:root{
  --paper:#f3efe8;--paper-2:#ebe5d9;--ink:#0f2233;--night:#0c0b1f;--muted:#5b6475;--orange:#c2621f;--gold:#f08a3c;--mist:#ffd49a;--line:#e2dccf;
  --font:'IBM Plex Sans',system-ui,-apple-system,sans-serif;--serif:'Newsreader',Georgia,serif;--mono:'IBM Plex Mono',ui-monospace,Menlo,monospace;
  --gutter:clamp(16px,4.2vw,54px);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:90px}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--font);line-height:1.6;font-size:17px;overflow-x:hidden}
img{max-width:100%;height:auto;display:block}
a{color:inherit}
h1,h2,h3,p{margin:0}
h1,h2,h3{font-family:var(--serif);font-weight:400;line-height:1.05;letter-spacing:-.01em}
h1{font-size:clamp(40px,6.4vw,84px);letter-spacing:-.025em}
h2{font-size:clamp(30px,3.8vw,52px)}
h3{font-size:clamp(22px,2vw,28px)}
em{font-style:italic;color:var(--orange)}
.skip{position:absolute;left:-999px;top:8px;background:var(--ink);color:#fff;padding:10px 16px;z-index:100}
.skip:focus{left:8px}
:focus-visible{outline:3px solid #c8843d;outline-offset:4px}
.wrap{max-width:1240px;margin:0 auto;padding:0 var(--gutter)}
.eyebrow{font-family:var(--mono);font-size:11.5px;letter-spacing:.18em;font-weight:500;margin-bottom:16px;color:var(--orange)}
.eyebrow.light{color:#e3ddcf}
.lead{font-size:19px;color:var(--muted);max-width:640px;margin-top:22px}
.lead.light{color:#e9e6f2}
.small-print{font-size:13px;color:var(--muted);margin-top:14px;line-height:1.55}
.small-print a,.prose a:not(.text-link),.article p a,.article li a{text-decoration:underline;text-underline-offset:3px}

/* nav */
.nav{position:sticky;top:0;z-index:40;min-height:72px;padding:10px var(--gutter);display:flex;align-items:center;justify-content:space-between;gap:20px;background:rgba(243,239,232,.95);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.brand{display:flex;align-items:center;gap:10px;font-family:Georgia,serif;font-size:23px;line-height:1;text-decoration:none;white-space:nowrap}
.brand small{display:block;font-family:var(--font);font-size:8px;letter-spacing:.16em;margin-top:6px;color:var(--muted)}
.sun{font-size:32px;color:var(--gold)}
.nav nav{display:flex;gap:26px;align-items:center;font-size:13px;font-weight:600}
.nav nav a{text-decoration:none;padding:10px 0}
.nav nav a[aria-current]{border-bottom:2px solid var(--gold)}
.nav-cta{border-bottom:1px solid #a5a2bb}

/* buttons */
.button{display:inline-flex;gap:22px;align-items:center;justify-content:space-between;padding:14px 20px;min-height:52px;font-size:14px;font-weight:600;text-decoration:none;transition:transform .15s,filter .15s}
.button.big{min-height:58px;padding:16px 24px}
.button:hover{filter:brightness(1.06);transform:translateY(-1px)}
.gold{background:linear-gradient(135deg,#f9ad4f,#ec7426);color:#1d0f03;box-shadow:0 10px 28px rgba(236,116,38,.3)}
.cream{background:#fff;color:#17324d;border:1px solid var(--line)}
.green{background:var(--ink);color:#fff}
.buy,.row-btns{display:flex;flex-wrap:wrap;gap:12px;margin-top:28px}
.text-link{display:inline-flex;gap:8px;font-size:14px;font-weight:600;padding:8px 0;border-bottom:1px solid #ffffff77;color:#f1f0f7;text-decoration:none}
.text-link.dark{color:var(--ink);border-color:#a5a2bb}

/* hero */
.hero-split{display:grid;grid-template-columns:1.15fr .85fr;gap:40px;align-items:center;padding-top:56px;padding-bottom:64px}
.hero-pic img{width:100%;max-width:480px;margin-left:auto;filter:drop-shadow(0 30px 40px rgba(15,34,51,.25))}
.hero-plain{padding-top:64px;padding-bottom:40px}
.hero-photo-wrap{position:relative;min-height:620px;display:flex;align-items:center;color:#fff;overflow:hidden}
.hero-bg{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.hero-shade{position:absolute;inset:0;background:linear-gradient(90deg,rgba(12,12,32,.92),rgba(12,12,32,.6) 50%,rgba(12,12,32,.15)),linear-gradient(0deg,rgba(9,9,26,.6),transparent 40%)}
.hero-over{position:relative;padding-top:70px;padding-bottom:70px;width:100%}
.hero-over h1{max-width:820px}
.hero-over h1 em{color:var(--mist)}
.stats{display:flex;gap:44px;flex-wrap:wrap;margin-top:36px}
.stats b{display:block;font-family:var(--serif);font-size:56px;font-weight:400;line-height:1}
.stats span{font-size:13px;color:var(--muted)}

/* sections */
.band{background:var(--paper-2);padding:80px 0}
.band.dark{background:var(--night);color:#efedf6}
.band.dark h2 em{color:var(--mist)}
.block{padding-top:80px;padding-bottom:80px}
.two{display:grid;grid-template-columns:1fr 1fr;gap:56px;align-items:start}
.prose p+p,.prose p+ul,.prose blockquote+p,.prose p+blockquote{margin-top:16px}
.ticks{list-style:none;padding:0;margin:20px 0 0}
.ticks li{padding:8px 0 8px 30px;position:relative;border-bottom:1px solid var(--line)}
.ticks li:before{content:"";position:absolute;left:4px;top:17px;width:12px;height:7px;border-left:2px solid var(--orange);border-bottom:2px solid var(--orange);transform:rotate(-45deg)}
.cards{display:grid;gap:18px;margin-top:36px}
.cards.four{grid-template-columns:repeat(4,1fr)}
.cards.three{grid-template-columns:repeat(3,1fr)}
.cards.two-col{grid-template-columns:repeat(2,1fr)}
.card{background:#fff;border:1px solid var(--line);padding:26px;display:flex;flex-direction:column;gap:12px;text-decoration:none}
.card p{color:var(--muted);font-size:15.5px;flex:1}
.card.link{transition:transform .15s,box-shadow .15s}
.card.link:hover{transform:translateY(-2px);box-shadow:0 14px 30px rgba(15,34,51,.08)}
.num{font-family:var(--mono);font-size:11px;letter-spacing:.16em;color:var(--orange)}
.big-num{font-family:var(--serif);font-size:54px;line-height:1;color:var(--orange)}
.go{font-weight:600;font-size:14px}
.more{margin-top:26px}
.center-cta{text-align:center}
.center-cta .buy{justify-content:center}

/* article pages */
.article{max-width:820px;padding-top:56px;padding-bottom:70px}
.article h2{margin-top:52px;margin-bottom:14px;font-size:clamp(28px,3vw,40px)}
.article p+p{margin-top:14px}
.article .lead{margin-bottom:10px}
.crumbs{font-size:13px;color:var(--muted);margin-bottom:22px}
.crumbs a{text-decoration:underline}
.facts{display:grid;gap:0;margin:34px 0 10px;border-top:1px solid var(--line)}
.facts div{display:grid;grid-template-columns:200px 1fr;gap:20px;padding:13px 0;border-bottom:1px solid var(--line)}
.facts dt{font-family:var(--mono);font-size:11.5px;letter-spacing:.12em;text-transform:uppercase;color:var(--muted);padding-top:3px}
.facts dd{margin:0}
.tbl{width:100%;border-collapse:collapse;margin:20px 0;font-size:15.5px;background:#fff}
.tbl th,.tbl td{padding:12px 14px;border:1px solid var(--line);text-align:left;vertical-align:top}
.tbl thead th{background:var(--ink);color:#fff;font-weight:600;font-size:13.5px}
.tbl tbody th{font-weight:600;width:34%}
.limits{margin:10px 0 24px;padding-left:20px}
.limits li{margin:8px 0;color:#3c4556}
blockquote{margin:22px 0;padding:4px 0 4px 22px;border-left:3px solid var(--gold);font-family:var(--serif);font-size:23px;line-height:1.35;font-style:italic}
blockquote cite{display:block;font-family:var(--font);font-style:normal;font-size:13px;color:var(--muted);margin-top:8px}
.band.dark blockquote cite{color:#b9b5c9}
blockquote.hard{border-color:#8a8a8a}
.quotes blockquote{font-size:20px;margin:14px 0}
.calc{margin:20px 0;padding:18px 22px;background:#fff;border:1px solid var(--line);font-size:19px}
.calc b{font-family:var(--serif);font-size:30px;font-weight:400;color:var(--orange)}
.pairs{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:20px}
.pairs figure{margin:0;background:#fff;border:1px solid var(--line)}
.pairs img{width:100%;aspect-ratio:1/1;object-fit:cover}
.pairs figcaption{font-family:var(--mono);font-size:11px;letter-spacing:.1em;padding:8px 10px;color:var(--muted)}
.pager{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:50px}
.pager a{padding:16px;border:1px solid var(--line);background:#fff;text-decoration:none;font-size:14.5px}
.pager a:last-child{text-align:right}
.steps{counter-reset:s;list-style:none;padding:0;margin:30px 0}
.steps li{counter-increment:s;position:relative;padding:4px 0 26px 64px}
.steps li:before{content:counter(s);position:absolute;left:0;top:0;width:44px;height:44px;border-radius:50%;background:var(--ink);color:#fff;display:grid;place-items:center;font-family:var(--serif);font-size:22px}
.steps h3{margin-bottom:6px}
.studies{display:grid;grid-template-columns:repeat(2,1fr);gap:16px}
.study{background:#fff;border:1px solid var(--line);padding:26px;text-decoration:none;display:flex;flex-direction:column;gap:10px;transition:transform .15s,box-shadow .15s}
.study:hover{transform:translateY(-2px);box-shadow:0 14px 30px rgba(15,34,51,.08)}
.study p{color:var(--muted);font-size:15px;flex:1}

/* faq */
.faq{padding-top:80px;padding-bottom:90px;max-width:900px}
.faq-list{margin-top:28px;border-top:1px solid var(--line)}
.faq details{border-bottom:1px solid var(--line)}
.faq summary{cursor:pointer;padding:18px 36px 18px 0;font-weight:600;font-size:17px;list-style:none;position:relative}
.faq summary::-webkit-details-marker{display:none}
.faq summary:after{content:"+";position:absolute;right:4px;top:14px;font-size:24px;color:var(--orange);font-weight:400}
.faq details[open] summary:after{content:"–"}
.faq details p{padding:0 0 20px;color:#3c4556;max-width:720px}

/* footer */
.foot{background:var(--night);color:#d9d6e6;padding:60px 0 50px}
.family{display:grid;grid-template-columns:repeat(5,1fr);gap:14px;margin:14px 0 30px}
.family a{text-decoration:none;padding:16px;border:1px solid rgba(255,255,255,.14);display:flex;flex-direction:column;gap:4px}
.family a[aria-current]{border-color:var(--gold)}
.family b{font-size:14.5px;color:#fff}
.family span{font-size:13px;color:#aaa6bd}
.fine{font-size:12.5px;color:#9e9ab2;max-width:820px}

@media (max-width:960px){
  .cards.four{grid-template-columns:repeat(2,1fr)}
  .cards.three{grid-template-columns:1fr}
  .family{grid-template-columns:repeat(2,1fr)}
}
@media (max-width:760px){
  body{font-size:16px}
  .nav{flex-wrap:wrap;gap:4px 20px}
  .nav nav{gap:16px;font-size:12.5px;flex-wrap:wrap;width:100%;overflow-x:auto}
  .nav-cta{display:none}
  .hero-split,.two,.studies,.cards.two-col,.pager{grid-template-columns:1fr}
  .hero-split{gap:10px;padding-top:30px}
  .hero-pic{order:-1}
  .hero-pic img{max-width:260px;margin:0 auto}
  .cards.four{grid-template-columns:1fr}
  .band,.block{padding-top:56px;padding-bottom:56px}
  .facts div{grid-template-columns:1fr;gap:2px}
  .button,.button.big{width:100%}
  .buy,.row-btns{flex-direction:column}
  .tbl{font-size:14px}
  .tbl th,.tbl td{padding:9px 8px}
  .tbl.compare thead th:first-child{width:28%}
  .hero-photo-wrap{min-height:560px}
  .pager a:last-child{text-align:left}
  .stats{gap:28px}
  .family{grid-template-columns:1fr}
}

/* ---- single-topic domain sites ---- */
.sec{padding-top:64px;padding-bottom:64px}
.sec.alt{background:var(--paper-2)}
.sec .stack h2{margin-bottom:22px}
.tw{overflow-x:auto;margin:16px 0}
.tw .tbl{margin:0;min-width:520px}
.nums{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:1px;background:var(--line);border:1px solid var(--line)}
.nums div{background:#fff;padding:20px}
.nums b{display:block;font-family:var(--serif);font-weight:400;font-size:40px;line-height:1;color:var(--orange);margin-bottom:8px}
.nums span{font-size:14.5px;color:var(--muted)}
.swatches{display:flex;flex-wrap:wrap;gap:10px;margin:8px 0 14px}
.swatches span{display:inline-flex;align-items:center;gap:8px;padding:8px 14px 8px 10px;background:#fff;border:1px solid var(--line);font-size:14px;font-weight:600}
.swatches span:before{content:"";width:18px;height:18px;border-radius:50%;background:var(--c);border:1px solid rgba(0,0,0,.15)}
.qa input{width:100%;max-width:560px;font:inherit;padding:14px 16px;border:1px solid var(--line);background:#fff}
.qa .small{font-size:13px;color:var(--muted);margin:10px 0}
.qa details{border-bottom:1px solid var(--line)}
.qa summary{cursor:pointer;padding:14px 0;font-weight:600}
.qa details p{padding-bottom:14px;color:#3c4556}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}
.calc-box{display:grid;gap:18px;background:#fff;border:1px solid var(--line);padding:24px;max-width:620px}
.calc-box label{display:block;font-weight:600;font-size:15px;margin-bottom:4px}
.calc-box input{width:70%;vertical-align:middle;accent-color:var(--orange)}
.calc-box b{font-family:var(--serif);font-size:28px;font-weight:400;margin-left:12px;color:var(--orange)}
.calc-box .out p{font-size:17px;margin:4px 0}
.family.small{grid-template-columns:repeat(4,1fr)}
.study h3{font-size:22px}
/* water guide theme */
body.water{--paper:#f2f6f8;--paper-2:#e3edf1;--ink:#0d2a3a;--night:#0b2230;--orange:#0f6f8f;--gold:#2aa7c9;--mist:#9fe0f2;--line:#d5e2e8}
body.water .gold{background:linear-gradient(135deg,#38b6d8,#0f7fa3);color:#fff;box-shadow:0 10px 28px rgba(15,111,143,.25)}
body.water .sun{color:#2aa7c9}
@media (max-width:760px){.nums{grid-template-columns:1fr 1fr}.family.small{grid-template-columns:1fr}.calc-box input{width:100%}}
body.water .nav{background:rgba(242,246,248,.95)}
.prose a.study,.prose a.card{text-decoration:none}