/* IndoorAirLab — shared styles */
:root{
  --paper:#F5F8F9; --card:#FFFFFF; --ink:#12303A; --ink-2:#4A6470; --line:#D5E1E5;
  --teal:#0F6E74; --teal-d:#0A5257; --sky:#D9EEF2; --mist:#EEF6F7; --amber:#E9A23B; --amber-l:#FCF1DE;
  --good:#1F7A4D; --good-l:#E2F3EA; --warn:#9A5B00; --weak:#8A3B3B; --weak-l:#F7E6E6;
  --r-lg:22px; --r-md:14px; --r-sm:8px;
  --head:'Bricolage Grotesque','Segoe UI',Arial,sans-serif;
  --body:'Source Sans 3','Segoe UI',Arial,Helvetica,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--body);font-size:18px;line-height:1.6;-webkit-font-smoothing:antialiased}
img,svg{max-width:100%}
a{color:var(--teal)}
a:hover{color:var(--teal-d)}
:focus-visible{outline:3px solid var(--amber);outline-offset:2px;border-radius:4px}
h1,h2,h3{font-family:var(--head);line-height:1.15;letter-spacing:-.01em;margin:0 0 .5em}
h1{font-size:clamp(2.2rem,5vw,3.6rem);font-weight:800}
h2{font-size:clamp(1.6rem,3vw,2.2rem);font-weight:750}
h3{font-size:1.2rem;font-weight:700}
p{margin:0 0 1em}
.wrap{max-width:1140px;margin:0 auto;padding:0 20px}
.narrow{max-width:760px}
.muted{color:var(--ink-2)}
.small{font-size:.9rem}
.skip{position:absolute;left:-999px}.skip:focus{left:12px;top:12px;background:#fff;padding:8px 12px;z-index:99}

/* disclosure bar */
.disclose{background:var(--ink);color:#DCEBEF;font-size:.85rem;text-align:center;padding:7px 16px}
.disclose a{color:#fff}

/* header */
.site-head{background:rgba(255,255,255,.92);backdrop-filter:blur(8px);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:40}
.site-head .wrap{display:flex;align-items:center;justify-content:space-between;height:68px;gap:16px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);font-family:var(--head);font-weight:800;font-size:1.3rem}
.brand svg{width:34px;height:34px;flex:none}
.brand span b{color:var(--teal);font-weight:800}
.nav{display:flex;gap:26px;align-items:center}
.nav a{color:var(--ink);text-decoration:none;font-weight:600;font-size:.98rem}
.nav a:hover{color:var(--teal)}
.nav .btn{color:#fff}
.menu-btn{display:none;background:none;border:1px solid var(--line);border-radius:10px;padding:8px 12px;font:600 .95rem var(--body);color:var(--ink)}
@media (max-width:860px){
  .nav{display:none;position:absolute;top:68px;left:0;right:0;background:#fff;border-bottom:1px solid var(--line);flex-direction:column;align-items:flex-start;padding:16px 20px;gap:14px}
  .nav.open{display:flex}
  .menu-btn{display:block}
}

/* buttons */
.btn{display:inline-block;background:var(--teal);color:#fff;text-decoration:none;font-weight:700;padding:13px 22px;border-radius:999px;border:2px solid var(--teal);font-size:1rem}
.btn:hover{background:var(--teal-d);border-color:var(--teal-d);color:#fff}
.btn.ghost{background:transparent;color:var(--teal)}
.btn.ghost:hover{background:var(--mist);color:var(--teal-d)}
.btn.sm{padding:8px 16px;font-size:.92rem}

/* hero */
.hero{padding:56px 0 40px;background:linear-gradient(180deg,#fff 0%,var(--paper) 100%);border-bottom:1px solid var(--line)}
.hero .wrap{display:grid;grid-template-columns:1.05fr .95fr;gap:40px;align-items:center}
.hero p.lead{font-size:1.2rem;color:var(--ink-2);max-width:34em}
.hero .actions{display:flex;flex-wrap:wrap;gap:12px;margin-top:22px}
.room{background:var(--card);border:1px solid var(--line);border-radius:var(--r-lg);padding:14px}
.room figcaption{font-size:.85rem;color:var(--ink-2);padding:6px 6px 0}
@media (max-width:860px){.hero .wrap{grid-template-columns:1fr}.hero{padding-top:36px}}

/* particle animation: one orchestrated moment */
.pt{fill:#7D8E95;opacity:.75}
.pt.fine{fill:#A58A63}
@media (prefers-reduced-motion:no-preference){
  .pt{animation:clear 2.6s ease-in forwards}
  .fan{animation:spin 1.2s linear 6;transform-origin:center;transform-box:fill-box}
  .clean-air{animation:breathe 2.6s ease-out forwards;opacity:0}
}
@media (prefers-reduced-motion:reduce){.pt{opacity:.15}}
@keyframes clear{0%{opacity:.75}100%{opacity:.08;transform:translate(var(--dx,40px),var(--dy,20px))}}
@keyframes spin{to{transform:rotate(360deg)}}
@keyframes breathe{to{opacity:1}}

/* picker */
.picker{padding:34px 0 8px}
.picker h2{font-size:1.4rem}
.chips{display:flex;flex-wrap:wrap;gap:10px}
.chip{display:inline-flex;align-items:center;gap:8px;background:#fff;border:1.5px solid var(--line);border-radius:999px;padding:9px 16px;text-decoration:none;color:var(--ink);font-weight:600}
.chip:hover{border-color:var(--teal);color:var(--teal)}
.chip svg{width:20px;height:20px;stroke:var(--teal);flex:none}

/* sections */
section.block{padding:56px 0}
.section-head{max-width:640px;margin-bottom:28px}

/* topic tiles */
.topics{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
.topic{background:#fff;border:1px solid var(--line);border-radius:var(--r-md);padding:20px;text-decoration:none;color:var(--ink);display:flex;flex-direction:column;gap:6px;min-height:170px}
.topic .ic{width:46px;height:46px;border-radius:12px;background:var(--mist);display:grid;place-items:center;margin-bottom:6px}
.topic .ic svg{width:26px;height:26px;stroke:var(--teal)}
.topic p{font-size:.95rem;color:var(--ink-2);margin:0}
.topic .status{margin-top:auto;font-size:.85rem;font-weight:700;color:var(--ink-2)}
.topic.live{grid-column:span 2;grid-row:span 2;background:var(--ink);color:#fff;border-color:var(--ink);padding:28px}
.topic.live h3{font-size:1.7rem}
.topic.live p{color:#C9DDE2;font-size:1.05rem}
.topic.live .ic{background:rgba(255,255,255,.1)}
.topic.live .ic svg{stroke:#fff}
.topic.live .status{color:var(--amber)}
.topic.live ul{margin:10px 0 18px;padding-left:18px;color:#E6F1F3;font-size:1.02rem}
.topic.live li{margin-bottom:8px}
.topic.live a{color:#fff;text-decoration-color:rgba(255,255,255,.4);text-underline-offset:3px}
.topic.live a:hover{color:var(--amber)}
a.topic:hover{border-color:var(--teal)}
a.topic.live:hover{border-color:var(--amber)}
.topic:target{outline:3px solid var(--amber)}
@media (max-width:980px){.topics{grid-template-columns:repeat(2,1fr)}}
@media (max-width:560px){.topics{grid-template-columns:1fr}.topic.live{grid-column:auto;grid-row:auto}}

/* guide list */
.guides{display:grid;grid-template-columns:repeat(2,1fr);gap:18px}
.guide{display:grid;grid-template-columns:96px 1fr;gap:16px;align-items:start;background:#fff;border:1px solid var(--line);border-radius:var(--r-md);padding:16px;text-decoration:none;color:var(--ink)}
.guide:hover{border-color:var(--teal)}
.guide .thumb{width:96px;height:96px;border-radius:12px;display:grid;place-items:center}
.guide .thumb svg{width:44px;height:44px;stroke:var(--ink)}
.guide h3{margin-bottom:4px;font-size:1.12rem}
.guide p{font-size:.95rem;color:var(--ink-2);margin:0}
@media (max-width:760px){.guides{grid-template-columns:1fr}}

/* calculator */
.calc{background:#fff;border:1px solid var(--line);border-radius:var(--r-lg);padding:26px;display:grid;grid-template-columns:300px 1fr;gap:28px}
.calc label{font-weight:700;display:flex;justify-content:space-between;margin-bottom:6px}
.calc output{color:var(--teal);font-weight:700}
.calc input[type=range]{width:100%;accent-color:var(--teal);margin-bottom:18px}
.calc select{width:100%;padding:10px;border:1px solid var(--line);border-radius:10px;font:inherit;background:#fff}
.results{display:grid;grid-template-columns:repeat(2,1fr);gap:14px}
.unit{border:1px solid var(--line);border-radius:var(--r-md);padding:16px;display:flex;flex-direction:column}
.unit h3{font-size:1.05rem;margin:0}
.fit{display:inline-block;align-self:flex-start;font-size:.8rem;font-weight:700;padding:3px 10px;border-radius:999px;margin:6px 0 8px}
.fit.yes{background:var(--good-l);color:var(--good)}
.fit.no{background:var(--weak-l);color:var(--weak)}
.unit dl{display:grid;grid-template-columns:1fr auto;gap:2px 10px;font-size:.92rem;margin:0 0 10px;color:var(--ink-2)}
.unit dd{margin:0;text-align:right;color:var(--ink);font-variant-numeric:tabular-nums}
.unit .total{margin-top:auto;border-top:1px solid var(--line);padding-top:10px;display:flex;justify-content:space-between;align-items:baseline}
.unit .total strong{font-family:var(--head);font-size:1.5rem}
@media (max-width:900px){.calc{grid-template-columns:1fr}}
@media (max-width:560px){.results{grid-template-columns:1fr}}

/* trust strip */
.trust{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.trust div{border-left:3px solid var(--teal);padding-left:16px}
.trust h3{font-size:1.08rem;margin-bottom:4px}
.trust p{font-size:.95rem;color:var(--ink-2);margin:0}
@media (max-width:760px){.trust{grid-template-columns:1fr}}

/* founder */
.founder{display:grid;grid-template-columns:120px 1fr;gap:24px;align-items:center;background:var(--sky);border-radius:var(--r-lg);padding:28px}
.avatar{width:120px;height:120px;border-radius:50%;background:var(--teal);color:#fff;display:grid;place-items:center;font:800 3rem var(--head)}
@media (max-width:560px){.founder{grid-template-columns:1fr}}

/* faq */
details{background:#fff;border:1px solid var(--line);border-radius:var(--r-sm);padding:14px 18px;margin-bottom:10px}
summary{font-weight:700;cursor:pointer}
details p{margin:.6em 0 0;color:var(--ink-2)}

/* footer */
.site-foot{background:var(--ink);color:#C9DDE2;padding:48px 0 28px;margin-top:40px;font-size:.95rem}
.site-foot a{color:#fff;text-decoration:none}
.site-foot a:hover{text-decoration:underline}
.foot-cols{display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:32px}
.foot-cols h3{color:#fff;font-size:1rem}
.foot-cols ul{list-style:none;padding:0;margin:0}
.foot-cols li{margin-bottom:6px}
.site-foot .brand{color:#fff}
.legal{border-top:1px solid rgba(255,255,255,.15);margin-top:32px;padding-top:18px;font-size:.85rem}
@media (max-width:760px){.foot-cols{grid-template-columns:1fr}}

/* article */
.crumbs{font-size:.9rem;margin:28px 0 12px}
.crumbs a{text-decoration:none}
.art-head{padding-bottom:22px;border-bottom:1px solid var(--line);margin-bottom:28px}
.art-head h1{font-size:clamp(2rem,4.2vw,3rem)}
.byline{display:flex;align-items:center;gap:12px;color:var(--ink-2);font-size:.95rem}
.byline .avatar{width:40px;height:40px;font-size:1.1rem}
.art-grid{display:grid;grid-template-columns:minmax(0,1fr) 260px;gap:48px;align-items:start}
.toc{position:sticky;top:90px;background:#fff;border:1px solid var(--line);border-radius:var(--r-md);padding:18px;font-size:.95rem}
.toc h2{font-size:1rem;margin-bottom:8px}
.toc ol{margin:0;padding-left:18px}
.toc li{margin-bottom:6px}
.toc a{text-decoration:none;color:var(--ink-2)}
.toc a:hover{color:var(--teal)}
@media (max-width:980px){.art-grid{grid-template-columns:1fr}.toc{position:static;order:-1}}

/* evidence box — the signature element */
.evidence{background:#fff;border:2px solid var(--ink);border-radius:var(--r-lg);padding:22px 24px;margin-bottom:32px}
.evidence h2{font-size:1.25rem;margin-bottom:14px}
.ev-row{display:grid;grid-template-columns:1fr auto;gap:12px;align-items:center;padding:10px 0;border-top:1px solid var(--line)}
.ev-row:first-of-type{border-top:0}
.ev-claim{font-weight:600}
.ev-claim small{display:block;font-weight:400;color:var(--ink-2);font-size:.88rem}
.meter{display:flex;align-items:center;gap:8px;font-size:.85rem;font-weight:700;white-space:nowrap}
.meter i{display:inline-block;width:12px;height:12px;border-radius:3px;background:var(--line)}
.meter.s3 i{background:var(--good)} .meter.s3{color:var(--good)}
.meter.s2 i:nth-child(-n+2){background:var(--amber)} .meter.s2{color:var(--warn)}
.meter.s1 i:first-child{background:var(--weak)} .meter.s1{color:var(--weak)}
.meter.ref i{background:var(--teal)} .meter.ref{color:var(--teal)}
@media (max-width:560px){.ev-row{grid-template-columns:1fr}}

.prose{font-size:1.08rem}
.prose h2{margin-top:2em;scroll-margin-top:90px}
.prose h2:first-child{margin-top:0}
.prose ul,.prose ol{padding-left:1.3em}
.prose li{margin-bottom:.4em}
.prose table{width:100%;border-collapse:collapse;font-size:.95rem;margin:1em 0 1.5em;display:block;overflow-x:auto}
.prose th,.prose td{border:1px solid var(--line);padding:10px 12px;text-align:left;vertical-align:top}
.prose thead th{background:var(--mist);font-family:var(--head)}
.prose tbody tr:nth-child(even){background:#FAFCFD}
.prose .short{background:var(--amber-l);border-radius:var(--r-md);padding:18px 20px;margin-bottom:1.5em}
.prose .short h2{margin-top:0;font-size:1.3rem}
.prose .short p:last-child{margin:0}
.prose .sources{font-size:.92rem;color:var(--ink-2)}
.related{margin-top:48px}
.related .guides{grid-template-columns:1fr 1fr}
@media (max-width:760px){.related .guides{grid-template-columns:1fr}}
.notice{background:var(--mist);border-left:4px solid var(--teal);padding:14px 18px;border-radius:0 var(--r-sm) var(--r-sm) 0;font-size:.95rem}

/* dropdown nav (desktop hover/focus, mobile stacked) */
.dd{position:relative}
.dd-top::after{content:"";display:inline-block;width:7px;height:7px;border-right:2px solid currentColor;border-bottom:2px solid currentColor;transform:rotate(45deg);margin:0 0 3px 8px}
.dd-menu{display:none;position:absolute;top:100%;left:-14px;min-width:260px;background:#fff;border:1px solid var(--line);border-radius:12px;padding:8px;box-shadow:0 12px 30px rgba(18,48,58,.12);z-index:50}
.dd-menu a{display:block;padding:9px 12px;border-radius:8px;font-weight:600;font-size:.95rem}
.dd-menu a:hover{background:var(--mist)}
.dd:hover .dd-menu,.dd:focus-within .dd-menu{display:block}
.dd::before{content:"";position:absolute;left:0;right:0;top:100%;height:12px}
@media (max-width:860px){
  .dd{width:100%}
  .dd-top::after{display:none}
  .dd-menu{display:block;position:static;border:0;box-shadow:none;padding:4px 0 0 12px;min-width:0}
  .dd-menu a{padding:6px 0;font-weight:500;color:var(--ink-2)}
}

/* hero story strip */
.story{display:flex;align-items:center;gap:12px;margin-top:22px;color:var(--ink-2);font-size:.98rem}
.story .avatar{width:42px;height:42px;font-size:1.1rem;flex:none}

/* finder */
.finder-wrap{padding:36px 0 8px}
.finder{background:var(--ink);color:#fff;border-radius:var(--r-lg);padding:32px;display:grid;grid-template-columns:1fr 1.1fr;gap:28px 40px}
.finder-intro h2{font-size:clamp(1.8rem,3.4vw,2.6rem)}
.finder-intro p{color:#C9DDE2}
.finder-form{display:grid;gap:16px}
.finder-form label{display:grid;gap:8px;font-weight:700}
.finder-form .muted{color:#9FBFC6}
.finder-form select,.finder-form input{font:inherit;padding:10px 12px;border-radius:10px;border:1px solid #2E5562;background:#fff;color:var(--ink)}
.dims{display:flex;align-items:center;gap:10px;font-weight:600}
.dims input{width:90px}
.finder-out{grid-column:1/-1;background:#fff;color:var(--ink);border-radius:var(--r-md);padding:22px 24px}
.finder-out h3{margin-bottom:6px}
.fo-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin:12px 0}
.fo-grid div{border:1px solid var(--line);border-radius:12px;padding:14px}
.fo-grid strong{display:block;font-family:var(--head);font-size:1.7rem;color:var(--teal)}
.fo-grid span{font-size:.9rem;color:var(--ink-2)}
.finder-out ul{margin:8px 0 0;padding-left:20px}
@media (max-width:860px){.finder{grid-template-columns:1fr;padding:24px}.fo-grid{grid-template-columns:1fr}}

/* resources */
.res-cols{display:grid;grid-template-columns:1fr 1fr;gap:28px}
.res{background:#fff;border:1px solid var(--line);border-radius:var(--r-md);padding:24px}
.res-head{display:flex;align-items:center;gap:14px;margin-bottom:8px}
.res-head h3{margin:0}
.res .ic{width:46px;height:46px;border-radius:12px;background:var(--mist);display:grid;place-items:center}
.res .ic svg{width:26px;height:26px;stroke:var(--teal)}
.res ul{margin:0;padding-left:20px}.res li{margin:6px 0}
@media (max-width:760px){.res-cols{grid-template-columns:1fr}}

/* article figures */
.prose figure{margin:1.4em 0 1.8em}
.prose figure img{width:100%;height:auto;border-radius:var(--r-md);border:1px solid var(--line);display:block}
.prose figcaption{font-size:.88rem;color:var(--ink-2);margin-top:8px}