/* Foundation: global type, links, and keyboard navigation. */
html { scroll-behavior: smooth; scroll-padding-top: var(--nav-height); }
@view-transition { navigation: auto; }
::view-transition-old(root), ::view-transition-new(root) { animation-duration: 260ms; animation-timing-function: var(--ease); }
body { background: var(--canvas); color: var(--text); font: var(--text-base)/var(--leading-body) var(--font); }
a { color: inherit; text-decoration: none; }
a:hover { color: var(--hero-accent); }
:focus-visible { outline: var(--focus-width) solid var(--accent-bright); outline-offset: var(--focus-offset); }
button { color: inherit; }
h1, h2, h3 { font-weight: var(--weight-light); line-height: var(--leading-heading); letter-spacing: var(--tracking-tight); text-wrap: balance; }
h1 { font-size: var(--text-title); }
h2 { font-size: var(--text-h2); }
h3 { font-size: var(--text-h3); }
p { max-width: var(--copy-width); }
p + p { margin-top: var(--space-5); }
.container { width: min(calc(100% - var(--gutter) * 2), var(--content-width)); margin-inline: auto; }
.section { padding-block: var(--section-space); }
.rule { border-top: 0; }
.eyebrow { color: var(--muted); font: var(--text-xs)/var(--leading-body) var(--mono); font-weight: var(--weight-bold); letter-spacing: var(--tracking-label); text-transform: uppercase; margin-bottom: var(--space-5); }
.lead { color: var(--muted); font-size: var(--text-lead); margin-top: var(--space-6); }
.muted { color: var(--muted); }
.skip-link { position: fixed; top: var(--space-4); left: var(--space-4); z-index: 100; padding: var(--space-3) var(--space-5); background: var(--canvas); transform: translateY(-200%); }
.skip-link:focus { transform: translateY(0); }
/* Shared header: all page links are edited in partials/header.html. */
.site-header { position: fixed; inset: var(--zero) var(--zero) auto; z-index: 20; isolation: isolate; min-height: var(--nav-height); background: var(--nav-bg); transition: background var(--duration-fast), opacity 340ms var(--ease); }
.site-header.is-away { opacity: 0; pointer-events: none; }
.home .site-header:not(.menu-open) { background: transparent; color: var(--text); border-color: transparent; }
.site-header.is-scrolled { background: var(--nav-bg); backdrop-filter: blur(var(--space-3)); }
.home .site-header.is-scrolled:not(.menu-open) { background: transparent; backdrop-filter: none; box-shadow: none; }
.nav-shell { min-height: var(--nav-height); display: flex; align-items: center; justify-content: space-between; gap: clamp(2rem, 5vw, 5rem); }
.brand { flex: 0 0 auto; font-size: 1.05rem; font-weight: 700; color: inherit; text-decoration: none; letter-spacing: 0.12em; line-height: 1; }
.brand span { color: var(--hero-accent); }
.nav-links { display: grid; gap: var(--space-2); list-style: none; margin: var(--zero); padding: var(--space-4) var(--gutter) var(--space-6); position: absolute; top: 100%; left: var(--zero); width: 100%; max-height: 0; overflow: hidden; visibility: hidden; opacity: 0; transform: translateY(-0.5rem); pointer-events: none; background: var(--canvas); color: var(--text); border-bottom: var(--rule) solid var(--line); transition: max-height 320ms var(--ease), opacity var(--duration-fast), transform var(--duration-fast), visibility var(--duration-fast); }
.nav-links.is-open { max-height: 28rem; visibility: visible; opacity: 1; transform: translateY(0); pointer-events: auto; }
.nav-links a { position: relative; display: block; padding-block: var(--space-2); color: inherit; text-decoration: none; font-size: 0.76rem; font-weight: 700; letter-spacing: 0.075em; text-transform: uppercase; transition: color var(--duration-fast); }
.nav-links a::after { content: ""; position: absolute; left: 0; right: 0; bottom: 0.2rem; height: 1px; background: currentColor; transform: scaleX(0); transform-origin: right center; transition: transform 340ms var(--ease); }
.nav-links a:hover::after, .nav-links a:focus-visible::after { transform: scaleX(1); transform-origin: left center; }
.nav-links a[aria-current] { color: var(--text); }
.nav-links a[aria-current]::after { transform: scaleX(1); opacity: 0.48; }
.menu-toggle { width: var(--control-size); height: var(--control-size); display: grid; place-content: center; gap: 5px; background: var(--transparent); border: 0; padding: var(--space-2); }
.menu-toggle span { display: block; width: 1.45rem; height: 1px; background: currentColor; transform-origin: center; transition: transform 320ms var(--ease), opacity 220ms ease; }
.menu-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.menu-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.menu-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }
.site-header .brand, .site-header .menu-toggle, .site-header .nav-links li { animation: nav-enter 620ms var(--ease) both; }
.site-header .nav-links li:nth-child(2) { animation-delay: 45ms; }
.site-header .nav-links li:nth-child(3) { animation-delay: 90ms; }
.site-header .nav-links li:nth-child(4) { animation-delay: 135ms; }
.site-header .nav-links li:nth-child(5) { animation-delay: 180ms; }
.site-header .nav-links li:nth-child(6) { animation-delay: 225ms; }
/* Hero: a media wrapper makes the generated scene replaceable in one line. */
.hero { position: relative; overflow: hidden; min-height: var(--hero-min-height); height: 100svh; max-height: 67.5rem; background: var(--hero-canvas); color: var(--hero-text); display: flex; align-items: center; border-bottom: var(--rule) solid var(--line); }
.hero-media { position: absolute; inset: var(--zero); overflow: hidden; }
.hero-media > video, .hero-media > img:not(.hero-wireframe) { width: 100%; height: 100%; object-fit: cover; }
.hero-shade { position: absolute; inset: 0; background: linear-gradient(90deg, rgba(5, 6, 7, 0.94) 0%, rgba(5, 6, 7, 0.66) 42%, rgba(5, 6, 7, 0.18) 72%), linear-gradient(0deg, rgba(5, 6, 7, 0.78) 0%, transparent 48%); }
.hero-mesh { display: none; }
.hero-wireframe { position: absolute; width: var(--hero-graphic-mobile); max-width: none; right: var(--hero-graphic-offset); top: var(--hero-graphic-top-mobile); opacity: 0.25; filter: grayscale(1) invert(1); }
.hero-boundary { display: none; }
.hero-content { position: relative; z-index: 1; padding-top: var(--nav-height); text-align: left; pointer-events: none; }
.hero-content a { pointer-events: auto; }
.hero h1 { font-size: clamp(3.2rem, 8.5vw, 7.5rem); max-width: 69rem; line-height: 1.05; letter-spacing: -0.065em; }
.hero h1 em { color: var(--hero-accent); font-style: normal; }
.hero .eyebrow, .hero .lead { color: var(--hero-muted); }
.hero .lead { max-width: var(--copy-width); font-size: var(--text-lead); }
.hero-meta { position: absolute; inset: auto var(--zero) var(--space-6); display: flex; justify-content: space-between; flex-wrap: wrap; gap: var(--space-3); font: var(--text-xs)/var(--leading-body) var(--mono); color: var(--hero-muted); }
.actions { display: flex; flex-wrap: wrap; gap: var(--space-5); margin-top: var(--space-7); }
.button { display: inline-flex; align-items: center; justify-content: center; gap: var(--space-5); min-height: var(--control-size); padding: var(--space-3) var(--space-5); border: var(--rule) solid var(--text); border-radius: var(--radius); color: var(--text); background: var(--transparent); text-decoration: none; font-size: var(--text-sm); font-weight: var(--weight-medium); }
.button { transition: color var(--duration-fast), background var(--duration-fast), border-color var(--duration-fast), transform var(--duration-fast); }
.button:hover { color: var(--text); background: var(--surface); border-color: var(--hero-accent); transform: translateY(-2px); }
.button-primary { color: #fff; background: var(--accent); border-color: var(--hero-accent); }
.hero .button { color: var(--hero-text); border-color: var(--hero-line); }
.hero .button-primary { background: var(--hero-accent); color: var(--hero-canvas); }
/* Editorial layout: separate content with space and softly surfaced groups. */
.page-heading { padding-top: calc(var(--nav-height) + var(--space-5)); padding-bottom: var(--space-7); min-height: 0; display: flex; flex-direction: column; justify-content: flex-end; }
.page-heading + .section { padding-top: var(--space-6); }
.gallery-page .page-heading { padding-bottom: var(--space-5); }
.gallery-page .page-heading + .section { padding-top: 0; }
.progress-page .page-heading, .contact-page .page-heading { padding-bottom: var(--space-5); }
.progress-page .page-heading + .section, .contact-page .page-heading + .section { padding-top: 0; }
.page-heading h1 { font-size: clamp(2.75rem, 5vw, 4.5rem); line-height: 1.04; max-width: 64rem; }
.team-heading { padding-bottom: var(--space-6); }
.team-heading + .section { padding-top: var(--space-5); }
.split { display: grid; gap: var(--space-7); }
.info-panel { padding: var(--space-7); background: linear-gradient(145deg, #1b1d20, #141619); border-radius: 1rem; box-shadow: inset 0 0 0 var(--rule) rgba(225, 228, 231, 0.08); }
.info-panel > div:last-child { color: var(--muted); }
.stack > * + * { margin-top: var(--space-6); }
.feature-grid { display: grid; gap: var(--space-5); margin-top: var(--space-8); }
.feature-grid article { min-height: 100%; padding: var(--space-6); background: linear-gradient(145deg, #1b1d20, #141619); border-radius: 1rem; box-shadow: inset 0 0 0 var(--rule) rgba(225, 228, 231, 0.08); }
.feature-grid p { color: var(--muted); margin-top: var(--space-4); }
.feature-grid p a { display: inline-flex; align-items: center; min-height: 2.5rem; padding: var(--space-2) var(--space-4); border-radius: 999px; box-shadow: inset 0 0 0 var(--rule) rgba(225, 228, 231, 0.2); color: var(--text); font-size: var(--text-sm); transition: color var(--duration-fast), background var(--duration-fast), box-shadow var(--duration-fast); }
.feature-grid p a:hover { color: var(--hero-canvas); background: var(--hero-accent); box-shadow: inset 0 0 0 var(--rule) var(--hero-accent); }
.design-overview { display: grid; gap: var(--space-5); margin-top: var(--space-3); }
.design-overview > .info-panel { padding: var(--space-6); }
.design-overview h3 { font-size: var(--text-h3); margin-bottom: var(--space-3); }
.design-overview p { color: var(--muted); }
.subsystem { padding: var(--space-7); background: var(--surface); border-radius: 1rem; box-shadow: inset 0 0 0 var(--rule) rgba(225, 228, 231, 0.08); display: grid; gap: var(--space-6); scroll-margin-top: var(--nav-height); }
.subsystem p { color: var(--muted); }
.subsystem .summary { color: var(--text); font-size: var(--text-lead); margin-bottom: var(--space-5); }
.subsystem-nav { display: flex; flex-wrap: wrap; gap: var(--space-3) var(--space-6); margin-top: var(--space-7); }
/* Team: initial portraits can be replaced by photos in data/team.json. */
.team-grid { display: grid; grid-template-columns: minmax(0, 1fr); gap: var(--space-8) var(--space-6); }
.portrait { position: relative; background: var(--surface); aspect-ratio: 4 / 5; display: grid; place-items: center; margin-bottom: var(--space-5); overflow: hidden; border-radius: 1.25rem; }
.portrait img { width: 100%; height: 100%; object-fit: cover; position: absolute; inset: var(--zero); }
.team-card:not([data-member="xiangxi-mall-wang"]) .portrait img { object-position: center 68%; transform: scale(1.08); }
.team-skeleton > :not(.portrait) { visibility: hidden; }
.team-card .eyebrow { margin: var(--space-3) var(--zero); }
.team-card { display: flex; flex-direction: column; }
.team-card h2 { min-height: 2.4em; }
.team-card .eyebrow { min-height: 3.4em; }
.team-card .profile-link { display: inline-block; align-self: flex-start; padding-block: var(--space-3); margin-top: auto; }
/* Timeline: statuses include words, so color is never the sole signal. */
.timeline { list-style: none; padding: var(--zero); margin: var(--zero); display: grid; gap: var(--space-3); }
.progress-page .timeline-intro { transform: translateY(var(--space-5)); }
.milestone { padding: var(--space-6); background: var(--surface); border-radius: 1rem; box-shadow: inset 0 0 0 var(--rule) rgba(225, 228, 231, 0.08); display: grid; gap: var(--space-5); }
.milestone p { margin-top: var(--space-3); color: var(--muted); }
.status { display: inline-block; font: var(--text-sm)/var(--leading-body) var(--mono); color: var(--muted); margin-top: var(--space-3); }
.status.complete, .status.in-progress { color: var(--hero-accent); }
/* Gallery: filter buttons, technical placeholders, and native modal dialog. */
.filters { display: flex; flex-wrap: wrap; gap: var(--space-2); margin-bottom: var(--space-6); }
.filter { border: var(--rule) solid var(--line); background: var(--transparent); padding: var(--space-2) var(--space-5); border-radius: var(--radius); min-height: var(--control-size); }
.filter { transition: color var(--duration-fast), background var(--duration-fast), border-color var(--duration-fast), transform var(--duration-fast); }
.filter:hover { border-color: var(--hero-accent); transform: translateY(-1px); }
.filter[aria-pressed="true"] { background: var(--accent); color: var(--text); border-color: var(--hero-accent); }
.gallery-count { color: var(--muted); font-size: var(--text-sm); margin-bottom: var(--space-6); }
.gallery-grid { display: grid; gap: var(--space-7) var(--space-6); }
.gallery-open { display: block; border: var(--zero); padding: var(--zero); width: 100%; background: var(--surface); }
.blueprint { display: grid; place-items: center; aspect-ratio: 4 / 3; background: var(--surface); border: var(--rule) solid var(--line); border-radius: 1.25rem; color: var(--muted); font-size: var(--text-sm); letter-spacing: var(--tracking-label); text-transform: uppercase; }
.blueprint img { width: 100%; height: 100%; object-fit: cover; }
.gallery-grid figcaption { margin-top: var(--space-4); color: var(--muted); font-size: var(--text-sm); }
.lightbox { width: min(calc(100% - var(--gutter)), var(--dialog-width)); max-height: 90svh; padding: var(--space-5); background: var(--canvas); color: var(--text); border: var(--rule) solid var(--line); border-radius: var(--radius); }
.lightbox::backdrop { background: var(--overlay); }
.lightbox-bar { display: flex; align-items: center; justify-content: space-between; gap: var(--space-5); margin-bottom: var(--space-4); }
.lightbox h2 { font-size: var(--text-lead); }
.lightbox .blueprint { aspect-ratio: auto; min-height: 35svh; }
.lightbox img { max-height: 65svh; width: 100%; object-fit: contain; }
.lightbox figcaption { margin-top: var(--space-4); }
.lightbox-controls { display: flex; justify-content: space-between; gap: var(--space-4); margin-top: var(--space-5); }
body.modal-open { overflow: hidden; }
/* Shared footer and useful empty/error states. */
.site-footer { margin-top: var(--space-6); padding-block: var(--space-7); background: var(--surface); }
.footer-grid { display: flex; flex-wrap: wrap; justify-content: space-between; gap: var(--space-6); }
.footer-grid p { color: var(--muted); font-size: var(--text-sm); margin-top: var(--space-2); }
.footer-links { display: flex; flex-wrap: wrap; gap: var(--space-5); align-items: flex-start; font-size: var(--text-sm); }
.load-error { padding-block: var(--space-5); color: var(--muted); }
/* Motion stays progressive: content is visible if JavaScript fails. */
.reveal.is-pending { opacity: 0; transform: translateY(var(--reveal-offset)); }
.reveal { transition: opacity var(--duration-reveal) var(--ease), transform var(--duration-reveal) var(--ease); }
@keyframes mesh-drift { to { transform: scale(1.08) translateX(var(--drift-x)); } }
@keyframes wire-drift { to { transform: translate(var(--drift-x), var(--drift-y)) rotate(2deg); } }
@keyframes nav-enter { from { opacity: 0; transform: translateY(-0.85rem); } to { opacity: 1; transform: translateY(0); } }
/* Layout breakpoint: 768px matches the navigation media query in include.js. */
@media (min-width: 768px) {
  .menu-toggle { display: none; }
  .nav-shell nav { margin-left: auto; }
  .nav-links, .nav-links.is-open { display: flex; position: static; width: auto; max-height: none; overflow: visible; visibility: visible; opacity: 1; transform: none; pointer-events: auto; background: var(--transparent); color: inherit; border: var(--zero); padding: var(--zero); gap: clamp(1.2rem, 2.2vw, 2.2rem); }
  .split { grid-template-columns: 0.85fr 1.15fr; gap: var(--space-9); }
  .feature-grid { grid-template-columns: repeat(3, 1fr); }
  .gallery-grid { grid-template-columns: repeat(2, 1fr); }
  .subsystem { grid-template-columns: 1fr 1.4fr; gap: var(--space-8); }
  .milestone { grid-template-columns: 1fr 2fr; }
  .hero-wireframe { width: var(--hero-graphic); right: var(--zero); top: var(--hero-graphic-top); }
  .team-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}
@media (min-width: 480px) and (max-width: 767px) {
  .team-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
/* About page: a tighter, denser reading layout. */
.about-page .page-heading { min-height: 0; padding-bottom: var(--space-7); }
.about-page .section { padding-block: var(--space-6); }
.about-page .page-heading + .section { padding-top: 0; }
.about-page main > .section:last-of-type { padding-bottom: var(--space-9); }
.brief-grid { display: grid; gap: var(--space-5); }
.brief-grid .info-panel { display: flex; flex-direction: column; gap: var(--space-4); }
.brief-grid .info-panel .eyebrow { margin-bottom: var(--zero); }
.brief-grid .info-panel h2 { font-size: clamp(1.75rem, 3vw, 2.5rem); }
.brief-grid .info-panel p:last-child { color: var(--muted); }
.about-page .feature-grid { margin-top: var(--space-6); }
.about-page .precedents article { display: grid; grid-template-rows: auto 1fr auto; }
.about-page .precedents h3 { font-size: clamp(1rem, 1.8vw, 1.5rem); white-space: nowrap; }
.home main > .section { padding-block: clamp(2.5rem, 4vw, 3.5rem); }
.home-mission .mission-layout { display: grid; gap: var(--space-5); align-items: stretch; }
.home-mission .mission-copy { display: grid; grid-template-rows: 1fr auto; padding: var(--space-4) var(--space-5); border-radius: 1rem; background: var(--surface); box-shadow: inset 0 0 0 var(--rule) var(--line); }
.home-mission .lead { align-self: center; margin-top: 0; color: var(--text); font-size: var(--text-lead); line-height: 1.4; }
.home-mission .mission-copy a { display: block; padding-top: var(--space-2); border-top: var(--rule) solid var(--line); color: var(--hero-accent); font-size: var(--text-sm); }
.home .feature-grid { margin-top: var(--space-6); }
.contact-channels { padding-top: var(--space-5); padding-bottom: var(--space-9); }
.contact-row { display: grid; gap: var(--space-6); padding-block: var(--space-7); border-top: var(--rule) solid var(--line); }
.contact-row:last-child { border-bottom: var(--rule) solid var(--line); }
.contact-row .eyebrow { margin-bottom: var(--space-4); }
.contact-row h2 { font-size: clamp(2rem, 4vw, 3.25rem); }
.contact-row-content { display: flex; flex-direction: column; align-items: flex-start; gap: var(--space-5); }
.contact-row-content p { max-width: 38rem; }
@media (min-width: 768px) {
  .home-mission .mission-layout { grid-template-columns: 0.85fr 1.15fr; gap: var(--space-9); }
  .contact-row { grid-template-columns: 0.85fr 1.15fr; gap: var(--space-9); }
}
@media (min-width: 768px) {
  .brief-grid { grid-template-columns: 1fr 1fr; }
  .design-overview { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
/* Respect motion preferences for all transitions and decorative animation. */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .reveal.is-pending { opacity: 1; transform: none; }
}

/* Data section headings stay subordinate to page titles. */
.team-card h2, .milestone h2, .subsystem h2 { font-size: var(--text-h3); }

/* Decorative movement is pausable, in addition to respecting reduced motion. */
.hero.motion-ready .hero-mesh { animation: mesh-drift var(--duration-drift) var(--ease) infinite alternate; }
.hero.motion-ready .hero-wireframe { animation: wire-drift var(--duration-drift) var(--ease) infinite alternate; }
.hero.motion-paused .hero-mesh, .hero.motion-paused .hero-wireframe { animation-play-state: paused; }
.motion-toggle { color: var(--hero-muted); background: var(--transparent); border: var(--zero); padding: var(--zero); min-height: var(--control-size); font-size: var(--text-sm); text-decoration: none; }
.hero-meta { align-items: center; }

/* Keep links and keyboard focus legible over the dark hero in either palette. */
.home .site-header:not(.is-scrolled):not(.menu-open) .brand span,
.home .site-header:not(.is-scrolled):not(.menu-open) .nav-links a[aria-current] { color: var(--hero-accent); }
.hero :focus-visible,
.home .site-header:not(.is-scrolled):not(.menu-open) :focus-visible { outline-color: var(--hero-accent); }