:root{
  --bg:#000; --fg:#ededed; --muted:#9a9aa2; --faint:#5a5a62; --line:#26262b;
  --warm:#ffbf57; --cool:#5fb4ff;
  --serif:"Spectral", Georgia, "Times New Roman", serif;
  --mono:"IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --card:rgba(6,6,9,.66);
  color-scheme:dark;
}
*{box-sizing:border-box}
html{scroll-behavior:auto;background:var(--bg)}
body{margin:0;background:var(--bg);color:var(--fg);font:300 18px/1.6 var(--serif);-webkit-font-smoothing:antialiased;overflow-x:hidden}
a{color:inherit}
#gl{position:fixed;inset:0;width:100vw;height:100vh;height:100lvh;display:block;z-index:0;opacity:0;transition:opacity 1.2s ease}
body.ready #gl{opacity:1}
body.no-gl #gl{display:none}

/* ---------- top bar: the same bar as the landing page (brand, search, nav) */
.bar{position:fixed;top:0;left:0;right:0;z-index:20;padding-top:env(safe-area-inset-top,0px);background:rgba(0,0,0,.82);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-bottom:1px solid #1f1f23;font-family:var(--mono)}
.bar .wrap{max-width:1160px;margin:0 auto;height:52px;display:flex;align-items:center;gap:20px;padding-left:max(20px,env(safe-area-inset-left,0px));padding-right:max(20px,env(safe-area-inset-right,0px))}
.brand{display:inline-flex;align-items:center;gap:10px;color:var(--fg);text-decoration:none;font-size:13px;font-weight:500;letter-spacing:.04em}
/* live cube mark (animated by ../assets/home.js), same as the atlases */
.mark-wrap{position:relative;width:30px;height:30px;flex:none;display:grid;place-items:center}
.mark{width:20px;height:20px;fill:none;stroke:#e8eef5;stroke-width:1.1;stroke-linejoin:round}
#mark{position:absolute;inset:0;width:30px;height:30px;display:block}
.brand.live .mark{display:none}
.home-link{position:relative}
.home-link .mark-wrap::before{content:"";position:absolute;inset:-5px;border-radius:50%;opacity:0;transform:scale(.6);
  background:conic-gradient(from 0deg,#ffbf57,#ff6b9d,#b07cff,#5fb4ff,#3fe0c5,#ffbf57);filter:blur(9px);
  transition:opacity .35s,transform .35s;animation:homeSpin 3s linear infinite;pointer-events:none}
.home-link:hover .mark-wrap::before,.home-link:focus-visible .mark-wrap::before{opacity:.55;transform:scale(1)}
.home-link .mark-wrap{transition:transform .35s cubic-bezier(.3,1.6,.5,1)}
.home-link:hover .mark-wrap,.home-link:focus-visible .mark-wrap{transform:scale(1.15)}
.home-tip{position:absolute;left:50%;top:calc(100% + 6px);transform:translate(-14px,-4px);opacity:0;pointer-events:none;
  font:500 11px/1 var(--mono);letter-spacing:.06em;white-space:nowrap;color:#fff;
  padding:7px 10px;border-radius:999px;background:#0a1422;border:1px solid transparent;
  background-image:linear-gradient(#0a1422,#0a1422),linear-gradient(90deg,#ffbf57,#ff6b9d,#b07cff,#5fb4ff);
  background-origin:border-box;background-clip:padding-box,border-box;box-shadow:0 8px 24px rgba(0,0,0,.45);
  transition:opacity .25s,transform .25s}
.home-tip i{font-style:normal;display:inline-block;transition:transform .25s}
.home-link:hover .home-tip,.home-link:focus-visible .home-tip{opacity:1;transform:translate(-14px,0)}
.home-link:hover .home-tip i{transform:translateX(-3px)}
@keyframes homeSpin{to{rotate:360deg}}
.home-link:hover .mark,.home-link:focus-visible .mark{animation:homeHue 1.6s linear infinite}
@keyframes homeHue{0%{stroke:#ffbf57}25%{stroke:#ff6b9d}50%{stroke:#b07cff}75%{stroke:#5fb4ff}100%{stroke:#ffbf57}}
@media (hover:none){.home-tip{display:none!important}}
@media (prefers-reduced-motion:reduce){.home-link .mark-wrap::before{animation:none}}
.bar .search{margin-left:auto;width:clamp(150px,22vw,250px)}
.bar .nav{display:flex;gap:2px;overflow-x:auto;scrollbar-width:none}
.bar .nav::-webkit-scrollbar{display:none}
.bar .nav a{font:400 12px/1 var(--mono);letter-spacing:.08em;text-transform:uppercase;color:#8a8a91;text-decoration:none;
  padding:9px 9px;position:relative;white-space:nowrap;transition:color .2s}
.bar .nav a:hover,.bar .nav a:focus-visible{color:#ededed}
.bar .nav a::after{content:"";position:absolute;left:9px;right:9px;bottom:2px;height:1px;
  background:linear-gradient(90deg,#ffbf57,#5fb4ff);opacity:.45;transition:opacity .2s}
.bar .nav a:hover::after,.bar .nav a:focus-visible::after{opacity:1}
.stage{display:none}
@media (max-width:480px){.bar .nav a[href="#intro"]{display:none}}
a:focus-visible{outline:1px solid var(--fg);outline-offset:4px}

/* ---------- level title: top right, under the bar */
.hud{position:fixed;right:max(20px,env(safe-area-inset-right,0px));top:calc(64px + env(safe-area-inset-top,0px));z-index:20;display:flex;flex-direction:column;gap:6px;
  padding:10px 14px 11px;border-radius:8px;background:rgba(0,0,0,.55);-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);border:1px solid #ffffff12;
  font:400 12px/1.2 var(--mono);color:var(--muted);letter-spacing:.04em;pointer-events:none;max-width:min(340px,calc(100vw - 120px))}
.hud-title{font:400 10px/1 var(--mono);letter-spacing:.16em;text-transform:uppercase;color:var(--faint)}
.hud-level{white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:var(--fg)}
.hud-level b{color:var(--warm);font-weight:500;margin-right:4px}
.hud-bar{display:block;height:2px;background:#ffffff14;border-radius:2px;overflow:hidden}
.hud-bar i{display:block;height:100%;width:0;background:var(--warm);transition:width .15s linear}
body.past-levels .hud,body.past-levels #scalebar,body.past-levels #index{opacity:0;pointer-events:none;transition:opacity .3s}

/* ---------- level index (right edge) */
#index{position:fixed;right:max(14px,env(safe-area-inset-right));top:50%;transform:translateY(-50%);z-index:20;display:flex;flex-direction:column;gap:2px}
#index a{display:grid;grid-template-columns:auto 22px;align-items:center;justify-content:end;gap:10px;text-decoration:none;padding:5px 0;font:400 11px/1 var(--mono);color:var(--faint)}
#index .t{opacity:0;transform:translateX(6px);transition:.25s;white-space:nowrap;color:var(--muted)}
#index .n{grid-column:2;text-align:right;letter-spacing:.06em}
#index .t{grid-column:1;grid-row:1}
#index i{display:none}
#index a.past .n{color:#8a8a91}
#index a.on .n{color:var(--warm)}
#index:hover .t{opacity:1;transform:none} /* the level panel already names the current level */
#index a:hover .n{color:var(--fg)}
#index a.on{position:relative}
#index a.on::after{content:"";position:absolute;right:-8px;top:4px;bottom:4px;width:2px;background:linear-gradient(var(--warm) calc(var(--p,0)*100%), #333 0)}

/* ---------- scale bar */
#scalebar{position:fixed;right:max(54px,calc(env(safe-area-inset-right) + 40px));bottom:max(22px,env(safe-area-inset-bottom));z-index:20;display:flex;flex-direction:column;align-items:flex-end;gap:6px;font:400 11px/1 var(--mono);color:var(--muted);letter-spacing:.04em;transition:opacity .4s}
#scalebar i{display:block;height:6px;border:1px solid #cfcfd4;border-top:0;min-width:0;transition:width .15s linear}
#scalebar.off{opacity:0}
body.intro #scalebar{opacity:.0}

/* ---------- in-scene labels */
#labels{position:fixed;inset:0;z-index:5;pointer-events:none;overflow:hidden}
.lbl{position:absolute;left:0;top:0;will-change:transform,opacity;transition:opacity .25s;visibility:hidden}
.lbl i{position:absolute;left:-3px;top:-3px;width:6px;height:6px;border-radius:50%;background:var(--fg);box-shadow:0 0 0 3px #0008}
.lbl span{position:absolute;top:-9px;white-space:nowrap;padding-left:14px;font:400 12px/1.25 var(--mono);color:var(--fg);text-shadow:0 1px 6px #000,0 0 2px #000}
.lbl span::before{content:"";position:absolute;left:4px;top:9px;width:8px;height:1px;background:#ededed99}
.lbl b{font-weight:500;display:block}
.lbl small{display:block;color:#c8c8cc;font-size:11px;margin-top:2px}
.lbl.l span{right:0;padding:0 14px 0 0;text-align:right}
.lbl.l span::before{left:auto;right:4px}

/* ---------- narrative */
main{position:relative;z-index:10}
section.lvl{position:relative;height:var(--len,400vh);pointer-events:none}
.beat{position:absolute;left:max(28px,calc(env(safe-area-inset-left) + 28px));width:min(430px,calc(100vw - 56px));padding:22px 24px 20px;border-radius:10px;
  background:var(--card);border:1px solid #ffffff10;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);pointer-events:auto}
.beat h1{font:300 40px/1.12 var(--serif);margin:.15em 0 .45em;letter-spacing:-.01em}
.beat h2{font:400 26px/1.2 var(--serif);margin:0 0 .45em}
.beat p{margin:0 0 .7em}
.beat p:last-child{margin-bottom:0}
.beat.hero{width:min(560px,calc(100vw - 56px));top:3%}
.eyebrow{font:400 11px/1.4 var(--mono)!important;letter-spacing:.14em;text-transform:uppercase;color:var(--warm);margin:0 0 .6em!important}
.hint{font:400 11px/1.4 var(--mono)!important;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin-top:1.2em!important}
.hint::after{content:" ↓";animation:nudge 1.8s ease-in-out infinite;display:inline-block}
@keyframes nudge{50%{transform:translateY(3px)}}
.types{margin:.2em 0 .8em;padding:0;list-style:none}
.types li{margin:0 0 .55em;padding-left:14px;position:relative}
.types li::before{content:"";position:absolute;left:0;top:.72em;width:5px;height:1px;background:var(--warm)}
.types b{font-weight:400;color:var(--fg);font-style:italic}
.cite{font:400 11px/1.6 var(--mono)!important;color:var(--muted);letter-spacing:.03em}
.cite a{color:var(--cool);text-decoration:none;padding:0 1px}
.cite a:hover{text-decoration:underline}
.note{font:400 11.5px/1.5 var(--mono)!important;color:#b0a088;border-left:2px solid #ffbf5755;padding-left:10px}

/* ---------- section lengths and card positions (kept out of the HTML so the page needs no inline styles) */
#intro{--len:260vh}
#intro>.beat:nth-child(1){top:3%}
#intro>.beat:nth-child(2){top:52%}
#landscape{--len:380vh}
#types{--len:440vh}
#cell{--len:400vh}
#nucleus{--len:440vh}
#chromosomes{--len:420vh}
#structure{--len:460vh}
#helix{--len:420vh}
#nucleosomes{--len:400vh}
#chromatin{--len:520vh}
#sequence{--len:480vh}
#regulation{--len:460vh}
#landscape>.beat:nth-child(1){top:3%}
#landscape>.beat:nth-child(2){top:42%}
#landscape>.beat:nth-child(3){top:72%}
#types>.beat:nth-child(1){top:4%}
#types>.beat:nth-child(2){top:34%}
#types>.beat:nth-child(3){top:74%}
#cell>.beat:nth-child(1){top:4%}
#cell>.beat:nth-child(2){top:36%}
#cell>.beat:nth-child(3){top:72%}
#nucleus>.beat:nth-child(1){top:4%}
#nucleus>.beat:nth-child(2){top:30%}
#nucleus>.beat:nth-child(3){top:62%}
#chromosomes>.beat:nth-child(1){top:4%}
#chromosomes>.beat:nth-child(2){top:36%}
#chromosomes>.beat:nth-child(3){top:66%}
#structure>.beat:nth-child(1){top:3%}
#structure>.beat:nth-child(2){top:26%}
#structure>.beat:nth-child(3){top:50%}
#structure>.beat:nth-child(4){top:74%}
#helix>.beat:nth-child(1){top:4%}
#helix>.beat:nth-child(2){top:34%}
#helix>.beat:nth-child(3){top:64%}
#nucleosomes>.beat:nth-child(1){top:4%}
#nucleosomes>.beat:nth-child(2){top:36%}
#nucleosomes>.beat:nth-child(3){top:66%}
#chromatin>.beat:nth-child(1){top:3%}
#chromatin>.beat:nth-child(2){top:30%}
#chromatin>.beat:nth-child(3){top:58%}
#sequence>.beat:nth-child(1){top:3%}
#sequence>.beat:nth-child(2){top:30%}
#sequence>.beat:nth-child(3){top:60%}
#regulation>.beat:nth-child(1){top:3%}
#regulation>.beat:nth-child(2){top:36%}
#regulation>.beat:nth-child(3){top:68%}

/* ---------- references */
.refs{position:relative;z-index:10;background:linear-gradient(#0000,#000 160px);padding:200px 0 80px}
.refs .wrap{max-width:920px;margin:0 auto;padding:0 max(24px,env(safe-area-inset-left))}
.refs h2{font:300 40px/1.15 var(--serif);margin:0 0 .4em}
.refs .lead{color:var(--muted);max-width:62ch}
.refgroup h3{font:400 11px/1.4 var(--mono);letter-spacing:.14em;text-transform:uppercase;color:var(--warm);margin:2.4em 0 .8em;padding-top:1em;border-top:1px solid var(--line)}
.refgroup ol{margin:0;padding-left:2.4em}
.refgroup li{margin:0 0 .75em;font-size:16px;line-height:1.5;scroll-margin-top:80px}
.refgroup li::marker{font:400 12px var(--mono);color:var(--faint)}
.refgroup li:target{background:#ffbf5714;outline:1px solid #ffbf5744;border-radius:4px}
.refgroup .ra{color:var(--muted)}
.refgroup em{color:var(--muted)}
.refgroup a{font:400 12px var(--mono);color:var(--cool);text-decoration:none;word-break:break-all}
.refgroup a:hover{text-decoration:underline}
.about{margin-top:3em;padding-top:1.4em;border-top:1px solid var(--line);color:var(--muted)}
.about h3{font:400 20px var(--serif);color:var(--fg);margin:0 0 .5em}
.small{font:400 12px/1.6 var(--mono);color:var(--faint)}

#glFallback{position:fixed;left:50%;top:40%;transform:translate(-50%,-50%);z-index:4;max-width:420px;padding:18px 22px;border:1px solid var(--line);border-radius:10px;font:400 13px/1.6 var(--mono);color:var(--muted)}

#lvlErr{position:fixed;left:50%;bottom:max(20px,env(safe-area-inset-bottom));transform:translateX(-50%);z-index:30;max-width:min(520px,90vw);font:400 12px/1.5 var(--mono);color:#ffcf9a;background:#1a0f08e6;border:1px solid #ffbf5744;border-radius:8px;padding:8px 12px}
#lvlErr p{margin:0}

/* ---------- footer (matches the landing page) */
.site-footer{position:relative;z-index:10;background:#000;border-top:1px solid var(--line)}
.footer-grid{max-width:920px;margin:0 auto;padding-block:32px 28px;padding-left:max(24px,env(safe-area-inset-left,0px));padding-right:max(24px,env(safe-area-inset-right,0px));
  display:grid;grid-template-columns:1fr auto;gap:22px 32px;font-family:var(--mono)}
.footer-brand{display:flex;flex-direction:column;gap:6px}
.footer-brand b{font-size:14px;font-weight:500;letter-spacing:.04em;color:var(--fg)}
.footer-brand span{font-size:12px;color:var(--muted)}
.footer-nav{display:flex;gap:22px;align-items:flex-start}
.footer-nav a{color:var(--muted);text-decoration:none;font-size:12px;letter-spacing:.08em;text-transform:uppercase}
.footer-nav a:hover,.footer-nav a:focus-visible{color:var(--fg)}
.footer-copy{grid-column:1/-1;margin:0;padding-top:18px;border-top:1px solid var(--line);font-size:11px;letter-spacing:.06em;color:var(--faint)}
.refs{padding-bottom:48px}

/* ---------- tablet & phone */
@media (max-width:900px){
  #index .t{display:none}
}
@media (max-width:760px){
  body{font-size:16.5px}
  .bar .wrap{gap:10px}
  .bar .search{flex:1 1 auto;width:auto;margin-left:4px}
  .bar .nav a{padding:9px 6px;letter-spacing:.05em;font-size:11px}
  .bar .nav a::after{left:6px;right:6px}
  .bar .search{min-width:0}
  .bar .nav{flex:none}
  .hud{right:10px;top:calc(58px + env(safe-area-inset-top,0px));padding:7px 10px 8px;max-width:calc(100vw - 90px)}
  .hud-title{display:none}
  #intro>.beat:nth-child(1){top:calc(3% + 44px)} /* clear the level panel on the first screen */
  #index{right:6px;gap:0}
  #index a{padding:3px 0;font-size:9.5px}
  #index a .n{width:18px}
  #scalebar{right:34px;bottom:max(14px,env(safe-area-inset-bottom))}
  /* cards dock to the lower part of the screen so the scene above stays visible */
  .beat,.beat.hero{left:12px;width:calc(100vw - 50px);padding:16px 16px 14px;background:rgba(6,6,9,.78)}
  .beat h1{font-size:30px}
  .beat h2{font-size:22px}
  .lbl span{font-size:10.5px}
  .lbl small{display:none}
  .refs h2{font-size:30px}
  .refgroup li{font-size:15px}
  .refgroup ol{padding-left:2em}
  .footer-grid{grid-template-columns:1fr}
}
@media (prefers-reduced-motion:reduce){
  .hint::after{animation:none}
  #gl{transition:none}
}