/* Solved Math website: one stylesheet for the landing page and the help/legal pages (docs/web/README.md).
   Colours are the app's (docs/DESIGN.md §2): quiet slate surfaces, white cards, one Ink accent. */
@font-face{font-family:"Solved Sans";src:url("/assets/fonts/ui-sans.woff2") format("woff2");font-weight:400 700;font-style:normal;font-display:swap}

:root{
  color-scheme:light dark;
  --bg:#EFEFED;--surface:#FFFFFF;--surface-2:#E6E7E4;--surface-3:#E0E1DD;--surface-4:#D9DAD5;
  --fg:#1F1F1F;--muted:#4A5558;--line:#C8CBC6;
  --ink:#2456C9;--on-ink:#FFFFFF;--ink-soft:#DCE5FB;--on-ink-soft:#0B2A6B;
  --primary:#586063;--on-primary:#FFFFFF;--primary-soft:#D9E0DA;
  --success:#2E7D32;--danger:#BA1A1A;--on-danger:#FFFFFF;
  --warn-bg:#FFF1CC;--warn-fg:#5A4300;--ok-bg:#DDF1DE;--ok-fg:#14532D;--err-bg:#FFDAD6;--err-fg:#690005;
  --shadow:0 1px 2px rgba(20,24,28,.06),0 12px 32px -12px rgba(20,24,28,.18);
  --phone-shadow:0 2px 4px rgba(20,24,28,.08),0 30px 60px -24px rgba(20,32,64,.35);
  --radius:24px;--wrap:1160px;
  --font:"Solved Sans",system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
}
@media (prefers-color-scheme:dark){:root{
  --bg:#1B1C1B;--surface:#2A2B2A;--surface-2:#232423;--surface-3:#343534;--surface-4:#3E3F3D;
  --fg:#E3E3E1;--muted:#C3C9C5;--line:#444846;
  --ink:#AFC6FF;--on-ink:#0B2A6B;--ink-soft:#24396B;--on-ink-soft:#DCE5FB;
  --primary:#B9C6CA;--on-primary:#233034;--primary-soft:#3F4B4F;
  --success:#A8DAA0;--danger:#FFB4AB;--on-danger:#690005;
  --warn-bg:#3A3010;--warn-fg:#FFE7A3;--ok-bg:#1F3A22;--ok-fg:#B9F0C9;--err-bg:#3D1414;--err-fg:#FFD2D2;
  --shadow:0 1px 2px rgba(0,0,0,.3),0 12px 32px -12px rgba(0,0,0,.5);
  --phone-shadow:0 2px 4px rgba(0,0,0,.3),0 30px 60px -20px rgba(0,0,0,.7);
}}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:80px}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important;animation:none!important}}
body{margin:0;background:var(--bg);color:var(--fg);font:400 17px/1.6 var(--font);-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;overflow-x:hidden}
img{max-width:100%;height:auto}
a{color:var(--ink);text-underline-offset:.18em;text-decoration-thickness:1px}
a:hover{text-decoration-thickness:2px}
:focus-visible{outline:3px solid var(--ink);outline-offset:3px;border-radius:6px}
h1,h2,h3{font-weight:500;letter-spacing:-.015em;line-height:1.2;margin:0 0 .5em;text-wrap:balance}
p{margin:0 0 1em}
.wrap{max-width:var(--wrap);margin:0 auto;padding:0 24px}
.muted{color:var(--muted)}
.visually-hidden{position:absolute!important;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.skip{position:absolute;left:16px;top:-60px;z-index:100;background:var(--ink);color:var(--on-ink);padding:10px 16px;border-radius:999px;text-decoration:none;font-weight:500}
.skip:focus{top:12px}

/* Header */
.site-header{position:sticky;top:0;z-index:50;background:color-mix(in srgb,var(--bg) 82%,transparent);-webkit-backdrop-filter:saturate(1.4) blur(14px);backdrop-filter:saturate(1.4) blur(14px);border-bottom:1px solid color-mix(in srgb,var(--line) 55%,transparent)}
.bar{display:flex;align-items:center;gap:24px;height:68px}
.brand{display:inline-flex;align-items:center;gap:10px;color:var(--fg);text-decoration:none;font-weight:500;font-size:1.12rem;letter-spacing:-.01em;margin-right:auto}
.brand img{width:34px;height:34px;border-radius:9px;display:block}
.nav{display:flex;gap:4px}
.nav a{color:var(--muted);text-decoration:none;font-weight:500;font-size:.95rem;padding:8px 12px;border-radius:999px}
.nav a:hover{color:var(--fg);background:var(--surface-3)}
@media (max-width:820px){.nav{display:none}}

/* Buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:48px;padding:0 22px;border-radius:999px;font:500 1rem/1 var(--font);text-decoration:none;border:0;cursor:pointer;transition:transform .15s ease,background-color .15s ease}
.btn:hover{text-decoration:none;transform:translateY(-1px)}
.btn-ink{background:var(--ink);color:var(--on-ink)}
.btn-tonal{background:var(--surface-3);color:var(--fg)}
.btn-small{min-height:40px;padding:0 18px;font-size:.95rem}
.play-badge{display:inline-block;line-height:0;border-radius:12px}
.play-badge img{display:block;height:88px;width:auto;margin:-13px -14px}
.cta-row{display:flex;flex-wrap:wrap;align-items:center;gap:20px 28px}

/* Hero */
.hero{position:relative;padding:72px 0 40px;overflow:hidden}
.hero::before{content:"";position:absolute;inset:0;background:radial-gradient(560px 460px at 72% 42%,color-mix(in srgb,var(--ink) 15%,transparent),transparent 72%);pointer-events:none}
.hero-grid{position:relative;display:grid;grid-template-columns:minmax(0,1.05fr) minmax(0,.95fr);gap:48px;align-items:center}
.eyebrow{display:inline-flex;align-items:center;gap:8px;background:var(--ink-soft);color:var(--on-ink-soft);font-weight:500;font-size:.88rem;padding:6px 14px 6px 10px;border-radius:999px;margin-bottom:24px}
.eyebrow svg{width:18px;height:18px}
.hero h1{font-size:clamp(2.4rem,4.7vw,4.1rem);line-height:1.04;letter-spacing:-.035em;margin-bottom:24px}
.hero h1 em{font-style:normal;color:var(--ink)}
.lede{font-size:clamp(1.08rem,1.5vw,1.25rem);color:var(--muted);max-width:34em;margin-bottom:32px}
.hero-meta{display:flex;flex-wrap:wrap;gap:8px 20px;margin:28px 0 0;padding:0;list-style:none;color:var(--muted);font-size:.93rem}
.hero-meta li{display:inline-flex;align-items:center;gap:8px}
.hero-meta svg{width:18px;height:18px;color:var(--ink);flex:none}
.hero-art{position:relative;height:620px;display:flex;justify-content:center}
.hero-art .phone{position:absolute;width:280px}
.hero-art .phone:nth-child(1){z-index:2;left:50%;transform:translateX(-84%) rotate(-2deg);top:0}
.hero-art .phone:nth-child(2){z-index:1;left:50%;transform:translateX(-4%) rotate(3deg);top:64px}
.hero-art .phone:only-child{transform:translateX(-50%)}
.chip{position:absolute;z-index:3;display:inline-flex;align-items:center;gap:8px;background:var(--surface);color:var(--fg);box-shadow:var(--shadow);border-radius:16px;padding:10px 14px;font-weight:500;font-size:.92rem;white-space:nowrap}
.chip svg{width:20px;height:20px;color:var(--ink)}
.chip-a{left:0;top:330px}
.chip-b{right:0;bottom:40px}
@media (max-width:960px){
  .hero{padding-top:48px}
  .hero-grid{grid-template-columns:1fr;gap:24px}
  .hero-art{height:520px;margin-top:8px}
  .hero-art .phone{width:236px}
  .chip-a{left:0;top:250px}.chip-b{right:0;bottom:20px}
}
@media (max-width:480px){
  .hero-art{height:440px}
  .hero-art .phone{width:196px}
  .hero-art .phone:nth-child(1){transform:translateX(-86%) rotate(-2deg)}
  .hero-art .phone:nth-child(2){transform:translateX(-10%) rotate(3deg);top:44px}
  .chip{font-size:.82rem;padding:8px 12px}
  .chip-a{top:200px}.chip-b{bottom:12px}
}

/* Phone frame around a 1080×2400 screenshot */
.phone{margin:0;aspect-ratio:1080/2400;background:#0E0F10;border-radius:40px;padding:9px;box-shadow:var(--phone-shadow);position:relative}
.phone img{display:block;width:100%;height:100%;object-fit:cover;object-position:top;border-radius:31px;background:#EFEFED}

/* Sections */
main:not(.doc)>section{padding:88px 0}
.section-head{max-width:720px;margin:0 0 48px}
.section-head.center{margin-inline:auto;text-align:center}
.kicker{display:block;color:var(--ink);font-weight:500;font-size:.92rem;letter-spacing:.06em;text-transform:uppercase;margin-bottom:12px}
.section-head h2{font-size:clamp(1.9rem,3.6vw,2.9rem);letter-spacing:-.03em;margin-bottom:16px}
.section-head p{color:var(--muted);font-size:1.1rem;margin:0}
.band{background:var(--surface-2)}
@media (max-width:640px){main:not(.doc)>section{padding:64px 0}.wrap{padding:0 16px}}

/* Features */
.features{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px}
.feature{background:var(--surface);border-radius:var(--radius);padding:28px 24px 26px}
.feature .icon{display:grid;place-items:center;width:48px;height:48px;border-radius:14px;background:var(--surface-3);color:var(--fg);margin-bottom:20px}
.feature .icon svg{width:24px;height:24px}
.feature.accent .icon{background:var(--ink-soft);color:var(--on-ink-soft)}
.feature h3{font-size:1.15rem;margin-bottom:8px}
.feature p{color:var(--muted);font-size:.98rem;margin:0}
@media (max-width:1040px){.features{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:560px){.features{grid-template-columns:1fr}}

/* Screens gallery */
.gallery{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:40px 28px;margin:0;padding:0;list-style:none}
.gallery li{margin:0}
.gallery figure{margin:0}
.gallery .phone{width:100%;max-width:232px;margin:0 auto}
.gallery figcaption{text-align:center;margin-top:18px}
.gallery figcaption strong{display:block;font-weight:500;font-size:1.02rem}
.gallery figcaption span{color:var(--muted);font-size:.93rem}
@media (max-width:960px){
  .gallery{display:flex;overflow-x:auto;scroll-snap-type:x mandatory;gap:20px;padding:8px 24px 24px;margin:0 -24px;scrollbar-width:thin;-webkit-overflow-scrolling:touch}
  .gallery li{flex:0 0 220px;scroll-snap-align:center}
}
@media (max-width:640px){.gallery{padding:8px 16px 24px;margin:0 -16px}.gallery li{flex-basis:200px}}

/* How it works */
.steps{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;counter-reset:step;margin:0;padding:0;list-style:none}
.steps li{background:var(--surface);border-radius:var(--radius);padding:28px}
.steps .num{display:grid;place-items:center;width:40px;height:40px;border-radius:50%;background:var(--ink);color:var(--on-ink);font-weight:500;margin-bottom:18px}
.steps h3{font-size:1.2rem;margin-bottom:8px}
.steps p{color:var(--muted);margin:0}
@media (max-width:860px){.steps{grid-template-columns:1fr}}

/* Plans */
.plans{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;align-items:stretch}
.plan{background:var(--surface);border-radius:var(--radius);padding:32px 28px;display:flex;flex-direction:column}
.plan h3{font-size:1.4rem;margin-bottom:4px}
.plan .tag{color:var(--muted);margin-bottom:20px}
.plan ul{list-style:none;margin:0;padding:0;display:grid;gap:12px}
.plan li{display:flex;gap:12px;align-items:flex-start}
.plan li svg{flex:none;width:20px;height:20px;margin-top:3px;color:var(--ink)}
.plan.plus{background:var(--ink);color:var(--on-ink)}
.plan.plus .tag{color:color-mix(in srgb,var(--on-ink) 78%,transparent)}
.plan.plus li svg{color:var(--on-ink)}
.plan .badge{align-self:flex-start;background:color-mix(in srgb,var(--on-ink) 16%,transparent);color:var(--on-ink);font-size:.8rem;font-weight:500;letter-spacing:.04em;text-transform:uppercase;padding:4px 10px;border-radius:999px;margin-bottom:16px}
.plans-note{color:var(--muted);text-align:center;margin:28px auto 0;max-width:640px;font-size:.95rem}
@media (max-width:900px){.plans{grid-template-columns:1fr}}

/* FAQ */
.faq{max-width:820px;margin:0 auto;display:grid;gap:12px}
.faq details{background:var(--surface);border-radius:20px;padding:0 24px}
.faq summary{list-style:none;cursor:pointer;display:flex;justify-content:space-between;align-items:center;gap:16px;padding:22px 0;font-weight:500;font-size:1.08rem}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"";flex:none;width:12px;height:12px;border-right:2px solid var(--muted);border-bottom:2px solid var(--muted);transform:rotate(45deg) translate(-3px,-3px);transition:transform .2s ease}
.faq details[open] summary::after{transform:rotate(225deg) translate(-3px,-3px)}
.faq details p{color:var(--muted);margin:0 0 22px}

/* Final call to action */
.cta-band{padding:0 0 96px}
.cta-card{background:var(--ink);color:var(--on-ink);border-radius:32px;padding:56px 48px;display:flex;align-items:center;justify-content:space-between;gap:32px;flex-wrap:wrap;position:relative;overflow:hidden}
.cta-card::after{content:"";position:absolute;right:-80px;top:-120px;width:420px;height:420px;border-radius:50%;background:color-mix(in srgb,var(--on-ink) 8%,transparent)}
.cta-card h2{font-size:clamp(1.7rem,3vw,2.4rem);letter-spacing:-.025em;margin:0 0 8px;position:relative}
.cta-card p{margin:0;color:color-mix(in srgb,var(--on-ink) 80%,transparent);position:relative}
.cta-card .play-badge{position:relative;z-index:1}
@media (max-width:640px){.cta-card{padding:40px 24px;border-radius:24px}}

/* Footer */
.site-footer{background:var(--surface-2);padding:56px 0 40px;font-size:.95rem;color:var(--muted)}
.foot{display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:32px}
.foot .brand{margin-bottom:12px;color:var(--fg)}
.foot .brand:hover{text-decoration:none}
.foot h2{font-size:.85rem;text-transform:uppercase;letter-spacing:.06em;color:var(--fg);margin:6px 0 14px}
.foot ul{list-style:none;margin:0;padding:0;display:grid;gap:8px}
.foot a{color:var(--muted);text-decoration:none}
.foot a:hover{color:var(--fg);text-decoration:underline}
.legal-line{border-top:1px solid var(--line);margin-top:40px;padding-top:24px;display:flex;flex-wrap:wrap;justify-content:space-between;gap:8px 24px;font-size:.85rem}
@media (max-width:720px){.foot{grid-template-columns:1fr 1fr}.foot>div:first-child{grid-column:1/-1}}

/* Help and legal pages */
.doc{max-width:800px;margin:0 auto;padding:48px 24px 88px}
.doc h1{font-size:clamp(2rem,4vw,2.8rem);letter-spacing:-.03em;line-height:1.12;margin:.2em 0 .4em}
.doc h2{font-size:1.35rem;margin:2.2em 0 .6em;padding-top:1.2em;border-top:1px solid var(--line)}
.doc h3{font-size:1.08rem;margin:1.6em 0 .4em}
.doc li{margin:.3em 0}
.doc .lead{font-size:1.1rem;color:var(--muted)}
.review-banner{display:flex;gap:10px;align-items:center;background:var(--warn-bg);color:var(--warn-fg);border-radius:16px;padding:14px 18px;margin:0 0 24px;font-weight:500}
.review-banner::before{content:"";flex:none;width:10px;height:10px;border-radius:50%;background:currentColor}
.placeholder{background:var(--warn-bg);color:var(--warn-fg);border-radius:4px;padding:0 4px}
.summary{background:var(--surface);border-radius:var(--radius);padding:12px 28px 8px;margin:24px 0}
.summary h2{border:0;margin-top:.8em;padding-top:0}
.toc{background:var(--surface-2);border-radius:20px;padding:16px 24px;margin:24px 0}
.toc ol{padding-left:1.2em;margin:0;columns:2;column-gap:32px}
@media (max-width:640px){.toc ol{columns:1}.doc{padding:32px 16px 64px}.summary{padding:8px 20px 4px}}
.table{overflow-x:auto;background:var(--surface);border-radius:16px;margin:16px 0}
table{border-collapse:collapse;width:100%;font-size:.92rem}
th,td{text-align:left;vertical-align:top;padding:10px 12px;border-bottom:1px solid var(--line)}
tr:last-child td{border-bottom:0}
th{font-weight:600;background:var(--surface-3)}
.qa{display:grid;gap:12px;margin-top:24px}
.qa section{background:var(--surface);border-radius:20px;padding:22px 24px 8px}
.qa h2{border:0;margin:0 0 .4em;padding:0;font-size:1.15rem}

/* Delete-account page */
.card{background:var(--surface);border-radius:var(--radius);padding:24px 28px;margin:20px 0}
.card h2{border:0;margin:0 0 .5em;padding:0;font-size:1.25rem}
.card button{font:500 1rem/1 var(--font);border:0;border-radius:999px;padding:0 22px;min-height:48px;cursor:pointer}
.card .primary{background:var(--ink);color:var(--on-ink)}
.card .danger{background:var(--danger);color:var(--on-danger)}
.card button[disabled]{opacity:.45;cursor:default}
.check{display:flex;gap:12px;align-items:flex-start;margin:16px 0}
.check input{width:20px;height:20px;margin-top:3px;accent-color:var(--ink)}
.field-label{display:block;margin:0 0 6px;font-weight:500}
.field{font:inherit;width:100%;max-width:240px;padding:12px 14px;border:1px solid var(--line);border-radius:12px;background:var(--bg);color:var(--fg);letter-spacing:.08em}
.status{border-radius:14px;padding:12px 16px;margin-top:14px}
.status.ok{background:var(--ok-bg);color:var(--ok-fg)}
.status.err{background:var(--err-bg);color:var(--err-fg)}
[hidden]{display:none!important}

/* 404 */
.notfound{text-align:center;padding:120px 24px 140px}
.notfound .code{font-size:clamp(4rem,12vw,7rem);font-weight:500;letter-spacing:-.05em;color:var(--ink);line-height:1;margin-bottom:12px}
.notfound p{color:var(--muted);margin-bottom:28px}
.cta-row.center{justify-content:center}