@charset "UTF-8";
@import url("./design/design-system.css");

:root {
  --paper: #f5f4ef;
  --panel: #fff;
  --ink: #232522;
  --muted: #62645d;
  --line: #d7d6ce;
  --accent: #c21f3a;
  --radius: 0;
  --page-gutter: 80px;
  --nav-height: 80px;
}
* { box-sizing: border-box; }
html { scroll-behavior: auto; scroll-padding-top: 0; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 400 16px/1.75 var(--font-text, "PingFang SC", "Microsoft YaHei", sans-serif); -webkit-font-smoothing: antialiased; }
a { color: inherit; text-decoration: none; }
button, input { font: inherit; }
button { cursor: pointer; }
img { max-width: 100%; }
button, a, input, summary { -webkit-tap-highlight-color: transparent; }
:is(button, a, input, summary):focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; }
[hidden] { display: none !important; }
.skip-link { position: fixed; top: -80px; left: 20px; z-index: 200; padding: 10px 16px; background: var(--accent); color: #fff; border-radius: 0; }
.skip-link:focus { top: 10px; }
.page-width { width: min(calc(100% - 2 * var(--page-gutter)), 1280px); margin-inline: auto; }
.project-home :is(#main, #experiment, #learn, #resources, #purchase) { scroll-margin-top: 80px; }
.topbar { position: sticky; top: 0; z-index: 30; display: flex; align-items: center; justify-content: space-between; gap: 24px; min-height: var(--nav-height); width: min(calc(100% - 2 * var(--page-gutter)), 1280px); margin: auto; padding-block: 16px; background: var(--paper); border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; gap: 13px; align-items: center; flex-shrink: 0; font-size: 16px; font-weight: 500; line-height: 1.2; }
.brand-mark { display: block; width: 64px; height: 31px; object-fit: contain; flex-shrink: 0; }
.brand small { display: block; margin-top: 7px; color: var(--muted); font-size: 13px; font-weight: 400; letter-spacing: .02em; }
.topbar nav { display: flex; align-items: center; gap: 32px; font-size: 14px; }
.topbar nav a { display: inline-flex; align-items: center; min-height: 44px; padding: 8px 0; }
.topbar nav a:hover { color: var(--accent); }
.topbar nav a:last-child { padding: 7px 0; border-bottom: 1px solid var(--ink); }
.eyebrow { margin: 0 0 17px; color: var(--muted); font-size: 13px; letter-spacing: .08em; }
.status-dot { display: inline-block; width: 5px; height: 5px; margin-right: 7px; border-radius: 50%; background: var(--accent); vertical-align: 2px; }
.hero { display: grid; grid-template-columns: minmax(0, .86fr) minmax(0, 1.14fr); gap: 64px; align-items: center; min-height: calc(100svh - var(--nav-height)); padding-block: 64px; }
.hero h1 { margin: 0 0 24px; font-family: var(--font-display, var(--font-text)); font-size: clamp(40px, 4.1vw, 64px); line-height: 1.32; font-weight: 500; letter-spacing: -.04em; }
.hero h1 span { color: var(--accent); }
.hero-intro { margin: 0 0 27px; font-size: 17px; line-height: 1.9; color: var(--ink); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.button { display: inline-flex; align-items: center; justify-content: space-between; gap: 24px; min-height: 48px; padding: 12px 20px; font-size: 15px; border: 1px solid transparent; border-radius: 0; transition: background .15s, border-color .15s; }
.primary { color: #fff; background: var(--accent); border-color: var(--accent); }
.primary:hover { background: #a91831; border-color: #a91831; }
.quiet { color: var(--ink); border-color: var(--line); background: transparent; }
.quiet:hover { background: var(--panel); }
.project-specs { display: flex; flex-wrap: wrap; gap: 0; margin-top: 32px; color: var(--muted); font: 13px/1.5 var(--font-mono, Consolas, monospace); }
.project-specs span + span::before { content: "/"; margin: 0 13px; color: #c0c3c6; }
.hero-product { min-width: 0; margin: 0; }
.hero-product a { display: block; overflow: hidden; }
.hero-product img { display: block; width: 100%; height: auto; aspect-ratio: 4 / 3; object-fit: cover; }
.learning-layout { display: grid; grid-template-columns: minmax(0, .86fr) minmax(0, 1.14fr); gap: 64px; align-items: start; }
.hero-model { min-width: 0; margin: 0; overflow: hidden; background: #eaeae4; }
.model-top, .hero-model figcaption { display: flex; justify-content: space-between; gap: 12px; align-items: center; padding: 15px 20px; font-size: 13px; color: #717781; }
.model-top { border-bottom: 1px solid var(--line); padding-block: 12px; }
.model-top > span { color: #4d5661; font-size: 13px; }
.preview-tabs { display: flex; gap: 3px; }
.preview-tabs button { font-size: 13px; padding: 5px 11px; color: #797f87; border: 1px solid transparent; border-radius: 0; background: transparent; }
.preview-tabs button[aria-pressed=true] { color: var(--ink); background: transparent; border-bottom-color: var(--accent); }
.model-stage { display: block; height: 360px; overflow: hidden; }
.model-stage img { display: block; width: 100%; height: 100%; object-fit: contain; transition: transform .3s ease; }
.model-stage:hover img { transform: scale(1.025); }
.hero-model figcaption { border-top: 1px solid var(--line); }
.hero-model figcaption a { color: var(--ink); }
.hero-model figcaption a:hover { color: var(--accent); }

/* Keep the signal view visible on the landing page. */
.experiment-section { padding-block: 80px 48px; color: #f5f4ef; background: #202322; scroll-margin-top: 79px; }
.experiment-heading { display: flex; align-items: center; justify-content: space-between; gap: 25px; }
.experiment-section .eyebrow { color: #929ba9; margin-bottom: 10px; }
h2 { font-family: var(--font-display, var(--font-text)); font-size: 36px; font-weight: 500; line-height: 1.45; letter-spacing: -.035em; margin: 0; }
.mode-tabs { display: inline-flex; gap: 12px; padding: 0; border-bottom: 1px solid #444954; background: transparent; }
.mode-tabs button { padding: 10px 15px; border: 0; border-bottom: 1px solid transparent; margin-bottom: -1px; border-radius: 0; background: transparent; color: #a7afba; font-size: 13px; }
.mode-tabs button.active { color: #fff; background: transparent; border-bottom-color: #e27b8c; }
.experiment-grid { display: grid; grid-template-columns: 1.1fr 1fr; gap: 48px; margin-top: 48px; }
.sim-main, .sim-readout { min-width: 0; }
.sim-main > svg { display: block; width: 100%; background: #222529; border: 1px solid #3b3f44; border-radius: 0; }
.slider-label { display: flex; justify-content: space-between; align-items: center; margin: 18px 0 4px; font-size: 13px; color: #b7bec8; }
.slider-label output { color: #f7b5c1; font: 13px/1.7 Consolas, monospace; }
input[type=range] { width: 100%; margin: 5px 0; accent-color: #e06e83; cursor: pointer; }
.range-ticks { display: flex; justify-content: space-between; color: #939ca9; font-size: 13px; }
.sim-controls { display: flex; gap: 8px; align-items: center; margin-top: 14px; }
.sim-controls button { padding: 5px 11px; font-size: 13px; border: 1px solid #4c5461; border-radius: 0; color: #dce1e8; background: transparent; }
.sim-controls button[aria-pressed=true] { background: #783143; border-color: #ba6579; }
.sim-controls > span { margin-left: auto; color: #8f98a5; font-size: 13px; }
.sim-readout { padding-left: 30px; border-left: 1px solid #3c424c; }
.readout-top { display: flex; justify-content: space-between; align-items: center; gap: 15px; }
.readout-caption { margin: 0; font-size: 13px; color: #a5aebc; }
.big-readout { font: 43px/1.25 Consolas, monospace; letter-spacing: -.05em; margin: 5px 0 0; color: #f3b0bc; }
.big-readout small { font-size: 14px; color: #c1c8d2; margin-left: 10px; letter-spacing: 0; }
.si-readout { display: flex; flex-direction: column; align-items: flex-end; gap: 6px; font-size: 13px; color: #929caa; }
.si-readout code { color: #dee3eb; font-size: 13px; }
.sim-readout > svg { display: block; width: 100%; margin-top: 9px; }
.chart-legend { display: flex; justify-content: center; gap: 24px; color: #c5ccd6; font-size: 13px; }
.chart-legend span::before { content: ""; display: inline-block; width: 12px; height: 2px; margin-right: 6px; vertical-align: 3px; }
.u1::before { background: #f28d9a; }.u2::before { background: #7bc9d6; }.u4::before { background: #e1b76b; }
#mode-explanation { color: #a5afbd; font-size: 13px; margin: 13px 0 0; line-height: 1.8; }
.experiment-foot { display: flex; justify-content: space-between; gap: 20px; align-items: center; border-top: 1px solid #3a414c; margin-top: 25px; padding-top: 17px; font-size: 13px; }
.experiment-foot p { margin: 0; color: #909ba9; }
.experiment-foot a { color: #e7c6ce; flex-shrink: 0; }

.section { padding-block: 96px; }
.section-heading { display: flex; align-items: flex-end; justify-content: space-between; gap: 32px; margin-bottom: 48px; }
.section-heading .eyebrow { margin-bottom: 10px; }
.text-link { font-size: 14px; color: var(--muted); white-space: nowrap; }
.text-link:hover { color: var(--accent); }
.learning-steps { display: grid; grid-template-columns: 1fr; padding: 0; margin: 0; gap: 0; list-style: none; }
.learning-steps li { min-width: 0; padding: 20px 0 20px 52px; border-top: 1px solid var(--line); position: relative; }
.step-number { position: absolute; top: 23px; left: 0; color: var(--accent); font: 16px/1.5 var(--font-mono, Consolas, monospace); }
h3 { font-weight: 500; line-height: 1.6; font-size: 18px; margin: 0; }
.learning-steps h3 a { display: flex; justify-content: space-between; gap: 9px; }
.learning-steps h3 a span { font-size: 13px; color: #8e959e; }
.learning-steps h3 a:hover { color: var(--accent); }
.learning-steps p { font-size: 15px; color: var(--muted); line-height: 1.75; margin: 8px 0 0; }
.step-links { display: flex; flex-wrap: wrap; gap: 11px; margin-top: 12px; font-size: 13px; color: var(--accent); }
.step-links a { border-bottom: 1px solid #d4a8b0; padding-bottom: 2px; }
.quick-start { display: flex; justify-content: space-between; gap: 20px; align-items: center; padding-top: 25px; margin-top: 28px; border-top: 1px solid var(--line); font-size: 13px; color: var(--muted); }
.quick-start p { margin: 0; }.quick-start p a { color: var(--ink); text-decoration: underline; text-underline-offset: 4px; margin-inline: 4px; }
.quick-start > a { color: var(--accent); }
.resources-section { background: #eaeae3; padding-block: 80px; }
.resource-grid { display: grid; grid-template-columns: minmax(0, .86fr) minmax(0, 1.14fr); gap: 64px; }
.resource-card { display: flex; flex-direction: column; background: transparent; border-radius: 0; overflow: hidden; min-width: 0; }
.drawing-resource > img { width: 100%; height: 240px; object-fit: contain; padding: 24px; background: #fff; }
.drawing-resource > div { display: flex; flex-direction: column; justify-content: center; padding: 24px 0 0; }
.resource-kind { color: var(--muted); font-size: 13px; }
.drawing-resource h3 { margin-top: 8px; font-size: 20px; }
.drawing-resource h3 span { color: var(--muted); font-size: 13px; }
.drawing-resource p { margin: 8px 0 0; font-size: 15px; color: var(--muted); }
.resource-card:hover h3 { color: var(--accent); }
.resource-stack { display: flex; flex-direction: column; }
.resource-row { display: grid; grid-template-columns: 80px 1fr 20px; gap: 16px; align-items: center; padding: 28px 0; border-top: 1px solid #d0d4d1; }
.resource-row:last-child { border-bottom: 1px solid #d0d4d1; }
.resource-row h3 { font-size: 18px; }
.row-arrow { font-size: 13px; color: var(--muted); text-align: right; }
.resource-row:hover h3, .resource-row:hover .row-arrow { color: var(--accent); }
#purchase { padding-bottom: 0; }
.purchase-card { display: flex; align-items: center; justify-content: space-between; gap: 24px; padding: 32px 0; border-block: 1px solid var(--line); background: transparent; }
.purchase-card .eyebrow { color: var(--accent); margin-bottom: 10px; }
.purchase-card h2 + p { margin: 16px 0 0; max-width: 36em; color: var(--muted); font-size: 16px; }
.purchase-action { display: flex; align-items: center; gap: 20px; flex-shrink: 0; }
.purchase-price { margin: 0; white-space: nowrap; color: var(--muted); font-size: 13px; }
.purchase-price strong { color: var(--ink); font-size: 36px; font-weight: 500; line-height: 1; font-variant-numeric: tabular-nums; }
.project-note { display: flex; justify-content: space-between; gap: 22px; font-size: 13px; color: var(--muted); padding-block: 25px; }
.project-note p { margin: 0; }.project-note a { color: var(--muted); white-space: nowrap; }
.site-footer { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: 25px; padding-block: 28px 35px; border-top: 1px solid var(--line); }
.site-footer .site-filing { flex-basis: 100%; margin: 0; color: var(--muted); font-size: 12px; }
.site-footer > div { display: flex; gap: 26px; font-size: 13px; color: var(--muted); }
.site-footer a:hover { color: var(--accent); }

/* Shared document images, media and source browser. */
.figure-zoom { display: block; position: relative; width: 100%; background: #fff; color: var(--ink); border: 1px solid var(--line); border-radius: 0; padding: 10px; margin: 22px 0; cursor: zoom-in; }
.figure-zoom img { display: block; width: auto; max-width: 100%; margin: auto; }
.figure-zoom-label { position: absolute; right: 8px; bottom: 6px; padding: 2px 7px; border-radius: 0; background: #ffffffed; color: var(--muted); font-size: 13px; }
.figure-dialog { width: min(1100px, 94vw); max-width: 94vw; max-height: 94dvh; padding: 0; border: 1px solid #c8cdd1; border-radius: 0; background: #fff; color: var(--ink); }
.figure-dialog::backdrop { background: #15191fc2; }
.figure-dialog-head { display: flex; justify-content: space-between; align-items: center; gap: 15px; padding: 13px 17px; border-bottom: 1px solid var(--line); }
.figure-dialog-head p { font-size: 13px; line-height: 1.6; margin: 0; }
.figure-dialog-actions { display: flex; gap: 7px; flex-shrink: 0; }
.figure-dialog button { border: 1px solid var(--line); border-radius: 0; padding: 5px 9px; background: #f6f7f5; color: #4d5866; font-size: 13px; }
.figure-dialog-body { max-height: calc(94dvh - 65px); padding: 20px; overflow: auto; }
.figure-dialog-body img { display: block; max-width: none; height: auto; margin: auto; }
.source-topbar { max-width: none; }.source-topbar > a:last-child { font-size: 13px; color: var(--accent); }
.code-source { max-width: calc(100% - 48px); background: #fff; margin: 24px; padding: 23px; overflow: auto; border: 1px solid var(--line); border-radius: 0; font: 13px/1.7 var(--font-mono, Consolas, monospace); white-space: pre; }
.code-line { display: block; min-height: 20px; scroll-margin-top: 96px; }.line-number { display: inline-block; width: 45px; color: #a1a9b3; user-select: none; text-decoration: none; }
.code-line:target { background: #f9e5e9; }
.prototype-section:has(.prototype-empty) { display: none; }
.prototype-empty { border: 1px solid var(--line); padding: 22px; border-radius: 0; background: #f0f1ee; color: var(--muted); font-size: 13px; }
.prototype-empty span { color: var(--accent); font-weight: 600; }.prototype-empty p { margin: 7px 0 0; }
.prototype-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }
.prototype-pair { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 32px; }
.prototype-card { margin: 0; border-bottom: 1px solid var(--line); overflow: hidden; background: transparent; min-width: 0; }
.prototype-card img, .prototype-card video { width: 100%; height: auto; aspect-ratio: 4/3; display: block; object-fit: contain; background: #eeefec; }
.prototype-card figcaption { display: flex; flex-direction: column; gap: 4px; padding: 17px 0; font-size: 15px; line-height: 1.75; color: var(--muted); }
.prototype-card figcaption strong { color: var(--ink); font-size: 18px; font-weight: 500; }
.wiki-article .prototype-card img { margin: 0; }
.lesson-video { display: block; width: 100%; aspect-ratio: 16/9; height: auto; background: #17191e; border: 1px solid var(--line); border-radius: 0; }

@media (max-width: 1279px) {
  :root { --page-gutter: 48px; }
  .hero, .learning-layout, .resource-grid { gap: 40px; }
  .hero h1 { font-size: 48px; }
  .topbar nav { gap: 24px; }
}
@media (max-width: 1023px) {
  .hero { grid-template-columns: 1fr 1fr; gap: 32px; }
  .hero h1 { font-size: 40px; }
  .hero-intro { font-size: 16px; }
  .hero-actions { gap: 8px; }
  .hero-actions .button { padding-inline: 14px; font-size: 14px; gap: 16px; }
  .learning-layout { grid-template-columns: 1fr; }
  .learning-steps { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 32px; }
  .model-stage { height: 400px; }
  .experiment-grid { gap: 32px; }
  .sim-readout { padding-left: 24px; }
  .big-readout { font-size: 36px; }
  .resource-grid { gap: 32px; }
  .resource-row { grid-template-columns: 1fr 20px; gap: 8px; padding-block: 24px; }
  .resource-row .resource-kind { grid-column: 1; }
  .resource-row h3 { grid-column: 1; }
  .resource-row .row-arrow { grid-column: 2; grid-row: 1/3; }
}
@media (max-width: 767px) {
  :root { --page-gutter: 24px; --nav-height: 72px; }
  .project-home :is(#experiment, #learn, #resources, #purchase) { scroll-margin-top: 72px; }
  .topbar { gap: 12px; padding-block: 12px; }
  .brand { gap: 10px; font-size: 14px; }
  .brand-mark { width: 48px; height: 28px; }
  .brand small { font-size: 12px; margin-top: 5px; }
  .topbar nav { gap: 16px; font-size: 13px; }
  .topbar nav a[href="#learn"], .topbar nav a[href="#purchase"] { display: none; }
  .project-home .topbar nav a[href="#experiment"] { display: none; }
  .hero { grid-template-columns: 1fr; gap: 32px; padding-block: 40px; align-content: center; }
  .hero h1 { font-size: clamp(34px, 8.4vw, 44px); margin-bottom: 20px; }
  .hero .eyebrow { margin-bottom: 16px; }
  .hero-intro { font-size: 16px; margin-bottom: 24px; }
  .hero-actions { gap: 12px; }
  .hero-actions .button { font-size: 14px; padding: 12px 16px; gap: 18px; }
  .project-specs { margin-top: 24px; font-size: 13px; }
  .hero-product img { max-height: 300px; object-fit: cover; }
  h2 { font-size: 28px; }
  .experiment-section { padding-block: 64px 32px; }
  .experiment-heading { align-items: flex-start; flex-direction: column; gap: 24px; }
  .mode-tabs { align-self: stretch; }
  .mode-tabs button { flex: 1; min-height: 44px; font-size: 14px; }
  .experiment-grid { grid-template-columns: 1fr; margin-top: 32px; gap: 32px; }
  .sim-readout { padding: 24px 0 0; border-left: 0; border-top: 1px solid #3e4652; }
  .sim-readout > svg { max-height: 240px; }
  .big-readout { font-size: 38px; }
  .readout-caption, .si-readout, .si-readout code { font-size: 13px; }
  .sim-controls { flex-wrap: wrap; }
  .sim-controls button { min-height: 40px; padding: 7px 12px; }
  .sim-controls > span { flex-basis: 100%; margin: 0; }
  .experiment-foot { flex-direction: column; align-items: flex-start; gap: 12px; font-size: 13px; }
  .section { padding-block: 64px; }
  .section-heading { flex-wrap: wrap; align-items: flex-start; gap: 20px; margin-bottom: 32px; }
  .text-link { font-size: 13px; }
  .learning-layout { gap: 32px; }
  .learning-steps { grid-template-columns: 1fr; gap: 0; }
  .learning-steps li { padding: 20px 0 20px 44px; }
  .step-number { top: 22px; font-size: 15px; }
  .learning-steps h3 { font-size: 18px; }
  .learning-steps p { font-size: 15px; }
  .step-links { gap: 16px; font-size: 13px; }
  .model-stage { height: 300px; }
  .model-top, .hero-model figcaption { padding: 16px; font-size: 13px; flex-wrap: wrap; }
  .preview-tabs button { min-height: 40px; padding: 6px 12px; font-size: 13px; }
  .quick-start { align-items: flex-start; flex-direction: column; gap: 12px; font-size: 14px; margin-top: 32px; padding-top: 24px; }
  .resources-section { padding-block: 64px; }
  .resource-grid { grid-template-columns: 1fr; gap: 32px; }
  .drawing-resource > img { height: 240px; }
  .drawing-resource h3 { font-size: 20px; }
  .drawing-resource p { font-size: 15px; }
  .resource-kind { font-size: 13px; }
  .resource-row { grid-template-columns: 72px 1fr 16px; gap: 16px; padding-block: 24px; }
  .resource-row .resource-kind { grid-column: 1; }
  .resource-row h3 { grid-column: 2; font-size: 16px; }
  .resource-row .row-arrow { grid-column: 3; grid-row: 1; }
  .purchase-card { flex-direction: column; align-items: stretch; gap: 24px; padding-block: 32px; }
  .purchase-action { justify-content: space-between; gap: 16px; }
  .purchase-price strong { font-size: 32px; }
  .prototype-pair, .prototype-grid { grid-template-columns: 1fr; gap: 32px; }
  .prototype-card figcaption { padding-block: 16px; }
  .project-note { flex-direction: column; gap: 12px; font-size: 13px; padding-block: 24px; }
  .site-footer { align-items: flex-start; gap: 24px; padding-block: 32px; }
  .site-footer > div { flex-wrap: wrap; gap: 16px; max-width: 148px; justify-content: flex-end; font-size: 13px; }
  .figure-dialog-head { flex-direction: column; align-items: flex-start; gap: 12px; padding: 16px; }
  .figure-dialog-body { padding: 12px; max-height: calc(94dvh - 120px); }
  .code-source { margin: 16px; max-width: calc(100% - 32px); padding: 16px; font-size: 13px; }
}
@media (max-width: 359px) {
  .brand small { display: none; }
  .project-home .topbar nav a[href="#experiment"] { display: none; }
  .topbar nav { gap: 12px; }
  .hero-actions .button { padding-inline: 12px; gap: 12px; }
  .resource-row { grid-template-columns: 1fr 16px; gap: 8px; }
  .resource-row .resource-kind, .resource-row h3 { grid-column: 1; }
  .resource-row .row-arrow { grid-column: 2; grid-row: 1/3; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: 0s !important; }
}

/* Flat surfaces and shared editorial rules. */
.brand small { letter-spacing: .08em; }
.hero-intro { max-width: 36em; }
.eyebrow, .resource-kind { font-variant-numeric: tabular-nums; }
.section-heading .eyebrow::before { content: ""; display: inline-block; width: 20px; height: 1px; margin-right: 10px; background: var(--accent); vertical-align: middle; }
.section-heading h2 { font-weight: 550; }
.learning-steps li { transition: border-color 180ms; }
.learning-steps li:hover { border-top-color: var(--accent); }
.text-link { border-bottom: 1px solid var(--line); padding-bottom: 4px; }
.text-link:hover { border-color: var(--accent); }
.resource-card:hover, .resource-row:hover { border-top-color: var(--accent); }
.figure-zoom { padding: 16px; }
.figure-zoom-label { border-left: 1px solid var(--line); }