/* ============================================================
   base.css  —  shared across every topic page.
   Edit tokens here to re-skin the whole site at once.
   ============================================================ */
@import url('https://fonts.googleapis.com/css2?family=Young+Serif&family=Hanken+Grotesk:wght@400;500;600;700;800&display=swap');
/* Fraunces, Nunito and Caveat are no longer used. */

:root{
  --paper:#FBF7EF;          /* warm content canvas */
  --paper-card:#FFFFFF;
  --ink:#1C2E39;            /* deep fjord slate */
  --ink-soft:#52606C;
  --line:#EEE6D5;           /* warm card border */

  /* the dark “mead-hall” surface — sidebar + hero bands */
  --hall-1:#26404E;
  --hall-2:#1C2E39;
  --gold:#E2A93E;           /* primary accent / CTAs / active state */
  --gold-deep:#A07A2E;      /* gold on light backgrounds (section eyebrows) */

  /* cold -> hot ramp for interactives (recoloured live by the slider) */
  --cold:#4C86B8;
  --cool:#2FA39A;
  --warm:#E2A93E;
  --hot:#D2603F;
  --accent:var(--cold);

  /* subject identities — pulled from the mascot palette */
  --sub-chemistry:#6FA04A;
  --sub-physics:#4C86B8;
  --sub-biology:#D2603F;
  --sub-maths:#2FA39A;

  --shadow:0 18px 40px -34px rgba(31,46,57,.6);
  --radius:22px;
  --sidebar-w:304px;

  --font-display:"Young Serif",Georgia,serif;
  --font-body:"Hanken Grotesk",system-ui,sans-serif;
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  display:flex;
  min-height:100vh;
  background:
    radial-gradient(1200px 600px at 90% -10%, rgba(47,127,209,.06), transparent 60%),
    radial-gradient(1000px 600px at -10% 110%, rgba(232,85,59,.05), transparent 60%),
    var(--paper);
  color:var(--ink);
  font-family:var(--font-body);
  font-size:18px;line-height:1.65;-webkit-font-smoothing:antialiased;
}

/* ============================================================
   SIDEBAR
   ============================================================ */
.sidebar{
  flex:0 0 var(--sidebar-w);
  position:sticky;top:0;align-self:flex-start;
  height:100vh;overflow-y:auto;
  background:#fff;border-right:1px solid var(--line);
  padding:22px 16px 40px;
}
.sidebar__brand{padding:6px 10px 18px;border-bottom:1px solid var(--line);margin-bottom:12px}
.sidebar__title{display:block;font-family:var(--font-display);font-weight:700;font-size:1.3rem;line-height:1.1}
.sidebar__sub{display:block;font-family:var(--font-display);font-size:1.15rem;color:var(--ink-soft)}

.navgroup{margin-bottom:2px}
.navgroup[data-subject="chemistry"]{--sub:var(--sub-chemistry)}
.navgroup[data-subject="physics"]{--sub:var(--sub-physics)}
.navgroup[data-subject="biology"]{--sub:var(--sub-biology)}
.navgroup[data-subject="maths"]{--sub:var(--sub-maths)}

/* generic collapsible column (used at every level) */
.col__hd{
  display:flex;align-items:center;gap:8px;width:100%;
  background:none;border:none;cursor:pointer;text-align:left;color:var(--ink);
  border-radius:9px;font-family:var(--font-body);
}
.col__hd:hover{background:#f6f3ec}
.col__hd:focus-visible{outline:3px solid var(--sub);outline-offset:1px}
.col__name{flex:1;line-height:1.25}
.col__chev{color:var(--ink-soft);transition:transform .2s ease;font-size:.8rem}
.col[data-collapsed] > .col__hd .col__chev{transform:rotate(-90deg)}
.col[data-collapsed] > .col__bd{display:none}

/* level: subject */
.col[data-level="subject"] > .col__hd{padding:10px;font-weight:800;font-size:16px}
.navsubject__dot{width:11px;height:11px;border-radius:50%;background:var(--sub);flex:0 0 auto}
.col[data-level="subject"] > .col__bd{padding-left:6px}

/* level: stage */
.col[data-level="stage"] > .col__hd{padding:7px 10px;font-weight:800;font-size:11px;color:var(--ink-soft);text-transform:uppercase;letter-spacing:.05em}
.col[data-level="stage"]{border-left:2px solid var(--line);margin-left:10px}
.col[data-level="stage"] > .col__bd{padding-left:4px}

/* level: chapter */
.col[data-level="chapter"] > .col__hd,.col--marker .col__hd--static{
  display:flex;gap:8px;align-items:baseline;padding:6px 10px;font-size:13.5px;font-weight:700;color:var(--ink);width:100%;border-radius:9px;
}
.col__no{
  flex:0 0 auto;min-width:20px;height:19px;padding:0 5px;border-radius:6px;
  background:color-mix(in srgb,var(--sub) 16%,#fff);color:var(--sub);
  font-weight:800;font-size:11px;display:inline-grid;place-items:center;
}
.col--marker{margin-left:10px}
.col--marker .col__hd--static{color:#9a93861f;cursor:default}
.col--marker .col__name{color:#aaa298;font-weight:600}
.col[data-level="chapter"]{margin-left:10px}

/* topics */
.navtopics{list-style:none;margin:2px 0 8px;padding:0 0 0 8px}
.navlink{
  display:block;text-decoration:none;color:var(--ink-soft);
  padding:7px 12px 7px 24px;border-radius:9px;position:relative;
  font-size:13px;font-weight:600;line-height:1.3;
}
.navlink::before{content:"";position:absolute;left:12px;top:14px;width:6px;height:6px;border-radius:50%;background:var(--line)}
.navlink:hover{background:#f6f3ec;color:var(--ink)}
.navlink.is-active{background:color-mix(in srgb,var(--sub) 14%,#fff);color:var(--ink);font-weight:800}
.navlink.is-active::before{background:var(--sub)}
.navlink__label{font-family:var(--font-display);font-size:12.5px;color:inherit;margin-right:6px}
.navlink--soon{color:#b7b0a4;cursor:default}
.navlink--soon::before{background:#e4ded3}
.navlink--soon em{font-style:normal;font-size:9.5px;font-weight:800;text-transform:uppercase;letter-spacing:.05em;color:#c3bcae;border:1px solid #e4ded3;border-radius:20px;padding:1px 6px;margin-left:4px}

/* mobile toggle */
.navtoggle{display:none}
.navbackdrop{display:none}

/* ============================================================
   MAIN CONTENT
   ============================================================ */
.content{flex:1 1 auto;min-width:0}
.wrap{max-width:880px;margin:0 auto;padding:0 26px}

.hero{padding:60px 26px 26px}
.eyebrow{font-family:var(--font-display);font-size:1.5rem;color:var(--accent);transition:color .4s ease}
h1{
  font-family:var(--font-display);font-weight:600;
  font-size:clamp(2.3rem,6vw,3.9rem);line-height:1.03;
  margin:.08em 0 .25em;letter-spacing:-.01em;
}
.hero .lead{font-size:1.2rem;color:var(--ink-soft);max-width:640px}
.dots{display:flex;gap:10px;margin:24px 0 0}
.dots span{width:14px;height:14px;border-radius:50%;display:block}
.dots .s{background:var(--cold)} .dots .l{background:var(--cool)} .dots .g{background:var(--hot)}

section{padding:26px 0}
.tag{font-family:var(--font-display);font-size:1.45rem;color:var(--ink-soft);display:inline-block;margin-bottom:2px}
h2{font-family:var(--font-display);font-weight:600;font-size:clamp(1.55rem,3.6vw,2.25rem);margin:.1em 0 .5em;letter-spacing:-.01em}
h3{font-family:var(--font-body);font-weight:800;font-size:1.15rem;margin:1.2em 0 .3em;color:var(--ink)}
p{margin:0 0 1em}

.card{background:var(--paper-card);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);padding:26px}
.prose p{font-size:1.12rem;color:#2c3650}
.prose strong{color:var(--ink)}
mark{background:linear-gradient(transparent 55%,#ffe39a 55%);padding:0 .1em;color:inherit}

/* data tables */
.dtable{width:100%;border-collapse:collapse;margin:.4em 0 .2em;font-size:.99rem}
.dtable caption{caption-side:top;text-align:left;font-family:var(--font-display);font-size:1.2rem;color:var(--ink-soft);margin-bottom:6px}
.dtable th,.dtable td{border:1px solid var(--line);padding:10px 12px;text-align:left;vertical-align:top}
.dtable thead th{background:#f3efe7;font-weight:800;color:var(--ink)}
.dtable tbody th{font-weight:800;text-transform:capitalize}
.dtable tbody tr[data-state] th::before{content:"";display:inline-block;width:9px;height:9px;border-radius:50%;margin-right:8px;vertical-align:middle}
.dtable tr[data-state="solid"] th::before{background:var(--cold)}
.dtable tr[data-state="liquid"] th::before{background:var(--cool)}
.dtable tr[data-state="gas"] th::before{background:var(--hot)}
.dtable tr[data-state].is-active{background:color-mix(in srgb,var(--accent) 13%,#fff)}
.dtable tr[data-state].is-active th,.dtable tr[data-state].is-active td{border-color:color-mix(in srgb,var(--accent) 35%,var(--line))}

/* interactive sim panel */
.sim-grid{display:grid;grid-template-columns:1.15fr .85fr;gap:22px;align-items:stretch}
@media(max-width:720px){.sim-grid{grid-template-columns:1fr}}
.sim-left{position:relative;display:flex}
canvas.box{width:100%;height:100%;min-height:320px;display:block;background:#0f1626;border-radius:14px;touch-action:none}
.figure-svg{width:100%;height:auto;display:block;background:#0f1626;border-radius:14px}
.state-flash{position:absolute;top:14px;left:50%;transform:translateX(-50%);font-family:var(--font-display);font-size:1.8rem;color:#fff;background:rgba(0,0,0,.28);padding:2px 16px;border-radius:30px;opacity:0;transition:opacity .25s ease;pointer-events:none;white-space:nowrap}
.controls{display:flex;flex-direction:column;gap:18px;justify-content:center}
.seg-btns{display:flex;gap:10px}
.seg-btns button{flex:1;font-family:var(--font-body);font-weight:800;font-size:1rem;padding:12px 6px;border-radius:13px;border:2px solid var(--line);background:#fff;color:var(--ink-soft);cursor:pointer;transition:.18s}
.seg-btns button .ico{display:block;font-size:1.5rem;margin-bottom:2px}
.seg-btns button[data-on="true"]{color:#fff;border-color:transparent}
.seg-btns button.solid[data-on="true"]{background:var(--cold)}
.seg-btns button.liquid[data-on="true"]{background:var(--cool)}
.seg-btns button.gas[data-on="true"]{background:var(--hot)}
.seg-btns button:focus-visible{outline:3px solid var(--ink);outline-offset:2px}
.thermo label{font-weight:800;display:flex;justify-content:space-between;align-items:baseline}
.thermo .tval{font-family:var(--font-display);font-size:1.3rem;color:var(--accent);transition:color .3s}
input[type=range]{-webkit-appearance:none;appearance:none;width:100%;height:14px;border-radius:10px;background:linear-gradient(90deg,var(--cold),var(--cool),var(--warm),var(--hot));outline:none;margin-top:8px;cursor:pointer}
input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;width:30px;height:30px;border-radius:50%;background:#fff;border:4px solid var(--accent);box-shadow:0 2px 6px rgba(0,0,0,.3);cursor:grab}
input[type=range]::-moz-range-thumb{width:26px;height:26px;border-radius:50%;background:#fff;border:4px solid var(--accent);box-shadow:0 2px 6px rgba(0,0,0,.3);cursor:grab}
input[type=range]:focus-visible{outline:3px solid var(--ink);outline-offset:4px}
.hint{font-size:.95rem;color:var(--ink-soft);margin:0}

/* life checklist (are viruses living?) */
.lifecheck{align-items:start}
.lc-panel{background:#fff;border:1px solid var(--line);border-radius:14px;padding:16px 18px}
.lc-head{font-family:var(--font-display);font-size:1.25rem;color:var(--ink-soft);margin-bottom:8px;line-height:1.2}
.lc-list{list-style:none;margin:0;padding:0}
.lc-row{display:flex;align-items:center;gap:12px;padding:9px 4px;border-bottom:1px dashed var(--line)}
.lc-row:last-child{border-bottom:none}
.lc-emoji{font-size:1.3rem;line-height:1;flex:0 0 auto}
.lc-name{flex:1;font-weight:700;color:var(--ink)}
.lc-mark{flex:0 0 auto;width:30px;height:30px;display:grid;place-items:center;border-radius:50%;font-size:1.1rem;font-weight:800}
.lc-row[data-val="no"]   .lc-mark{background:color-mix(in srgb,var(--sub-biology) 14%,#fff);color:var(--sub-biology)}
.lc-row[data-val="yes"]  .lc-mark{background:color-mix(in srgb,var(--sub-chemistry) 16%,#fff);color:var(--sub-chemistry)}
.lc-row[data-val="host"] .lc-mark{background:#f3efe7;font-size:1rem}
.lc-row[data-val="no"]   .lc-name{color:var(--ink-soft)}
.lc-score{margin-top:12px;font-size:.96rem;color:var(--ink-soft)}
.lc-score b{font-family:var(--font-display);font-size:1.25rem;color:var(--sub-biology);margin-right:2px}
.lc-btns button[data-on="true"]{background:var(--sub-biology);color:#fff;border-color:transparent}
.lc-verdict{background:#fbf0ef;border-left:4px solid var(--sub-biology);border-radius:0 12px 12px 0;padding:12px 16px;font-size:.98rem;color:#2c3650;line-height:1.5}
.lc-verdict b{color:var(--ink)}
/* elastic-launcher: energy meter + energy-transfer chain */
.energy-meter label{font-weight:800;display:flex;justify-content:space-between;align-items:baseline}
.energy-meter .eval{font-family:var(--font-display);font-size:1.2rem;color:var(--hot)}
.energy-meter .bar{height:16px;border-radius:10px;background:#f0ece3;border:1px solid var(--line);overflow:hidden;margin-top:8px}
.energy-meter .bar span{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--warm),var(--hot));transition:width .12s ease}
.chain{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.chain .link{font-weight:800;font-size:.92rem;padding:6px 12px;border-radius:30px;border:2px solid var(--line);background:#fff;color:var(--ink-soft);opacity:.5;transition:.18s}
.chain .link.is-active{opacity:1;color:#fff;background:var(--sub-physics);border-color:transparent;transform:translateY(-1px)}
.chain .arrow{color:var(--ink-soft);font-weight:800}
[data-interactive="elastic-launcher"] .seg-btns .launch{background:var(--hot);color:#fff;border-color:transparent;box-shadow:0 6px 16px -6px var(--hot)}
[data-interactive="elastic-launcher"] .seg-btns .launch:hover{transform:translateY(-1px)}

/* experiment */
.exp-grid{display:grid;grid-template-columns:.9fr 1.1fr;gap:22px;align-items:center}
@media(max-width:720px){.exp-grid{grid-template-columns:1fr}}
canvas.glass{width:100%;max-width:280px;height:300px;display:block;margin:0 auto}
canvas.plate{width:100%;max-width:280px;height:280px;display:block;margin:0 auto}
.exp-controls{display:flex;flex-wrap:wrap;gap:12px;align-items:center;margin-top:8px}
.btn{font-family:var(--font-body);font-weight:800;font-size:1rem;padding:11px 20px;border-radius:30px;border:none;cursor:pointer;background:var(--hot);color:#fff;box-shadow:0 6px 16px -6px var(--hot);transition:.18s}
.btn:hover{transform:translateY(-1px)}
.btn:focus-visible{outline:3px solid var(--ink);outline-offset:2px}
.btn.sub{background:#fff;color:var(--ink-soft);border:2px solid var(--line);box-shadow:none}
.watertemp{display:flex;align-items:center;gap:10px;font-weight:700;color:var(--ink-soft);font-size:.95rem}
.watertemp input{width:120px}
ol.steps{counter-reset:s;list-style:none;padding:0;margin:0}
ol.steps li{position:relative;padding:10px 0 10px 46px;border-bottom:1px dashed var(--line)}
ol.steps li:last-child{border-bottom:none}
ol.steps li::before{counter-increment:s;content:counter(s);position:absolute;left:0;top:9px;width:32px;height:32px;display:grid;place-items:center;border-radius:50%;background:var(--cool);color:#fff;font-family:var(--font-display);font-weight:700}
.callout{margin-top:18px;background:#fbf4ec;border-left:4px solid var(--warm);border-radius:0 12px 12px 0;padding:14px 18px}
.callout b{font-family:var(--font-display);font-size:1.35rem;color:var(--hot);display:block;margin-bottom:2px}
.safety{font-size:.9rem;color:var(--ink-soft);margin-top:10px}

/* key points */
.keypoints{background:#eef6f0;border:1px solid #cfe6d8;border-radius:var(--radius);padding:22px 26px}
.keypoints h2{color:var(--sub-chemistry);margin-top:0}
.keypoints ul{margin:0;padding-left:20px}
.keypoints li{margin:.4em 0}

/* check yourself */
.qa details{border:1px solid var(--line);border-radius:13px;margin-bottom:10px;background:#fff;overflow:hidden}
.qa summary{cursor:pointer;padding:14px 18px;font-weight:800;list-style:none;display:flex;gap:10px;align-items:flex-start}
.qa summary::-webkit-details-marker{display:none}
.qa summary::before{content:"?";flex:0 0 auto;width:26px;height:26px;border-radius:50%;background:var(--sub-physics);color:#fff;display:grid;place-items:center;font-family:var(--font-display);font-size:.95rem}
.qa details[open] summary::before{content:"✓";background:var(--sub-chemistry)}
.qa .ans{padding:0 18px 16px 54px;color:#2c3650}

/* going further / curiosity */
.further h2{color:var(--hot)}
.facts{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px;margin-top:4px}
.fact{background:var(--paper-card);border:1px solid var(--line);border-radius:16px;padding:18px 20px;position:relative;overflow:hidden}
.fact::before{content:"";position:absolute;inset:0 auto 0 0;width:5px;background:var(--fc,var(--warm))}
.fact .emoji{font-size:1.7rem;line-height:1;display:block;margin-bottom:8px}
.fact h3{margin:0 0 .25em;font-family:var(--font-display);font-weight:600;font-size:1.12rem}
.fact p{margin:0;font-size:.99rem;color:#2c3650}
.fact.sun{--fc:#F2A33C} .fact.ice{--fc:var(--cold)} .fact.steam{--fc:var(--cool)} .fact.tiny{--fc:#9B6CE7}

.facts-intro{font-size:1.08rem;color:#2c3650;margin-bottom:1.1em}
.bonus{margin-top:22px;border-top:2px dashed var(--line);padding-top:22px}
.bonus .tag{color:var(--hot)}
.bonus h2{margin-top:.1em}

/* pager */
#pager{display:flex;gap:14px;justify-content:space-between;margin:34px 0 0;flex-wrap:wrap}
.pager__btn{flex:1 1 240px;text-decoration:none;border:1px solid var(--line);border-radius:14px;padding:14px 18px;background:#fff;color:var(--ink);transition:.18s}
.pager__btn:hover{box-shadow:var(--shadow);transform:translateY(-1px)}
.pager__btn span{display:block;font-size:.85rem;color:var(--ink-soft);font-weight:700}
.pager__btn b{font-family:var(--font-display);font-weight:600}
.pager__next{text-align:right}

footer{padding:36px 26px 60px;color:var(--ink-soft);font-size:.95rem;text-align:center}

/* ============================================================
   RESPONSIVE  —  off-canvas sidebar
   ============================================================ */
@media(max-width:880px){
  body{display:block}
  .sidebar{position:fixed;left:0;top:0;height:100vh;width:var(--sidebar-w);transform:translateX(-100%);transition:transform .25s ease;z-index:60;box-shadow:0 0 60px rgba(0,0,0,.2)}
  body.nav-open .sidebar{transform:none}
  .content{width:100%}
  .navtoggle{display:grid;place-items:center;position:fixed;top:14px;left:14px;z-index:70;width:46px;height:46px;border-radius:12px;border:1px solid var(--line);background:#fff;font-size:1.4rem;cursor:pointer;box-shadow:var(--shadow)}
  body.nav-open .navbackdrop{display:block;position:fixed;inset:0;background:rgba(27,37,56,.4);z-index:55}
  .hero{padding-top:74px}
}

@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto;transition:none!important}}


/* ============================================================
   RUNESTONE HALL — structural overrides (PART 3 of the re-skin)
   ============================================================ */

/* type system: Young Serif headings (single 400 weight), Hanken body */
body{font-family:var(--font-body);}
h1,h2{font-family:var(--font-display);font-weight:400;letter-spacing:-.01em;}
h3{font-family:var(--font-body);font-weight:800;}
.sidebar__title{font-family:var(--font-display);font-weight:400;}

/* hero: constrain to the same centred 880px column as the body (.wrap),
   so the header content lines up with the sections below it */
.hero{max-width:880px;margin-inline:auto;}

/* section eyebrow (.tag) and hero eyebrow — was Caveat, now serif / caps */
.tag{font-family:var(--font-display);font-size:1.15rem;color:var(--gold-deep);}
.eyebrow{
  font-family:var(--font-body);font-size:.82rem;font-weight:700;
  letter-spacing:.08em;text-transform:uppercase;color:var(--accent);
}
.sidebar__sub{font-family:var(--font-body);font-weight:700;font-size:.62rem;
  letter-spacing:.14em;text-transform:uppercase;color:var(--gold);}
.dtable caption{font-family:var(--font-body);font-weight:700;text-transform:uppercase;
  letter-spacing:.05em;font-size:.8rem;color:var(--ink-soft);}
.callout b,.lc-head,.keypoints h2{font-family:var(--font-display);}
.navlink__label{font-family:var(--font-display);color:inherit;}

/* cards: 2px warm border + soft shadow */
.card{border:2px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);}

/* ----- SIDEBAR goes dark (the mead hall) ----- */
.sidebar{
  background:linear-gradient(180deg,var(--hall-1),var(--hall-2));
  color:#C2D0D8;border-right:none;
}
.sidebar__brand{
  display:grid;grid-template-columns:auto 1fr;column-gap:12px;align-items:center;
  border-bottom:1px solid rgba(255,255,255,.10);
}
.sidebar__brand::before{
  content:"";grid-row:span 2;width:42px;height:42px;border-radius:12px;
  background:#34505E url("../img/edda-mascot.png") center/cover no-repeat;
  background-position:50% 35%;border:1px solid rgba(255,255,255,.12);
}
.sidebar__title{color:#fff;align-self:end;}
.sidebar__sub{align-self:start;}
.col__hd:hover{background:rgba(255,255,255,.06);}
.col__chev{color:#7F94A0;}

/* subject row: dim when collapsed, white when open */
.col[data-level="subject"] > .col__hd{color:#DCE6EB;}
.col[data-level="subject"]:not([data-collapsed]) > .col__hd{color:#fff;}

/* stage row */
.col[data-level="stage"] > .col__hd{color:#8FA3AE;}
.col[data-level="stage"]{border-left-color:rgba(255,255,255,.10);}

/* chapter row: dim when collapsed, brighter when open */
.col[data-level="chapter"] > .col__hd{color:#7F94A0;}
.col[data-level="chapter"]:not([data-collapsed]) > .col__hd{color:#DCE6EB;}
.col--marker .col__name{color:#7F94A0;}
.col--marker .col__hd--static{color:#7F94A0;}

/* chapter number badge: grey by default, subject-tinted only on the open chapter */
.col__no{background:rgba(255,255,255,.06);color:#7F94A0;}
.col[data-level="chapter"]:not([data-collapsed]) > .col__hd .col__no{
  background:color-mix(in srgb,var(--sub) 26%,transparent);
  color:color-mix(in srgb,var(--sub) 48%,#fff);
}

/* topic links */
.navlink{color:#94A7B2;}
.navlink::before{background:rgba(255,255,255,.22);}
.navlink:hover{background:rgba(255,255,255,.06);color:#fff;}
.navlink.is-active{
  background:rgba(226,169,62,.14);color:#fff;font-weight:800;
  box-shadow:inset 3px 0 0 var(--gold);
}
.navlink.is-active::before{display:none;}
.navlink.is-active .navlink__label{color:var(--gold);}
.navlink--soon{color:#94A7B2;}
.navlink--soon em{color:#7F94A0;border-color:rgba(255,255,255,.18);}

/* ----- buttons ----- */
.btn{background:var(--gold);color:var(--ink);box-shadow:0 12px 24px -12px rgba(226,169,62,.8);}
.btn.sub{background:#fff;color:var(--ink-soft);border:2px solid var(--line);box-shadow:none;}

/* ----- interactive sim panel ----- */
canvas.box,.figure-svg{background:radial-gradient(120% 120% at 50% 0%,#16324A,#0F1626);}
.state-flash{font-family:var(--font-display);}
.seg-btns button{border:2px solid var(--line);border-radius:13px;}
/* the .solid/.liquid/.gas active fills already read --cold/--cool/--hot, now remapped */

/* ----- data tables ----- */
.dtable thead th{background:#F6F1E6;color:var(--ink);}

/* ----- key points panel (chemistry-tinted) ----- */
.keypoints{background:#EFF4E8;border:2px solid #D8E5C6;}
.keypoints h2{color:#56792F;}

/* ----- Q&A accordions ----- */
.qa details{border:2px solid var(--line);border-radius:14px;}
.qa summary::before{background:var(--sub-physics);font-family:var(--font-display);}
.qa details[open] summary::before{background:var(--sub-chemistry);}

/* ----- “going further” fact cards ----- */
.fact{border:2px solid var(--line);border-radius:18px;}
.fact h3{font-family:var(--font-display);font-weight:400;}

/* ----- pager ----- */
.pager__btn{border:2px solid var(--line);border-radius:16px;}
.pager__btn b{font-family:var(--font-display);font-weight:400;}