:root{
  --soot:#1d1a17;
  --soot-2:#29251f;
  --soot-line:#3d372f;
  --smoke:#b9b1a6;
  --ash:#e8e6e1;
  --paper:#ffffff;
  --ink:#211e1b;
  --muted:#6a645c;
  --line:#d5d1ca;
  --ember:#e2602a;
  --ember-ink:#b2461a;
  --wa:#1faf55;
  --wa-hover:#178f45;
  --display:"Alumni Sans","Arial Narrow",sans-serif;
  --text:"Golos Text",system-ui,-apple-system,"Segoe UI",sans-serif;
  --ease:cubic-bezier(.16,1,.3,1);
  --gutter:16px;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{margin:0;background:var(--ash);color:var(--ink);font:400 16px/1.5 var(--text);overflow-x:hidden}
img{display:block;max-width:100%}
a{color:inherit}
button,input{font:inherit;color:inherit}
:focus-visible{outline:2px solid var(--ember);outline-offset:2px}
.wrap{max-width:1240px;margin:0 auto;padding:0 var(--gutter)}
p{text-wrap:pretty}
h1,h2{text-wrap:balance}

/* header */
.top{position:absolute;inset:0 0 auto;z-index:5;color:#fff}
.top__in{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:12px var(--gutter);max-width:none}
.brand{display:flex;flex-direction:column;text-decoration:none;line-height:1}
.brand__name{font:700 26px/1 var(--display);letter-spacing:.01em}
.brand__sub{font-size:12px;color:rgba(255,255,255,.72);margin-top:3px}
.top__phone{font-weight:600;font-size:15px;text-decoration:none;padding:10px 0;white-space:nowrap}
.top__phone:hover{color:var(--ember)}

/* first screen: photo + picker */
.pick{background:var(--soot);color:#f3efe9;display:grid}
.pick__photo{margin:0;position:relative;height:50svh;min-height:330px;max-height:480px;overflow:hidden}
.pick__photo .readout{display:none}
.pick__photo img{width:100%;height:100%;object-fit:cover;object-position:62% 60%}
.pick__photo::before{content:"";position:absolute;inset:0 0 auto;height:110px;background:linear-gradient(rgba(20,17,14,.78),rgba(20,17,14,0));z-index:1}
.pick__photo::after{content:"";position:absolute;inset:auto 0 0;height:58%;background:linear-gradient(rgba(29,26,23,0),rgba(29,26,23,.9) 70%,var(--soot))}
.readout{position:absolute;left:var(--gutter);right:var(--gutter);bottom:14px;z-index:2;display:grid;grid-template-columns:auto 1fr;align-items:end;column-gap:14px}
.readout__label{grid-column:1/-1;font-size:14px;color:var(--smoke)}
.readout__num{font:700 76px/.86 var(--display);color:#fff;display:inline-flex;align-items:baseline;gap:6px}
.readout__num.flip{animation:flip .5s var(--ease)}
@keyframes flip{from{opacity:.25;transform:translateY(10px)}to{opacity:1;transform:none}}
.readout__unit{font-size:34px;color:var(--ember)}
.readout__calc{font-size:13px;line-height:1.35;color:#e6dfd6;padding-bottom:6px;max-width:30ch}

.pick__panel{position:relative;z-index:2;padding:0 var(--gutter) 30px;margin-top:-118px}
.pick__title{font:700 44px/.95 var(--display);margin:0 0 10px;letter-spacing:.005em}
.pick__lead{margin:0 0 20px;color:#d9d2c8;font-size:15px;max-width:46ch}
.pick__rule{margin:16px 0 0;font-size:13px;color:var(--smoke);max-width:52ch}

.steps{display:grid;gap:12px}
.step{border:1px solid var(--soot-line);border-radius:14px;padding:14px 14px 16px;margin:0;min-width:0;background:var(--soot-2)}
.step__head{display:flex;align-items:center;gap:10px;font-weight:600;font-size:16px;padding:0;margin-bottom:12px;float:left;width:100%}
.step__head + *{clear:both}
.step__n{display:inline-grid;place-items:center;width:26px;height:26px;border-radius:50%;border:1px solid var(--ember);color:var(--ember);font:700 17px/1 var(--display)}

.seg{display:grid;grid-template-columns:1fr 1fr;gap:6px;background:var(--soot);border-radius:10px;padding:4px;margin-bottom:12px}
.seg--3{grid-template-columns:repeat(3,1fr);margin-bottom:0}
.seg__opt{position:relative;cursor:pointer}
.seg__opt input,.choice__opt input{position:absolute;opacity:0;inset:0;margin:0;cursor:pointer}
.seg__opt span{display:flex;align-items:center;justify-content:center;min-height:44px;border-radius:7px;font-size:14px;font-weight:500;color:#d9d2c8;text-align:center;padding:4px 6px;transition:background-color .25s var(--ease),color .25s var(--ease)}
.seg__opt input:checked + span{background:#f3efe9;color:var(--ink)}
.seg__opt input:focus-visible + span{outline:2px solid var(--ember);outline-offset:1px}

.dims{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}
.dims--vol{grid-template-columns:minmax(0,220px)}
.dims[hidden]{display:none}
.num label{display:block;font-size:12px;color:var(--smoke);margin-bottom:5px}
.num__box{display:flex;align-items:stretch;border:1px solid var(--soot-line);border-radius:9px;background:var(--soot);overflow:hidden;height:46px}
.num__box:focus-within{border-color:var(--ember)}
.num__box input{width:100%;min-width:0;border:0;background:transparent;text-align:center;font:600 22px/1 var(--display);color:#fff;padding:0}
.num__box input:focus{outline:none}
.num__btn{flex:none;width:32px;border:0;background:transparent;color:var(--smoke);font-size:18px;cursor:pointer;touch-action:manipulation}
.num__btn:hover{color:#fff}

.choice{display:grid;gap:6px}
.choice__opt{position:relative;display:grid;grid-template-columns:1fr;align-items:center;gap:4px 12px;padding:11px 12px 11px 40px;border:1px solid var(--soot-line);border-radius:10px;cursor:pointer;transition:border-color .25s var(--ease),background-color .25s var(--ease)}
.choice__opt::before{content:"";position:absolute;left:13px;top:50%;width:16px;height:16px;margin-top:-8px;border-radius:50%;border:1.5px solid var(--smoke)}
.choice__opt::after{content:"";position:absolute;left:17px;top:50%;width:8px;height:8px;margin-top:-4px;border-radius:50%;background:var(--ember);transform:scale(0);transition:transform .25s var(--ease)}
.choice__opt:has(input:checked){border-color:#8a6a52;background:#322b24}
.choice__opt:has(input:checked)::after{transform:scale(1)}
.choice__opt:has(input:checked)::before{border-color:var(--ember)}
.choice__opt:has(input:focus-visible){outline:2px solid var(--ember);outline-offset:1px}
.choice__t{font-size:14px;font-weight:500;line-height:1.3}
.choice__d{font-size:12px;color:var(--smoke)}
.check{display:flex;gap:10px;align-items:flex-start;margin-top:12px;font-size:14px;cursor:pointer;line-height:1.35}
.check input{width:18px;height:18px;margin:1px 0 0;accent-color:var(--ember);flex:none}
.check em{display:block;font-style:normal;font-size:12px;color:var(--smoke)}

/* results */
.res{padding:40px 0 10px}
.res__head{margin-bottom:18px}
.h2{font:700 38px/1 var(--display);margin:0 0 8px;letter-spacing:.005em}
.res__note{margin:0;color:var(--muted);font-size:15px;max-width:60ch}
.res__note.warn{color:var(--ember-ink)}
.opts{display:grid;gap:12px}
.opt{position:relative;display:grid;grid-template-columns:100px 1fr;gap:12px;background:var(--paper);border:1px solid var(--line);border-radius:16px;padding:12px;cursor:pointer;opacity:0;transform:translateY(14px);transition:opacity .55s var(--ease),transform .55s var(--ease),border-color .25s var(--ease)}
.opt.in{opacity:1;transform:none}
.opt:hover{border-color:#b9b2a8}
.opt input{position:absolute;opacity:0;inset:0;margin:0;cursor:pointer}
.opt:has(input:checked){border-color:var(--ink);box-shadow:inset 0 0 0 1px var(--ink)}
.opt:has(input:focus-visible){outline:2px solid var(--ember);outline-offset:2px}
.opt__img{background:#fff;border-radius:10px;aspect-ratio:1;display:grid;place-items:center;overflow:hidden}
.opt__img img{width:100%;height:100%;object-fit:contain}
.opt__body{display:flex;flex-direction:column;min-width:0}
.opt__tag,.opt__brand,.opt__name{padding-right:30px}
.opt__brand{font-size:12px;color:var(--muted);margin:0 0 2px}
.opt__name{font-weight:600;font-size:16px;line-height:1.25;margin:0 0 6px}
.opt__range{font-size:13px;margin:0 0 4px}
.opt__why{font-size:13px;color:var(--muted);margin:0 0 10px;line-height:1.4}
.opt__foot{margin-top:auto;display:flex;flex-wrap:wrap;align-items:baseline;justify-content:space-between;gap:4px 12px}
.opt__price{font:700 30px/1 var(--display)}
.opt__link{position:relative;z-index:1;font-size:13px;color:var(--muted)}
.opt__link:hover{color:var(--ink)}
.opt__tick{position:absolute;top:12px;right:12px;width:24px;height:24px;border-radius:50%;border:1.5px solid var(--line);display:grid;place-items:center;background:#fff}
.opt__tick::after{content:"";width:10px;height:6px;border-left:2px solid #fff;border-bottom:2px solid #fff;transform:translateY(-1px) rotate(-45deg) scale(0);transition:transform .25s var(--ease)}
.opt:has(input:checked) .opt__tick{background:var(--ink);border-color:var(--ink)}
.opt:has(input:checked) .opt__tick::after{transform:translateY(-1px) rotate(-45deg) scale(1)}
.opt__tag{display:inline-block;font-size:12px;font-weight:500;color:var(--ember-ink);margin:0 0 4px}

/* kit */
.kit{padding:30px 0 56px}
.kit__grid{display:grid;gap:18px}
.sheet .h2{margin-bottom:14px}
.sheet__body{background:var(--paper);border:1px solid var(--line);border-radius:18px;padding:4px 16px}
#sheet{display:grid}
.grp{padding:16px 0;border-top:1px solid var(--line)}
.grp--stove{border-top:0}
.grp__head{display:flex;align-items:center;justify-content:space-between;gap:10px;margin:0 0 8px}
.grp__title{font:700 26px/1 var(--display);margin:0}
.grp__sub{font-size:13px;color:var(--muted);margin:0 0 10px}
.ln{display:grid;grid-template-columns:44px 1fr auto;gap:10px;align-items:center;padding:8px 0;border-top:1px solid #ece9e4}
.ln:first-of-type{border-top:0}
.ln__img{width:44px;height:44px;border-radius:8px;background:#fff;border:1px solid #eee9e3;object-fit:contain}
.ln__name{font-size:14px;line-height:1.3;min-width:0}
.ln__name a{text-decoration:none}
.ln__name a:hover{text-decoration:underline}
.ln__q{display:block;font-size:12px;color:var(--muted)}
.ln__p{font-weight:600;font-size:14px;white-space:nowrap}
.ln--main .ln__p{font-size:15px}
.ln--off{opacity:.45}
.note{font-size:13px;color:var(--muted);margin:8px 0 0;line-height:1.4}
.toggle{position:relative;display:inline-flex;align-items:center;gap:8px;font-size:13px;color:var(--muted);cursor:pointer;flex:none}
.toggle input{position:absolute;opacity:0;width:1px;height:1px}
.toggle__ui{width:40px;height:24px;border-radius:12px;background:#cfcac2;position:relative;transition:background-color .25s var(--ease)}
.toggle__ui::after{content:"";position:absolute;top:3px;left:3px;width:18px;height:18px;border-radius:50%;background:#fff;transition:transform .3s var(--ease)}
.toggle input:checked + .toggle__ui{background:var(--ink)}
.toggle input:checked + .toggle__ui::after{transform:translateX(16px)}
.toggle input:focus-visible + .toggle__ui{outline:2px solid var(--ember);outline-offset:2px}
.len{display:flex;align-items:center;gap:10px;margin:0 0 6px;font-size:13px;color:var(--muted);flex-wrap:wrap}
.len__box{display:inline-flex;align-items:center;border:1px solid var(--line);border-radius:9px;height:40px;background:#fff}
.len__box button{width:40px;height:100%;border:0;background:none;font-size:18px;cursor:pointer;color:var(--ink);touch-action:manipulation}
.len__box output{min-width:44px;text-align:center;font:600 20px/1 var(--display);color:var(--ink)}
.tanks{display:grid;gap:6px}
.tank{position:relative;display:grid;grid-template-columns:44px 1fr auto;gap:10px;align-items:center;padding:8px 10px;border:1px solid #e3dfd8;border-radius:10px;cursor:pointer;transition:border-color .25s var(--ease)}
.tank input{position:absolute;opacity:0;inset:0;margin:0;cursor:pointer}
.tank:has(input:checked){border-color:var(--ink);box-shadow:inset 0 0 0 1px var(--ink)}
.tank:has(input:focus-visible){outline:2px solid var(--ember);outline-offset:1px}
.tank--none{grid-template-columns:1fr;min-height:48px}
.tank a{position:relative;z-index:1}

.sum__box{background:var(--soot);color:#f3efe9;border-radius:18px;padding:20px 18px}
.sum__label{font-size:14px;font-weight:500;color:var(--smoke);margin:0}
.sum__total{font:700 58px/1 var(--display);margin:4px 0 12px}
.sum__total.flip{animation:flip .5s var(--ease)}
.sum__list{list-style:none;margin:0 0 16px;padding:0;font-size:13px;color:#d9d2c8;display:grid;gap:4px}
.sum__list li{display:flex;justify-content:space-between;gap:12px}
.sum__list b{font-weight:500;color:#f3efe9;white-space:nowrap}
.field{display:block;margin-bottom:12px}
.field span{display:block;font-size:13px;color:var(--smoke);margin-bottom:6px}
.field input{width:100%;height:48px;border-radius:10px;border:1px solid var(--soot-line);background:var(--soot-2);color:#fff;padding:0 14px;font-size:16px}
.field input::placeholder{color:#8f877c}
.field input:focus{outline:none;border-color:var(--ember)}
.wa{position:relative;display:flex;align-items:center;justify-content:center;gap:10px;min-height:54px;padding:10px 18px;border-radius:12px;background:var(--wa);color:#fff;font-weight:600;font-size:16px;text-decoration:none;overflow:hidden;isolation:isolate}
.wa::before{content:"";position:absolute;inset:0;background:var(--wa-hover);transform:scaleX(0);transform-origin:left;transition:transform .4s var(--ease);z-index:-1}
.wa:hover::before{transform:scaleX(1)}
.wa svg{width:22px;height:22px;flex:none}
.sum .wa{font-size:15px;gap:8px;padding:10px 12px}
.wa[aria-disabled="true"]{opacity:.5;pointer-events:none}
.sum__hint{font-size:13px;color:var(--smoke);margin:10px 0 0}
.msg{margin-top:14px;border-top:1px solid var(--soot-line);padding-top:10px}
.msg summary{cursor:pointer;font-size:14px;color:#e6dfd6;padding:6px 0}
.msg pre{white-space:pre-wrap;word-break:break-word;font:400 13px/1.5 var(--text);color:#d9d2c8;margin:8px 0 0;max-height:none}

.foot{background:var(--soot);color:var(--smoke);font-size:13px;padding:28px 0 104px}
.foot__in p{margin:0 0 8px;max-width:70ch}
.foot__brand{font:700 24px/1 var(--display);color:#f3efe9}
.foot a{color:#e6dfd6}

/* mobile sticky bar */
.bar{position:fixed;left:0;right:0;bottom:0;z-index:20;display:flex;align-items:center;gap:12px;padding:10px var(--gutter) calc(10px + env(safe-area-inset-bottom));background:var(--soot);color:#fff;border-top:1px solid var(--soot-line);transform:translateY(110%);transition:transform .5s var(--ease)}
.bar.on{transform:none}
.bar__sum,.bar__need{display:flex;flex-direction:column;line-height:1.1;flex:none}
.bar__need > span{font-size:12px;color:var(--smoke)}
.bar__need strong{font:700 28px/1 var(--display)}
.bar__go{flex:1;display:flex;align-items:center;justify-content:center;min-height:50px;border-radius:12px;background:#f3efe9;color:var(--ink);font-weight:600;font-size:15px;text-decoration:none}
.bar .bar__sum,.bar .wa--bar{display:none}
.bar.bar--sum .bar__sum,.bar.bar--sum .wa--bar{display:flex}
.bar.bar--sum .bar__need,.bar.bar--sum .bar__go{display:none}
.bar__sum span{font-size:12px;color:var(--smoke)}
.bar__sum strong{font:700 28px/1 var(--display)}
.wa--bar{flex:1;min-height:50px;font-size:15px}

@media (min-width:720px){
  :root{--gutter:28px}
  .pick__photo{height:52svh;max-height:560px}
  .readout__num{font-size:96px}
  .pick__title{font-size:56px}
  .opts{grid-template-columns:repeat(2,1fr)}
  .opt{grid-template-columns:1fr;padding:14px}

  .opt__img{aspect-ratio:4/3}
}
@media (min-width:1024px){
  :root{--gutter:40px}
  .top__in{padding:18px var(--gutter)}
  .brand__name{font-size:30px}
  .top__phone{font-size:17px}
  .pick{grid-template-columns:minmax(500px,560px) 1fr;min-height:100svh}
  .pick__panel{grid-column:1;grid-row:1;margin-top:0;padding:88px 40px 28px var(--gutter);align-self:center}
  .pick__photo{grid-column:2;grid-row:1;height:100svh;max-height:none;min-height:0;position:sticky;top:0;align-self:start}
  .pick__photo .readout{display:grid}
  .pick__photo img{position:absolute;inset:0;object-position:56% 62%}
  .pick__photo::after{height:48%;background:linear-gradient(rgba(29,26,23,0),rgba(29,26,23,.86))}
  .pick__photo::before{height:150px}
  .readout{left:40px;bottom:36px;right:40px;column-gap:22px}
  .readout__num{font-size:132px}
  .readout__unit{font-size:52px}
  .readout__calc{font-size:15px;max-width:36ch;padding-bottom:12px}
  .pick__title{font-size:58px}
  .pick__lead{font-size:15px;margin-bottom:16px}
  .res{padding:72px 0 16px}
  .h2{font-size:48px}
  .opts{grid-template-columns:repeat(3,1fr);gap:16px}
  .sheet__body{padding:6px 28px}
  #sheet{grid-template-columns:1fr 1fr;grid-template-rows:auto 1fr;grid-template-areas:"ch stove" "ch tank";column-gap:28px}
  .grp--stove{grid-area:stove}
  .grp--tank{grid-area:tank}
  .grp--ch{grid-area:ch;border-top:0}
  .seg__opt span{min-height:38px}
  .choice__opt{grid-template-columns:1fr auto;padding-top:9px;padding-bottom:9px}
  .choice__d{text-align:right;white-space:nowrap}
  .steps{gap:10px}
  .step__head{width:auto;margin-bottom:10px}
  .seg--mode{float:right;width:236px;margin:-6px 0 8px;padding:3px}
  .seg--mode .seg__opt span{min-height:34px;font-size:13px}
  .dims{clear:both}
  .step{padding:12px 14px 14px}
  .kit{padding:40px 0 88px}
  .kit__grid{grid-template-columns:1fr 380px;gap:28px;align-items:start}
  .sum{position:sticky;top:24px}
  .sum__box{padding:26px 24px}
  .bar{display:none}
  .foot{padding-bottom:36px}
}
@media (min-width:1024px) and (max-height:920px){
  .pick__panel{padding-top:76px;padding-bottom:16px}
  .pick__title{font-size:46px;margin-bottom:6px}
  .pick__lead{font-size:14px}
  .step__head{margin-bottom:8px}
  .choice{gap:4px}
  .num__box{height:42px}
  .check{margin-top:8px}
  .pick__lead{margin-bottom:14px}
  .steps{gap:10px}
  .step__head{width:auto;margin-bottom:10px}
  .seg--mode{float:right;width:236px;margin:-6px 0 8px;padding:3px}
  .seg--mode .seg__opt span{min-height:34px;font-size:13px}
  .dims{clear:both}
  .step{padding:12px 14px 14px}
  .choice__opt{padding-top:9px;padding-bottom:9px}
  .pick__rule{display:none}
}
@media (min-width:1024px) and (max-height:790px){
  .pick__panel{padding-top:70px}
  .pick__lead{display:none}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
}