/* Backtrack public site. Always light (product decision); system faces only, no third-party fonts.
   Home: a scroll story (html.motion + motion.js). Without JS or with reduced motion the same markup is a plain page. */
:root{
  color-scheme:light;
  --bg:#fbfbfd;--surface:#ffffff;--soft:#f2f4f3;--ink:#1d1d1f;--muted:#6e6e73;--line:#d9dcdb;
  --brand:#005d56;--brand-soft:#e3efec;--forest:#0b3a34;--night:#07110f;--sun:#f3b23a;
  --font:-apple-system,BlinkMacSystemFont,"SF Pro Display","SF Pro Text","Helvetica Neue","Segoe UI",system-ui,sans-serif;
  --gutter:clamp(20px,5vw,56px);--max:1120px;--bar:52px;
  --side:max(var(--gutter),calc((100% - var(--max))/2));
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:var(--bar)}
html,body{overflow-x:clip}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.5 var(--font);letter-spacing:-.011em;-webkit-font-smoothing:antialiased}
img{max-width:100%;height:auto;display:block}
a{color:var(--brand);text-underline-offset:3px}
a:focus-visible,summary:focus-visible,.button:focus-visible{outline:3px solid var(--sun);outline-offset:3px;border-radius:8px}
h1,h2,h3{line-height:1.08;text-wrap:balance;margin:0;letter-spacing:-.03em}
h1{font-size:clamp(2.4rem,5.6vw,4.6rem);font-weight:700}
h2{font-size:clamp(1.9rem,4vw,3rem);font-weight:700}
h3{font-size:1.15rem;font-weight:600;letter-spacing:-.015em}
p{margin:0}
.skip{position:absolute;left:-999px}.skip:focus{left:16px;top:12px;background:var(--surface);padding:8px 12px;z-index:99}
.button{display:inline-flex;align-items:center;min-height:46px;padding:0 24px;border-radius:999px;background:var(--brand);color:#fff;font-weight:600;text-decoration:none}
.button:hover{background:var(--forest)}

/* Header: thin translucent bar, as on product pages */
.top{position:sticky;top:0;z-index:50;height:var(--bar);display:flex;align-items:center;gap:28px;padding-inline:var(--side);
  background:rgba(251,251,253,.8);-webkit-backdrop-filter:saturate(180%) blur(20px);backdrop-filter:saturate(180%) blur(20px);border-bottom:1px solid rgba(0,0,0,.07)}
.brand{display:flex;align-items:center;gap:9px;color:var(--ink);text-decoration:none;font-weight:600;font-size:1.02rem;letter-spacing:-.02em}
.brand img{width:28px;height:28px;border-radius:7px}
.top nav{display:flex;gap:24px;margin-left:auto}
.top nav a,.langs a{color:var(--ink);text-decoration:none;font-size:.86rem;opacity:.85}
.top nav a:hover,.langs a:hover{opacity:1}
.langs{display:flex;gap:2px;margin:0}
.langs a{padding:4px 8px;border-radius:7px;font-size:.78rem;font-weight:600}.langs a[aria-current]{background:var(--ink);color:var(--bg);opacity:1}
.top{transition:background-color .3s,border-color .3s}
.top.dark{background:rgba(10,16,14,.72);border-color:rgba(255,255,255,.08)}
.top.dark .brand,.top.dark nav a,.top.dark .langs a{color:#f5f5f7}.top.dark .langs a[aria-current]{background:#f5f5f7;color:#101614}

/* ---------- Scroll story, plain layout (no JS / reduced motion) ---------- */
.scene .stage{max-width:var(--max);margin:0 auto;padding:clamp(56px,9vw,112px) var(--gutter);display:grid;grid-template-columns:minmax(0,1fr) auto;gap:clamp(32px,6vw,88px);align-items:center}
.copy{display:grid;gap:56px}
.beat h1,.beat h2{max-width:13em}
.beat h2{font-size:clamp(2rem,4.4vw,3.6rem)}
.beat p{margin-top:20px;font-size:clamp(1.06rem,1.45vw,1.3rem);line-height:1.45;color:var(--muted);max-width:29em}
.beat .status{margin-top:28px;font-size:.95rem;color:inherit;opacity:.8}
.roll,.shade,.chips,.polaroids{display:none}
.s-roll .stage{grid-template-columns:1fr}
.sunset{width:100%;max-height:72vh;object-fit:cover;border-radius:28px}
.slot{position:relative;justify-self:center}
.phone{--h:min(680px,80vh);height:var(--h);aspect-ratio:.4754;padding:3%;border-radius:15%/7%;background:#1d1d1f;
  box-shadow:0 0 0 1px rgba(0,0,0,.2),0 50px 90px -40px rgba(0,30,25,.45)}
.screen{position:relative;width:100%;height:100%;border-radius:12.5%/5.8%;overflow:hidden;background:#fff;isolation:isolate}
.screen>*{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.card{--h:min(760px,82vh);position:relative;margin:0;height:var(--h);aspect-ratio:600/1066;border-radius:6%/3.4%;overflow:hidden;background:#dfe9e6;
  box-shadow:0 60px 120px -50px rgba(0,0,0,.8),0 0 0 1px rgba(255,255,255,.08)}
.card>*{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
figure{margin:0}
.s-route{background:var(--night);color:#f5f5f7}
.s-route .beat p{color:#a3aaa8}
.s-end .stage{grid-template-columns:1fr;justify-items:center;text-align:center}
.lockup{display:grid;justify-items:center;gap:0}
.mark{width:112px;height:112px;filter:drop-shadow(0 18px 30px rgba(0,60,50,.3))}
.word{margin-top:20px;font-size:clamp(2.4rem,4.6vw,3.4rem);font-weight:700;letter-spacing:-.04em;line-height:1}
.slogan{margin-top:8px;font-size:1.2rem;color:var(--muted)}
.lockup h2{margin-top:48px;font-size:clamp(1.6rem,3vw,2.2rem)}
.end-text{margin-top:10px;color:var(--muted);font-size:1.1rem}
.end-actions{margin-top:24px;display:flex;flex-wrap:wrap;align-items:center;justify-content:center;gap:12px 18px}
.email{color:var(--muted);font-size:.95rem;user-select:all}
.note{margin-top:36px;max-width:36em;font-size:.82rem;color:var(--muted)}

/* ---------- Scroll story, motion layout ---------- */
.motion .scene{position:relative;height:calc(var(--len)*1vh)}
.motion .scene .stage{position:sticky;top:0;height:100vh;max-width:none;margin:0;padding:var(--bar) var(--side) 0;overflow:hidden}
.motion .copy{display:grid;gap:0}
.motion .beat{grid-area:1/1;align-self:center}
.motion .beat:not([data-in="0"]){opacity:0}
.motion .phone{--h:min(calc(100vh - var(--bar) - 88px),800px)}
.motion .card{--h:min(calc(100vh - var(--bar) - 72px),860px)}
.motion .screen>.seq,.motion .card>.seq{opacity:0}
.motion .chips{display:block;list-style:none;margin:0;padding:0}
.chips li{position:absolute;opacity:0;white-space:nowrap;padding:.62em 1.1em;border-radius:999px;background:rgba(255,255,255,.92);color:var(--ink);
  font-size:clamp(15px,1.25vw,19px);font-weight:600;letter-spacing:-.01em;box-shadow:0 18px 40px -16px rgba(0,40,34,.35),0 0 0 1px rgba(0,0,0,.05);
  -webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px)}
.s-app .chips li:nth-child(1){left:-30%;top:24%}
.s-app .chips li:nth-child(2){right:-26%;top:47%}
.s-app .chips li:nth-child(3){left:-24%;top:70%}
.s-share .chips li:nth-child(1){left:-22%;top:20%;background:var(--ink);color:#fff}
.s-share .chips li:nth-child(2){right:-18%;top:31%}
.s-share .chips li:nth-child(3){left:-16%;top:50%}
.s-share .chips li:nth-child(4){right:-32%;top:72%}
.s-share .chips li:nth-child(4)::before{content:"✓ ";color:var(--brand)}
.tap{position:absolute;width:18%;aspect-ratio:1;left:73.1%;top:34.4%;margin:-9% 0 0 -9%;border-radius:50%;background:rgba(0,93,86,.28);opacity:0;inset:auto;height:auto}
.push{box-shadow:-20px 0 40px rgba(0,0,0,.12)}
.scroller{overflow:hidden}
.scroller img{position:absolute;left:0;top:0;width:100%;height:auto}

/* Opening: one sunset, then the camera roll it is lost in */
.motion .s-roll .stage{padding:0;display:block;background:#000;color:#fff}
.motion .roll{display:block;position:absolute;left:0;top:0;transform-origin:0 0}
.roll .tile{position:absolute;overflow:hidden;background:#222}
.roll .tile img{width:100%;height:100%;object-fit:cover}
.roll .tile i{position:absolute;inset:0;background:#000;opacity:0}
.roll .tile.hit{box-shadow:0 0 0 3px #fff,0 14px 30px rgba(0,0,0,.5)}
.motion .sunset{position:absolute;left:0;top:0;width:100%;height:100%;max-height:none;border-radius:0}
.motion .shade{display:block;position:absolute;inset:0;background:linear-gradient(to top,rgba(0,0,0,.78),rgba(0,0,0,.25) 45%,rgba(0,0,0,0) 70%);pointer-events:none}
.motion .s-roll .copy{position:absolute;left:var(--side);right:var(--side);bottom:clamp(40px,9vh,104px)}
.motion .s-roll .beat{align-self:end}
.motion .s-roll .beat p{color:rgba(255,255,255,.84)}
.motion .s-roll h1{font-size:clamp(2.5rem,6vw,5.2rem);max-width:12em}
.s-roll .beat h2{font-size:clamp(2rem,4.4vw,3.6rem)}

/* Closing: polaroids gather around the brand */
.motion .s-end .stage{display:grid;place-items:center;padding:var(--bar) var(--gutter) 0}
.motion .polaroids{display:block;position:absolute;left:50%;top:calc(50% + var(--bar)/2);width:0;height:0}
.polaroid{position:absolute;width:clamp(96px,12vw,180px);margin:0;padding:6% 6% 0;background:#fff;border-radius:4px;box-shadow:0 24px 50px -18px rgba(0,30,25,.45),0 0 0 1px rgba(0,0,0,.04);transform-origin:50% 50%}
.polaroid img{width:100%;aspect-ratio:1;object-fit:cover}
.polaroid span{display:block;padding:.55em 0 .7em;font-size:clamp(10px,.95vw,14px);font-weight:600;color:#3a4442;text-align:center;letter-spacing:0}
.motion .lockup{position:relative;z-index:2}
.motion .lockup>*{will-change:opacity,transform}

/* ---------- Content after the story ---------- */
.reveal{opacity:0;transform:translate3d(0,48px,0);transition:opacity 1s cubic-bezier(.2,.7,.2,1),transform 1s cubic-bezier(.2,.7,.2,1)}
.reveal.in{opacity:1;transform:none}
.sections{max-width:var(--max);margin:0 auto;padding:clamp(88px,12vw,160px) var(--gutter);display:grid;gap:clamp(88px,11vw,150px)}
.world{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:clamp(28px,6vw,72px);align-items:center;background:var(--soft);border-radius:32px;padding:clamp(28px,5vw,64px)}
.world-copy{display:grid;gap:18px;max-width:30em}.world-copy p{color:var(--muted);font-size:clamp(1.05rem,1.3vw,1.2rem)}
.device{width:min(280px,70vw);justify-self:center}
.device img{width:100%;border-radius:40px;border:9px solid #1d1d1f;background:#1d1d1f;box-shadow:0 40px 70px -30px rgba(0,30,25,.4)}
.features,.compare,.guides,.faq,.glance{display:grid;gap:36px}
.features ul{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:40px 48px}
.features li{display:grid;gap:8px;align-content:start}
.features p{color:var(--muted);font-size:.98rem}
.glance dl{margin:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0 48px;border-top:1px solid var(--line)}
.glance dl div{display:grid;grid-template-columns:9em minmax(0,1fr);gap:16px;padding-block:16px;border-bottom:1px solid var(--line)}
.glance dt{font-weight:600}
.glance dd{margin:0;color:var(--muted);font-size:.98rem}
.compare>p{color:var(--muted);max-width:40em;margin-top:-20px;font-size:1.1rem}
.table{overflow-x:auto;border-radius:20px;background:var(--surface);box-shadow:0 0 0 1px var(--line)}
table{width:100%;border-collapse:collapse;min-width:560px}
th,td{text-align:left;padding:16px 22px;border-bottom:1px solid var(--line);vertical-align:top}
tbody tr:last-child th,tbody tr:last-child td{border-bottom:0}
thead th{font-weight:600;font-size:.92rem;color:var(--muted)}
thead th:nth-child(2),tbody td:nth-child(2){background:var(--brand-soft)}
thead th:nth-child(2){color:var(--brand)}
tbody th{font-weight:600}
.guides ul{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
.guides a{display:grid;gap:10px;height:100%;padding:28px;border-radius:22px;background:var(--surface);box-shadow:0 0 0 1px var(--line);color:var(--ink);text-decoration:none;transition:box-shadow .2s}
.guides a:hover{box-shadow:0 0 0 2px var(--brand)}
.guides a h3{font-size:1.25rem}.guides a p{color:var(--muted);font-size:.95rem}
.faq>div{display:grid;border-top:1px solid var(--line)}
details{border-bottom:1px solid var(--line)}
summary{cursor:pointer;list-style:none;display:flex;justify-content:space-between;gap:20px;padding-block:20px;font-weight:600;font-size:1.08rem;line-height:1.35}
summary::-webkit-details-marker{display:none}
summary::after{content:"+";font-size:1.5rem;line-height:1;font-weight:400;color:var(--brand)}
details[open] summary::after{content:"–"}
details p{padding-bottom:22px;color:var(--muted);max-width:44em}
.updated{font-size:.85rem;color:var(--muted)}

/* Guide and legal pages */
.guide,.legal{max-width:760px;margin:0 auto;padding:clamp(32px,6vw,64px) var(--gutter) 96px;display:grid;gap:28px}
.guide article{display:grid;gap:24px}
.guide h1{font-size:clamp(2rem,4.6vw,3.2rem)}
.crumbs{font-size:.88rem;color:var(--muted)}.crumbs a{color:var(--muted)}
.answer{background:var(--surface);box-shadow:0 0 0 1px var(--line);border-left:5px solid var(--brand);border-radius:18px;padding:22px 24px}
.answer p{font-size:1.1rem}
.route-steps{list-style:none;margin:0;padding:0;display:grid;gap:26px;counter-reset:stop;position:relative}
.route-steps::before{content:"";position:absolute;left:22px;top:22px;bottom:22px;border-left:3px dashed var(--brand);opacity:.45}
.route-steps li{counter-increment:stop;position:relative;display:grid;gap:8px;padding:0 0 0 70px;min-height:46px}
.route-steps li::before{content:counter(stop);position:absolute;top:0;left:0;width:46px;height:46px;border-radius:50%;background:var(--brand);color:#fff;
  display:grid;place-items:center;font-weight:700;font-size:1.05rem;box-shadow:0 0 0 5px var(--bg)}
.route-steps p{color:var(--muted)}
.tips{margin:0;display:grid}
.tips div{display:grid;grid-template-columns:12em minmax(0,1fr);gap:16px;padding-block:14px;border-bottom:1px solid var(--line)}
.tips dt{font-weight:600}.tips dd{margin:0;color:var(--muted)}
.next{display:flex;flex-wrap:wrap;align-items:center;gap:14px 24px;padding-top:28px;border-top:1px solid var(--line)}
.next a:not(.button){flex-basis:100%}
.legal section{display:grid;gap:10px}.legal section p,.legal details p{color:var(--muted)}

/* Footer */
.foot{display:grid;grid-template-columns:auto minmax(0,1fr);gap:20px 48px;padding:32px var(--side) 48px;border-top:1px solid var(--line);font-size:.86rem;color:var(--muted);background:var(--soft)}
.foot-brand{display:grid;gap:2px}.foot-brand strong{color:var(--ink)}
.foot-links{display:flex;flex-wrap:wrap;gap:10px 22px;justify-content:flex-end}
.foot-links a{color:var(--muted)}
.foot-meta{grid-column:1/-1}

@media (max-width:900px){
  .features ul{grid-template-columns:repeat(2,minmax(0,1fr))}
  .glance dl{grid-template-columns:1fr}
  .world{grid-template-columns:1fr}
}
/* Phones: copy on top, the screen below it, sized to what is left (motion.js measures --copy) */
@media (max-width:760px){
  .scene .stage{grid-template-columns:1fr;justify-items:center}
  .copy{justify-self:stretch}
  .motion .scene .stage{grid-template-rows:auto minmax(0,1fr);align-content:start;gap:18px;padding-top:calc(var(--bar) + 18px)}
  .motion .beat{align-self:start}
  .motion .phone{--h:min(calc(100svh - var(--bar) - var(--copy,40svh) - 54px),640px)}
  .motion .card{--h:min(calc(100svh - var(--bar) - var(--copy,34svh) - 48px),700px)}
  .beat h2{font-size:clamp(1.65rem,7.4vw,2.2rem)}
  .beat p{margin-top:12px;font-size:1rem;line-height:1.42}
  .motion .s-roll h1{font-size:clamp(2.2rem,9.5vw,3rem)}
  .motion .s-roll .copy{bottom:36px}
  .chips li{font-size:14px}
  .polaroid{width:84px}.lockup h2{margin-top:32px}.note{margin-top:24px}
  .s-app .chips li:nth-child(1){left:-18%}.s-app .chips li:nth-child(2){right:-16%}.s-app .chips li:nth-child(3){left:-14%}
  .s-share .chips li:nth-child(1){left:-14%}.s-share .chips li:nth-child(2){right:-12%}.s-share .chips li:nth-child(3){left:-12%}.s-share .chips li:nth-child(4){right:-18%}
  .top{gap:14px}.top nav{display:none}.langs{margin-left:auto}
}
@media (max-width:620px){
  body{font-size:16px}
  .features ul,.guides ul{grid-template-columns:1fr}
  .glance dl div,.tips div{grid-template-columns:1fr;gap:4px}
  .foot{grid-template-columns:1fr}.foot-links{justify-content:flex-start}
}
@media (max-width:760px) and (max-height:700px){
  .motion .scene .beat p{font-size:.94rem}
}