/* ppm·ail·me — instrument aesthetic. Cool airy ground, ink petrol, mono readouts.
   Band colors are DATA (CO2 bands), never decoration. */
:root{
  --air:#F3F7F8; --card:#FFFFFF; --ink:#122229; --dim:#4E656D; --line:#D3DFE1;
  --tick:#8FA6AC; --act:#0C607A; --act-ink:#0A4C61;
  --fresh:#1F7A61; --warn:#A96F14; --bad:#A63D28;
  --fresh-bg:#DCEFE7; --warn-bg:#F5E8CC; --bad-bg:#F3DDD6;
  --shadow:0 1px 2px rgba(18,34,41,.06),0 8px 24px -12px rgba(18,34,41,.18);
  --r:14px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--air);color:var(--ink);
  font:400 1.03rem/1.65 "IBM Plex Sans",system-ui,sans-serif;
  -webkit-font-smoothing:antialiased}
h1,h2,h3{font-family:"Space Grotesk",system-ui,sans-serif;line-height:1.15;letter-spacing:-.015em}
h1{font-size:clamp(1.9rem,4.5vw,2.9rem);font-weight:700;margin:.4rem 0 1rem}
h2{font-size:clamp(1.35rem,2.6vw,1.75rem);font-weight:700;margin:2.6rem 0 .8rem}
h3{font-size:1.12rem;font-weight:700;margin:1.8rem 0 .5rem}
p{margin:.8rem 0}
a{color:var(--act);text-underline-offset:3px}
a:hover{color:var(--act-ink)}
:focus-visible{outline:2.5px solid var(--act);outline-offset:2px;border-radius:3px}
code,.mono{font-family:"IBM Plex Mono",ui-monospace,monospace}
.wrap{max-width:46rem;margin:0 auto;padding:0 1.2rem}
.wrap-wide{max-width:74rem;margin:0 auto;padding:0 1.2rem}
.small{font-size:.86rem;color:var(--dim)}
.eyebrow{font-family:"IBM Plex Mono",monospace;font-size:.76rem;letter-spacing:.14em;
  text-transform:uppercase;color:var(--act);margin:0 0 .2rem}
.lede{font-size:1.16rem;line-height:1.6;color:#2A3F48;max-width:38rem}
.note{background:var(--card);border-left:4px solid var(--act);border-radius:0 10px 10px 0;
  padding:.9rem 1.1rem;font-size:.93rem;box-shadow:var(--shadow)}
.byline{margin:2rem 0 -1.4rem}

/* header / footer */
.site-head{border-bottom:1px solid var(--line);background:rgba(243,247,248,.92);
  backdrop-filter:blur(8px);position:sticky;top:0;z-index:50}
.site-head .wrap-wide{display:flex;align-items:center;justify-content:space-between;
  gap:1rem;padding-top:.7rem;padding-bottom:.7rem}
.wordmark{font-family:"IBM Plex Mono",monospace;font-weight:500;font-size:1.06rem;
  color:var(--ink);text-decoration:none;letter-spacing:.01em;white-space:nowrap}
.wordmark i{font-style:normal;color:var(--act);font-weight:700}
.site-nav{display:flex;gap:1.05rem;flex-wrap:wrap;font-size:.9rem}
.site-nav a{text-decoration:none;color:var(--dim);font-weight:600}
.site-nav a:hover,.site-nav a[aria-current]{color:var(--act-ink)}
.site-foot{border-top:1px solid var(--line);margin-top:4.5rem;padding:2.4rem 0 3rem;background:#EBF1F2}
.site-foot .cols{display:grid;grid-template-columns:1.2fr 1fr;gap:2rem}
.site-foot .motto{font-family:"Space Grotesk",sans-serif;font-weight:700;font-size:1.05rem;margin-bottom:.4rem}
.site-foot a{color:var(--dim)}

/* THE GAUGE — signature instrument */
.gauge{position:relative;margin:2.6rem 0 1.2rem;padding-top:2.4rem}
.g-bands{display:flex;height:16px;border-radius:8px;overflow:hidden;gap:2px;background:var(--air)}
.g-b{flex:1 1 33.33%}
.g-fresh{background:var(--fresh)}.g-warn{background:#D19928}.g-bad{background:#C1543C}
.g-ticks{display:flex;justify-content:space-between;margin-top:.35rem;
  font-family:"IBM Plex Mono",monospace;font-size:.72rem;color:var(--tick)}
.g-ticks span:nth-child(2){transform:translateX(-33%)}
.g-ticks span:nth-child(3){transform:translateX(-25%)}
.g-needle{position:absolute;top:0;transform:translateX(-50%);text-align:center;z-index:2}
.g-val{font-family:"IBM Plex Mono",monospace;font-size:.8rem;font-weight:500;
  background:var(--ink);color:#fff;padding:.15rem .5rem;border-radius:6px;white-space:nowrap}
.g-pin{display:block;width:2.5px;height:1.35rem;background:var(--ink);margin:.15rem auto 0}
.g-cap{font-size:.85rem;color:var(--dim);margin:.7rem 0 0}

/* readout (monitor face) */
.readout{background:var(--card);border:1px solid var(--line);border-radius:var(--r);
  box-shadow:var(--shadow);padding:1.4rem 1.6rem;display:inline-block;min-width:16rem}
.r-label{font-family:"IBM Plex Mono",monospace;font-size:.72rem;letter-spacing:.12em;color:var(--tick)}
.r-val{font-family:"IBM Plex Mono",monospace;font-weight:500;font-size:clamp(3.2rem,7vw,4.6rem);
  line-height:1.05;letter-spacing:-.02em}
.r-val .r-unit{font-size:1.1rem;color:var(--dim);margin-left:.4rem;letter-spacing:0}
.r-band{font-family:"IBM Plex Mono",monospace;font-size:.8rem;font-weight:500;margin-top:.2rem;
  display:inline-block;padding:.12rem .55rem;border-radius:6px}
.band-fresh{color:var(--fresh);background:var(--fresh-bg)}
.band-warn{color:var(--warn);background:var(--warn-bg)}
.band-bad{color:var(--bad);background:var(--bad-bg)}
.num{font-family:"IBM Plex Mono",monospace;font-weight:500}

/* hero */
.hero{padding:3.4rem 0 1rem}
.hero-grid{display:grid;grid-template-columns:auto 1fr;gap:2.6rem;align-items:center}
.btn{display:inline-block;background:var(--act);color:#fff;text-decoration:none;font-weight:600;
  font-size:.95rem;padding:.65rem 1.15rem;border-radius:10px;border:0;cursor:pointer}
.btn:hover{background:var(--act-ink);color:#fff}
.btn-quiet{background:transparent;color:var(--act);border:1.5px solid var(--line);font-family:inherit}
.btn-quiet:hover{background:var(--card);color:var(--act-ink)}
.cta-row{display:flex;gap:.7rem;flex-wrap:wrap;margin-top:1.3rem}

/* cards */
.card-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(15rem,1fr));gap:1.1rem;margin:1.6rem 0}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);
  padding:1.15rem 1.25rem;box-shadow:var(--shadow)}
.card h3{margin:.2rem 0 .4rem}
.card h3 a{text-decoration:none;color:var(--ink)}
.card h3 a:hover{color:var(--act-ink)}
.card p{font-size:.92rem;color:var(--dim);margin:.3rem 0 .6rem}
.card .go a{font-size:.88rem;font-weight:600;text-decoration:none}
.k-chip{font-family:"IBM Plex Mono",monospace;font-size:.72rem;letter-spacing:.1em;
  text-transform:uppercase;color:var(--tick)}

/* tables */
.tbl-scroll{overflow-x:auto;margin:1.2rem 0;border-radius:12px;box-shadow:var(--shadow)}
table{border-collapse:collapse;width:100%;background:var(--card);font-size:.93rem;min-width:34rem}
th{font-family:"Space Grotesk",sans-serif;text-align:left;font-size:.85rem;
  background:#E5EDEF;padding:.6rem .8rem;white-space:nowrap}
td{padding:.65rem .8rem;border-top:1px solid var(--line);vertical-align:top}
td.ppm{font-family:"IBM Plex Mono",monospace;font-weight:500;white-space:nowrap}
tr.b-fresh td.ppm{color:var(--fresh)} tr.b-warn td.ppm{color:var(--warn)} tr.b-bad td.ppm{color:var(--bad)}
.checkline{list-style:none;padding:0}
.checkline li{padding:.3rem 0 .3rem 1.7rem;position:relative}
.checkline li::before{content:"\2713";position:absolute;left:.2rem;color:var(--fresh);font-weight:700}

/* calculator */
.calc{background:var(--card);border:1px solid var(--line);border-radius:var(--r);
  box-shadow:var(--shadow);padding:1.5rem 1.6rem;margin:1.8rem 0}
.calc label{display:block;font-weight:600;font-size:.92rem;margin:.9rem 0 .25rem}
.calc input[type=number]{font:inherit;font-family:"IBM Plex Mono",monospace;
  padding:.5rem .7rem;border:1.5px solid var(--line);border-radius:9px;width:9rem;background:var(--air)}
.calc select{font:inherit;font-family:"IBM Plex Mono",monospace;padding:.5rem .7rem;
  border:1.5px solid var(--line);border-radius:9px;width:auto;max-width:100%;background:var(--air)}
.calc .row{display:flex;gap:1.4rem;flex-wrap:wrap}
.calc .seg{display:inline-flex;border:1.5px solid var(--line);border-radius:9px;overflow:hidden}
.calc .seg button{font:600 .88rem "IBM Plex Sans",sans-serif;border:0;background:transparent;
  padding:.45rem .9rem;cursor:pointer;color:var(--dim)}
.calc .seg button[aria-pressed=true]{background:var(--act);color:#fff}
.result{margin-top:1.4rem;padding:1.1rem 1.3rem;background:var(--air);border-radius:12px}
.result .r-big{font-family:"IBM Plex Mono",monospace;font-size:2.3rem;font-weight:500;line-height:1.2}
.result .r-big small{font-size:1rem;color:var(--dim)}
.formula{font-family:"IBM Plex Mono",monospace;font-size:.84rem;background:#E5EDEF;
  padding:.7rem 1rem;border-radius:10px;overflow-x:auto}

/* stats & callouts */
.stat-row{display:flex;gap:1.4rem;flex-wrap:wrap;margin:1.6rem 0}
.stat{background:var(--card);border:1px solid var(--line);border-radius:var(--r);
  box-shadow:var(--shadow);padding:1rem 1.2rem;flex:1 1 12rem;max-width:18rem}
.stat b{display:block;font-family:"IBM Plex Mono",monospace;font-size:1.9rem;font-weight:500}
.stat span{font-size:.85rem;color:var(--dim)}
.co-warn{background:var(--bad-bg);border-left:4px solid var(--bad);border-radius:0 10px 10px 0;
  padding:.95rem 1.15rem;font-size:.95rem}
.caveat{background:var(--card);border:1.5px dashed var(--tick);border-radius:var(--r);
  padding:1rem 1.3rem;font-size:.93rem}
.caveat h3{margin-top:.2rem}

/* share row */
.share-row{display:flex;align-items:center;gap:.55rem;flex-wrap:wrap;margin-top:3rem;
  padding-top:1.2rem;border-top:1px solid var(--line)}
.share-lbl{font-size:.84rem;color:var(--dim);margin-right:.3rem}
.share-row a,.share-row button{font:600 .84rem "IBM Plex Sans",sans-serif;color:var(--act);
  background:var(--card);border:1px solid var(--line);border-radius:8px;
  padding:.35rem .7rem;text-decoration:none;cursor:pointer}
.share-row a:hover,.share-row button:hover{color:var(--act-ink);border-color:var(--tick)}

/* wordmark story */
.name-story{display:flex;gap:.6rem;align-items:baseline;flex-wrap:wrap;
  font-family:"IBM Plex Mono",monospace;font-size:clamp(1.2rem,3.4vw,2rem);margin:.8rem 0}
.name-story .seg-w{background:var(--card);border:1px solid var(--line);border-radius:10px;
  padding:.25rem .7rem;box-shadow:var(--shadow)}
.name-story .g{color:var(--dim);font-size:.8em}

@media(max-width:52rem){
  .hero-grid{grid-template-columns:1fr;gap:1.8rem}
  .site-foot .cols{grid-template-columns:1fr}
}
@media(max-width:36rem){
  .site-nav{gap:.7rem;font-size:.82rem}
  .wrap,.wrap-wide{padding:0 1rem}
  table{min-width:28rem}
}
@media print{
  .site-head,.site-foot,.share-row,.no-print{display:none!important}
  body{background:#fff}
}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}

/* figures: photos & charts */
.fig-photo{margin:2.2rem 0}
.fig-photo img{width:100%;height:auto;border-radius:var(--r);box-shadow:var(--shadow);display:block}
.fig-photo figcaption,.chart figcaption{font-size:.84rem;color:var(--dim);margin-top:.55rem;line-height:1.5}
.chart{background:var(--card);border:1px solid var(--line);border-radius:var(--r);
  box-shadow:var(--shadow);padding:1.1rem 1.2rem 1rem;margin:2.2rem 0}
.chart svg{width:100%;height:auto;display:block}
.air-band{margin:3rem 0 1rem;position:relative}
.air-band img{width:100%;height:clamp(14rem,32vw,22rem);object-fit:cover;border-radius:var(--r);
  display:block;box-shadow:var(--shadow)}
.air-band .ab-tag{position:absolute;left:1.1rem;bottom:1.1rem;background:rgba(18,34,41,.78);color:#fff;
  font-family:"IBM Plex Mono",monospace;font-size:.8rem;padding:.35rem .7rem;border-radius:8px;backdrop-filter:blur(4px)}
.card img.thumb{width:100%;height:8.5rem;object-fit:cover;border-radius:10px;margin:.45rem 0 .55rem;display:block}
.presets{display:flex;gap:.5rem;align-items:center;flex-wrap:wrap;margin-bottom:.4rem}
.presets .btn-quiet{border-radius:9px;padding:.4rem .8rem;cursor:pointer}