/* What Delhi Breathes — breathe.sahiltayal.com
   Palette: haze #E9EAE6 · soot #23272A · clear-sky #4C7FA8 (accent) / sky ink #2F5F86 (link text, 5.6:1 on haze)
   CPCB AQI category colours are used only for data. */
:root{
  --haze:#E9EAE6; --paper:#F3F4F1; --soot:#23272A; --muted:#4A5056; --rule:#C6C9C2;
  --sky:#4C7FA8; --sky-ink:#2F5F86; --sky-wash:#DCE5EC;
  --good:#00B050; --sat:#92D050; --mod:#FFFF00; --poor:#FF9900; --vpoor:#FF0000; --sev:#C00000;
  --sans:"Public Sans",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  --mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --measure:68ch; --wide:61rem; --haze-amt:0;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%}
body{margin:0;background:var(--haze);color:var(--soot);font-family:var(--sans);font-size:1.1875rem;line-height:1.62;font-feature-settings:"kern","liga"}
img,svg{max-width:100%;height:auto}
a{color:var(--sky-ink);text-decoration-thickness:1px;text-underline-offset:.18em;text-decoration-color:var(--sky)}
a:hover{text-decoration-thickness:2px}
:focus-visible{outline:3px solid var(--sky-ink);outline-offset:3px;border-radius:2px}
.skip{position:absolute;left:1rem;top:-4rem;background:var(--soot);color:#fff;padding:.6rem 1rem;z-index:10}
.skip:focus{top:1rem}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.num{font-family:var(--mono);font-size:.88em;font-variant-numeric:tabular-nums;letter-spacing:-.01em;white-space:nowrap}

/* masthead */
.masthead{border-bottom:1px solid var(--rule)}
.mast-in{max-width:var(--wide);margin:0 auto;padding:.7rem 1rem;display:flex;flex-wrap:wrap;align-items:baseline;gap:.25rem 1rem;font-size:.9rem}
.mark{font-weight:700;color:var(--soot);text-decoration:none;letter-spacing:-.01em}
.mark:hover{text-decoration:underline}
.verse{color:var(--muted)}
.site-link{margin-left:auto;color:var(--soot);text-decoration:none}
.site-link:hover{text-decoration:underline}

main{display:block}
.crumbs{max-width:var(--wide);margin:0 auto;padding:1rem 1rem 0;font-size:.85rem;color:var(--muted)}
.crumbs ol{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:.4rem}
.crumbs li+li::before{content:"/";margin-right:.4rem;color:var(--rule)}

/* type */
h1,h2,h3{line-height:1.18;letter-spacing:-.015em;text-wrap:balance}
h1{font-size:clamp(2.1rem,1.4rem + 3.6vw,3.5rem);font-weight:700;margin:.2em 0 .35em;letter-spacing:-.025em}
h2{font-size:1.5rem;font-weight:700;margin:2.2em 0 .5em}
h3{font-size:1.2rem;font-weight:600;margin:1.8em 0 .4em}
p{margin:0 0 1em}
.prose{max-width:var(--measure)}
.prose ul,.prose ol{padding-left:1.25em}
.prose li{margin-bottom:.5em}
.lede{font-size:1.28rem;line-height:1.5;margin-bottom:1.4em}
.note{font-size:.95rem;color:var(--muted)}
q{quotes:"“" "”" "‘" "’"}
sup.fn{line-height:0;font-size:.68em;vertical-align:super;margin-left:.08em}
sup.fn a{font-family:var(--mono);text-decoration:none;padding:0 .1em;border-bottom:1px solid var(--sky)}
sup.fn.sep::before{content:",";color:var(--muted)}

/* chapter layout */
.chapter{max-width:var(--wide);margin:0 auto;padding:1.5rem 1rem 3rem}
.ch-head{max-width:var(--measure);margin-bottom:1.8rem}
.ch-num{font-size:.95rem;color:var(--muted);margin:0}
.reviewed{font-size:.9rem;color:var(--muted);margin:0}
.review-flag{background:var(--paper);border-left:4px solid var(--sky);padding:.9rem 1.1rem;font-size:1rem}
.aside-note{background:var(--paper);border-left:4px solid var(--rule);padding:.9rem 1.1rem;font-size:1rem}
.formula{background:var(--paper);padding:.8rem 1rem;overflow-x:auto;font-size:1rem}
.formula .num{white-space:normal}
details.working{margin:.5rem 0 1.5rem;font-size:1rem}
details.working summary{cursor:pointer;color:var(--sky-ink)}

/* tables */
.table-wrap{overflow-x:auto;margin:1.2rem 0 1.6rem;-webkit-overflow-scrolling:touch}
.table-wrap.tall{max-height:34rem;overflow-y:auto;border:1px solid var(--rule)}
table{border-collapse:collapse;width:100%;font-size:.95rem;line-height:1.4}
caption{text-align:left;font-weight:600;padding:0 0 .5rem;caption-side:top}
th,td{text-align:left;padding:.5rem .7rem .5rem 0;border-bottom:1px solid var(--rule);vertical-align:top}
thead th{font-weight:600;border-bottom:2px solid var(--soot);font-size:.88rem}
tbody th{font-weight:600}
.tall thead th{position:sticky;top:0;background:var(--haze)}
.tall th,.tall td{padding-left:.6rem}
.bp-table td,.month-table td{white-space:nowrap}
.us-cat{font-size:.92em}

/* category chip: swatch + name, colour never alone */
.chip{display:inline-flex;align-items:center;gap:.4em;white-space:nowrap;font-weight:600}
.chip .sw{width:.95em;height:.95em;border-radius:2px;border:1px solid rgba(35,39,42,.55);flex:none}
.c-good .sw,rect.c-good{background:var(--good);fill:var(--good)}
.c-sat .sw,rect.c-sat{background:var(--sat);fill:var(--sat)}
.c-mod .sw,rect.c-mod{background:var(--mod);fill:var(--mod)}
.c-poor .sw,rect.c-poor{background:var(--poor);fill:var(--poor)}
.c-vpoor .sw,rect.c-vpoor{background:var(--vpoor);fill:var(--vpoor)}
.c-sev .sw,rect.c-sev{background:var(--sev);fill:var(--sev)}
.plus{font-weight:700}

/* hero + haze */
.hero{max-width:var(--wide);margin:0 auto;padding:2.2rem 1rem 1rem}
.site-title{font-size:1rem;color:var(--muted);margin:0 0 .4rem}
.hero h1{max-width:16ch;font-size:clamp(2.3rem,1.3rem + 4.6vw,4.2rem);line-height:1.04}
.stand{max-width:58ch;font-size:1.22rem;line-height:1.5}
.band{margin:2rem 0 0}
.band-art{position:relative;height:clamp(5.5rem,14vw,9rem);overflow:hidden;border-radius:3px;outline:1px solid rgba(35,39,42,.25)}
.ribbon{display:block;width:100%;height:100%;filter:blur(calc(var(--haze-amt) * 5px));transform:scale(calc(1 + var(--haze-amt) * .04))}
.haze{position:absolute;inset:0;pointer-events:none;opacity:var(--haze-amt);
  background:linear-gradient(180deg,rgba(233,234,230,.92) 0%,rgba(214,216,211,.86) 45%,rgba(233,234,230,.9) 100%)}
.band figcaption{font-size:.92rem;color:var(--muted);margin-top:.6rem;max-width:var(--measure)}

.opening{max-width:var(--wide);margin:0 auto;padding:1rem 1rem 0}
.opening>*{max-width:var(--measure)}
.opening p strong{font-weight:700}
.sig{color:var(--muted)}

/* year calendar */
.year-block{max-width:var(--wide);margin:0 auto;padding:0 1rem}
.chapter .year-block{padding:0}
.year-intro{max-width:var(--measure)}
.legend{list-style:none;padding:0;margin:1rem 0;display:flex;flex-wrap:wrap;gap:.4rem 1.3rem;font-size:.92rem}
.legend li{display:flex;align-items:baseline;gap:.45rem}
.legend .cnt{color:var(--muted)}
.hm-wrap{position:relative;margin:.5rem 0 1rem;max-width:44rem}
.hm-wrap:focus-visible{outline-offset:6px}
.heatmap{display:block;width:100%;height:auto;font-family:var(--mono)}
.heatmap rect.d{stroke:rgba(35,39,42,.38);stroke-width:.75}
.heatmap rect.d.is-active{stroke:var(--soot);stroke-width:2.5}
.hm-ax{font-size:10px;fill:var(--muted)}
.hm-ann{fill:none;stroke:var(--soot);stroke-width:1.8}
.hm-tip{position:absolute;z-index:3;pointer-events:none;background:var(--soot);color:#fff;padding:.5rem .7rem;border-radius:3px;font-size:.85rem;line-height:1.35;max-width:16rem;box-shadow:0 2px 0 rgba(0,0,0,.15)}
.hm-tip .num{font-size:1em}
.hm-tip b{font-weight:600}
.ann-h{font-size:1.05rem;margin-top:1rem}
.ann-list{padding-left:1.4rem;max-width:var(--measure);font-size:1rem}
.ann-list li{margin-bottom:.4rem}
.year-links{font-size:1rem}
.data-source{font-size:.9rem;color:var(--muted);max-width:var(--measure)}

/* chapter index */
.chapters{max-width:var(--wide);margin:0 auto;padding:0 1rem 1rem}
.ch-intro{color:var(--muted)}
.chapter-index{list-style:none;padding:0;margin:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(17rem,1fr));gap:0 2.5rem;border-top:1px solid var(--rule)}
.chapter-index li{border-bottom:1px solid var(--rule);padding:1rem 0}
.chapter-index a{display:flex;gap:.8rem;text-decoration:none;color:var(--soot)}
.chapter-index a:hover .ci-t{text-decoration:underline;text-decoration-color:var(--sky)}
.ci-n{font-family:var(--mono);color:var(--sky-ink);font-size:.95rem;padding-top:.15rem;min-width:1.2rem}
.ci-t{font-weight:600;font-size:1.08rem;line-height:1.3}
.chapter-index p{margin:.35rem 0 0 2rem;font-size:.95rem;color:var(--muted);line-height:1.45}
.home-rev{max-width:var(--wide);margin:1rem auto 3rem;padding:0 1rem}

/* scale figure */
.scale{margin:1.5rem 0;max-width:40rem}
.scale svg{display:block;width:100%;background:var(--paper);border-radius:3px}
.sc-hair{fill:#C9B79C;stroke:var(--soot);stroke-width:1}
.sc-pm10{fill:var(--sky-wash);stroke:var(--soot);stroke-width:1}
.sc-pm25{fill:var(--soot)}
.sc-l{font-family:var(--mono);font-size:12px;fill:var(--soot)}
.scale figcaption{font-size:.92rem;color:var(--muted);margin-top:.5rem}

/* notes + keep exploring */
.notes{max-width:var(--measure);margin-top:3rem;border-top:2px solid var(--soot);padding-top:.5rem}
.notes h2{font-size:1.15rem;margin-top:.8rem}
.notes ol{font-size:.9rem;line-height:1.5;padding-left:1.6rem}
.notes li{margin-bottom:.7rem}
.notes li:target{background:var(--sky-wash)}
.notes .src{word-break:break-word}
.acc{color:var(--muted)}
.back{font-size:.85em;margin-left:.2rem}
.keep{max-width:var(--measure);margin-top:2.5rem;background:var(--paper);padding:1.1rem 1.3rem}
.keep h2{font-size:1.15rem;margin:0 0 .6rem}
.keep ul{list-style:none;padding:0;margin:0}
.keep li{margin-bottom:.6rem;line-height:1.4}
.ke-l{display:block;font-size:.85rem;color:var(--muted)}
.src-list{font-size:.95rem;line-height:1.5}
.src-list li{margin-bottom:.7rem}
.start li{margin-bottom:.8rem}
.start .why{display:block;font-size:.95rem;color:var(--muted)}

/* footer */
.site-foot{border-top:1px solid var(--rule);background:var(--paper);font-size:.95rem}
.foot-in{max-width:var(--wide);margin:0 auto;padding:2rem 1rem 2.5rem;display:grid;grid-template-columns:repeat(auto-fit,minmax(15rem,1fr));gap:1.5rem 2.5rem}
.foot-h{font-size:1rem;margin:0 0 .6rem}
.foot-col ol{padding-left:1.3rem;margin:0 0 1rem}
.foot-col li{margin-bottom:.3rem}
.related{list-style:none;padding:0;margin:0}
.related li{margin-bottom:.7rem}
.related span{display:block;color:var(--muted);font-size:.9rem}
.small{font-size:.85rem;color:var(--muted)}

@media (max-width:40rem){
  body{font-size:1.125rem}
  .lede{font-size:1.15rem}
  .site-link{margin-left:0;width:100%}
  th,td{padding-right:.5rem}
  .chapter-index p{margin-left:2rem}
}
@media (prefers-reduced-motion:reduce){
  *{scroll-behavior:auto!important;transition:none!important;animation:none!important}
}
@media print{
  .masthead,.site-foot,.keep,.band,.hm-tip{display:none}
  body{background:#fff}
}