -.02em; }
.workflow-steps p { font-size: 14px; margin-top: 9px; color: var(--secondary); line-height: 1.85; }
.workflow-steps .workflow-note { font-size: 12px; }
.download-section { padding-top: 94px; }
.section-heading { text-align: center; }
.section-heading > p { margin-top: 17px; font-size: 17px; color: var(--secondary); }
.downloads { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin-top: 44px; align-items: start; }
.release { padding: 32px 34px 0; background: var(--surface); border-radius: 16px; }
.platform-icon { width: 48px; height: 48px; color: var(--secondary); margin-bottom: 18px; }
.release h3 { font-size: 27px; font-weight: 600; letter-spacing: -.025em; }
.platform-description { font-size: 15px; color: var(--secondary); margin-top: 9px; }
.requirements { font-size: 12px; color: var(--secondary); margin-top: 20px; }
.download-button { width: 100%; margin-top: 20px; min-height: 48px; font-size: 15px; }
.release-meta { margin-block: 13px 22px; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 3px 14px; color: var(--secondary); font-size: 12px; font-variant-numeric: tabular-nums; }
details { border-top: 1px solid var(--line); }
summary { display: flex; justify-content: space-between; align-items: center; gap: 16px; min-height: 62px; padding-block: 17px; font-size: 14px; cursor: pointer; list-style: none; }
summary::-webkit-details-marker { display: none; }
summary svg { width: 20px; height: 20px; color: var(--secondary); transition: transform 180ms cubic-bezier(.16, 1, .3, 1); }
details[open] > summary svg { transform: rotate(180deg); }
summary:hover { color: var(--accent); }
.detail-body { max-width: 72ch; padding-bottom: 24px; font-size: 14px; line-height: 1.9; color: var(--secondary); overflow-wrap: anywhere; }
.detail-body p + p, .detail-body ol + p { margin-top: 12px; }
.detail-body ol { margin: 2px 0 0; padding-left: 1.5em; }
.detail-body li + li { margin-top: 6px; }
.download-note { display: flex; align-items: center; justify-content: center; gap: 9px; margin-top: 24px; font-size: 12px; color: var(--secondary); }
.download-note svg { width: 17px; height: 17px; }
.github-support { display: flex; align-items: center; justify-content: space-between; gap: 40px; margin-top: 42px; padding-top: 34px; border-top: 1px solid var(--line); }
.github-copy { max-width: 560px; }
.github-copy h3 { font-size: 36px; font-weight: 650; line-height: 1.3; letter-spacing: -.025em; }
.github-copy p { margin-top: 16px; font-size: 16px; line-height: 1.85; color: var(--secondary); }
.github-actions { flex: 0 0 auto; text-align: center; }
.github-button { border: 1px solid var(--line); background: var(--surface); color: var(--ink); font-size: 16px; min-height: 50px; }
.github-button:hover { background: var(--soft); }
.github-button:active { box-shadow: inset 0 0 0 1px var(--secondary); }
.help { display: grid; grid-template-columns: .9fr 1.4fr; gap: 80px; padding-block: 104px 86px; }
.help-heading h2 { font-size: 30px; font-weight: 600; line-height: 1.45; letter-spacing: -.025em; }
.help-heading p { font-size: 14px; line-height: 1.9; margin-top: 20px; color: var(--secondary); }
.questions { border-bottom: 1px solid var(--line); }
.questions summary { font-size: 15px; min-height: 66px; }
dl { margin: 18px 0; }
dt { color: var(--ink); font-weight: 600; margin-top: 14px; }
dd { margin: 4px 0 0; }
code { font-family: ui-monospace, Consolas, monospace; font-size: 12px; overflow-wrap: anywhere; }
.site-footer { border-top: 1px solid var(--line); display: flex; justify-content: space-between; align-items: center; gap: 24px; padding-block: 36px 42px; color: var(--secondary); }
.site-footer .brand { font-size: 19px; gap: 8px; }
.site-footer p { font-size: 12px; margin-top: 10px; }
.site-footer nav { display: flex; gap: 26px; align-items: center; font-size: 12px; }
.site-footer a { color: var(--secondary); }
.site-footer nav a { padding-block: 12px; }
.skip-link { position: fixed; top: -80px; left: 20px; padding: 12px 20px; z-index: 20; background: var(--surface); }
.skip-link:focus { top: 12px; }
.policy { max-width: 760px; padding-top: 48px; padding-bottom: 40px; }
.policy h1 { font-size: 34px; font-weight: 650; line-height: 1.4; }
.policy .policy-meta { margin-top: 20px; color: var(--secondary); font-size: 14px; }
.policy h2 { font-size: 20px; line-height: 1.5; margin: 36px 0 14px; }
.policy p { line-height: 1.9; overflow-wrap: anywhere; }
.policy section p + p { margin-top: 16px; }
.site-header.wrap { position: static; height: 76px; display: flex; align-items: center; justify-content: space-between; gap: 20px; }
@media (prefers-color-scheme: dark) {
  :root { --workspace: #0b0b0a; --surface: #151515; --paper: #1a1a19; --soft: #20201e; --ink: #e9e9e4; --secondary: #a5a59d; --line: #30302c; --rule: #30302c; --accent: #78b7ff; --accent-soft: #203247; --on-accent: #10273e; --shadow: 0 16px 60px rgb(0 0 0 / 25%); }
  .hero h1 { font-weight: 610; }
}
@media (max-width: 900px) {
  .main-nav { gap: 22px; }
  .hero { padding-top: 50px; }
  .essentials { gap: 32px; padding-inline: 0; }
  .workflow { gap: 55px; }
  .help { gap: 48px; }
  .release { padding-inline: 25px; }
}
@media (max-width: 700px) {
  :root { scroll-padding-top: 88px; }
  .wrap { width: calc(100% - 40px); }
  .header-inner { height: 68px; gap: 16px; }
  .brand { font-size: 20px; gap: 8px; }
  .brand img { width: 26px; height: 26px; }
  .main-nav { display: none; }
  .button-small { font-size: 13px; padding-inline: 13px; }
  .hero { padding-top: 48px; padding-bottom: 29px; }
  .hero h1 { font-size: clamp(33px, 8.6vw, 48px); line-height: 1.3; letter-spacing: -.035em; }
  .hero-description { font-size: 16px; margin-top: 22px; line-height: 1.85; }
  .mobile-break { display: initial; }
  .hero-actions { gap: 23px; margin-top: 23px; }
  .hero-actions .button { font-size: 14px; min-height: 48px; padding-inline: 18px; gap: 9px; }
  .text-link { font-size: 14px; gap: 7px; }
  .availability { font-size: 12px; margin-top: 18px; }
  .experience { width: calc(100% - 32px); }
  .demo-toolbar { padding-inline: 12px; }
  .demo-tabs { flex: 1; }
  .demo-tabs button { flex: 1; flex-direction: column; padding: 7px 4px; gap: 4px; font-size: 12px; min-width: 0; }
  .demo-tool { padding: 8px; }
  .demo-tool > span { display: none; }
  .lab-controls { top: auto; bottom: 16px; max-height: min(52%, 360px); }
  .stage-legend { left: 20px; top: 26px; bottom: auto; }
  .experiment-presets { margin-bottom: 19px; }
  .model-assumption { margin-top: 7px; }
  .lab-observation { margin-top: 13px; }
  .render-status { left: 20px; }
  .experience-caption { padding-inline: 13px; font-size: 12px; line-height: 1.8; }
  .ink-panel { padding-inline: 20px; }
  .ink-placeholder { font-size: 22px; }
  .essentials { grid-template-columns: 1fr; gap: 0; padding-block: 42px 53px; }
  .essentials > div { position: relative; padding: 23px 0 23px 49px; }
  .essentials > div > svg { position: absolute; left: 0; top: 26px; width: 26px; height: 26px; }
  .essentials h2 { font-size: 18px; }
  .essentials p { font-size: 14px; margin-top: 9px; }
  .workflow { grid-template-columns: 1fr; gap: 38px; padding-block: 58px 61px; }
  .workflow-heading h2, .section-heading h2 { font-size: 32px; }
  .workflow-heading > p { font-size: 16px; margin-top: 19px; }
  .workflow-heading .text-link { margin-top: 15px; }
  .workflow-steps li { gap: 15px; }
  .workflow-steps h3 { font-size: 17px; }
  .workflow-steps p { font-size: 14px; }
  .download-section { padding-top: 58px; }
  .section-heading h2 { font-size: 29px; }
  .section-heading > p { font-size: 15px; margin-top: 14px; }
  .downloads { grid-template-columns: 1fr; gap: 20px; margin-top: 30px; }
  .release { padding: 26px 24px 0; }
  .platform-icon { width: 40px; height: 40px; margin-bottom: 16px; }
  .release h3 { font-size: 25px; }
  .platform-description { font-size: 14px; }
  .release-meta { font-size: 12px; margin-bottom: 18px; }
  .requirements { margin-top: 18px; }
  .download-note { font-size: 12px; gap: 6px; flex-wrap: wrap; }
  .download-note svg { width: 15px; height: 15px; }
  .github-support { align-items: flex-start; flex-direction: column; gap: 22px; margin-top: 32px; padding-top: 28px; }
  .github-copy h3 { font-size: 30px; }
  .github-actions { text-align: left; }
  .help { grid-template-columns: 1fr; gap: 30px; padding-block: 64px 52px; }
  .help-heading h2 { font-size: 28px; }
  .help-heading p { font-size: 13px; margin-top: 16px; }
  .questions summary { font-size: 14px; }
  .site-footer { align-items: start; flex-direction: column; padding-block: 28px 30px; gap: 21px; }
  .site-footer nav { flex-wrap: wrap; gap: 8px 23px; font-size: 12px; }
  .site-footer .brand img { width: 23px; height: 23px; }
  .policy { padding-top: 32px; }
  .policy h1 { font-size: 28px; }
  .site-header.wrap { height: 68px; }
}
@media (prefers-reduced-motion: reduce) {
  :root { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
}
@media (forced-colors: active) {
  :focus-visible { outline: 3px solid Highlight; }
  .button, .demo-tabs button[aria-selected="true"] { border: 1px solid ButtonText; }
}