/* UpOnly Learning — graph-paper calm, navy ink, one yellow step. */
:root{
  --paper:#f5f7fb; --sheet:#ffffff; --grid:#e1e7f1; --ink:#1b2a44; --text:#1b2a44; --muted:#56637c;
  --accent:#2347b8; --accent-ink:#ffffff; --mark:#ffd23f; --line:#d3dbe8; --good:#1d7a4f; --warn:#9a5600;
  --display:"Bricolage Grotesque","Avenir Next","Segoe UI",system-ui,sans-serif;
  --body:"Atkinson Hyperlegible","Segoe UI",system-ui,sans-serif;
  --mono:"JetBrains Mono",ui-monospace,Menlo,monospace;
  color-scheme:light;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--text);font:17px/1.6 var(--body);
  background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);background-size:28px 28px}
a{color:var(--accent)}
img,svg{max-width:100%}
.wrap{max-width:1160px;margin:0 auto;padding-left:max(20px,env(safe-area-inset-left));padding-right:max(20px,env(safe-area-inset-right))}
h1,h2,h3{font-family:var(--display);letter-spacing:-.02em;line-height:1.08;text-wrap:balance;margin:0}
h1{font-size:clamp(40px,7vw,76px);font-weight:800}
h2{font-size:clamp(28px,4.4vw,44px);font-weight:800}
h3{font-size:21px;font-weight:700}
.eyebrow{font:500 12px/1 var(--mono);letter-spacing:.12em;text-transform:uppercase;color:var(--muted)}
.lead{font-size:20px;color:var(--muted);max-width:60ch}
:focus-visible{outline:3px solid var(--accent);outline-offset:2px}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important;animation:none!important}}

/* header */
#site-header{position:sticky;top:0;z-index:20;background:rgba(245,247,251,.94);backdrop-filter:blur(6px);border-bottom:1px solid var(--line);
  display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;padding:12px max(20px,env(safe-area-inset-left))}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);font:800 20px/1 var(--display);letter-spacing:-.02em}
.brand svg{width:34px;height:34px}
.brand b{color:var(--accent)}
.nav{display:flex;align-items:center;gap:16px;flex-wrap:wrap}
.nav>a{color:var(--ink);text-decoration:none;font-weight:700;font-size:15px}
.langs{display:inline-flex;border:1px solid var(--line);border-radius:999px;overflow:hidden}
.langs button{border:0;background:var(--sheet);color:var(--muted);font:600 12px/1 var(--mono);padding:8px 9px;cursor:pointer}
.langs button[aria-pressed="true"]{background:var(--ink);color:#fff}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:46px;padding:0 20px;border-radius:6px;border:0;background:var(--accent);color:var(--accent-ink);
  font:700 16px/1 var(--body);text-decoration:none;cursor:pointer}
.btn:hover{filter:brightness(1.08)}
.btn.sm{min-height:38px;padding:0 14px;font-size:14px}
.btn.ghost{background:transparent;color:var(--ink);box-shadow:inset 0 0 0 1.5px var(--line)}
.btn.mark{background:var(--mark);color:var(--ink)}
.btn[disabled]{opacity:.55;cursor:not-allowed}

/* sections */
section{padding-block:72px}
.hero{padding-block:72px 56px;display:grid;grid-template-columns:minmax(0,1.25fr) minmax(0,1fr);gap:48px;align-items:center}
@media (max-width:860px){.hero{grid-template-columns:minmax(0,1fr)}}
.hero h1 .step{background:linear-gradient(transparent 62%,var(--mark) 62%,var(--mark) 90%,transparent 90%)}
.hero .ctas{display:flex;flex-wrap:wrap;gap:12px;margin-top:28px}
.hero .note{font-size:14px;color:var(--muted);margin-top:10px}
.preview{background:var(--sheet);border:1px solid var(--line);border-radius:10px;padding:22px;box-shadow:0 18px 40px -24px rgba(27,42,68,.35)}
.preview .pv-meta{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:10px}
.pill{font:500 11.5px/1 var(--mono);padding:5px 8px;border-radius:3px;background:var(--paper);border:1px solid var(--line);color:var(--muted)}
.pill.ok{background:#e4f4ec;border-color:#bfe3cf;color:var(--good)}
.pill.soon{background:#fff6d6;border-color:#f1dd8b;color:#6d5300}
.preview h3{margin:4px 0 12px}
.preview ol{margin:0;padding-left:20px;font-size:15px}
.say{border-left:3px solid var(--mark);padding:8px 12px;background:var(--paper);margin:10px 0;font-style:italic;font-size:15px}
.stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin-top:8px}
@media (max-width:640px){.stats{grid-template-columns:repeat(2,minmax(0,1fr))}}
.stat{background:var(--sheet);border:1px solid var(--line);border-radius:8px;padding:16px}
.stat b{display:block;font:800 34px/1 var(--display);font-variant-numeric:tabular-nums}
.stat span{color:var(--muted);font-size:14px}
.steps{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px;margin-top:28px;counter-reset:s}
@media (max-width:860px){.steps{grid-template-columns:minmax(0,1fr)}}
.steps li{list-style:none;counter-increment:s;background:var(--sheet);border:1px solid var(--line);border-radius:8px;padding:22px}
.steps li::before{content:counter(s);display:inline-grid;place-items:center;width:34px;height:34px;border-radius:6px;background:var(--ink);color:var(--mark);font:800 18px/1 var(--display);margin-bottom:12px}
.steps p{color:var(--muted);margin:6px 0 0;font-size:16px}
.subjects{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:10px;margin-top:24px}
.subj{background:var(--sheet);border:1px solid var(--line);border-radius:8px;padding:14px 16px;display:flex;justify-content:space-between;align-items:center;gap:8px;font-weight:700}
.subj.live{border-color:var(--accent);box-shadow:inset 4px 0 0 var(--accent)}
.grades{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin-top:20px}
@media (max-width:760px){.grades{grid-template-columns:minmax(0,1fr)}}
.grade{background:var(--sheet);border:1px solid var(--line);border-radius:8px;padding:16px}
.grade .pill{margin-bottom:8px;display:inline-block}

/* pricing */
.plans{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px;margin-top:28px;align-items:stretch}
@media (max-width:860px){.plans{grid-template-columns:minmax(0,1fr)}}
.plan{background:var(--sheet);border:1px solid var(--line);border-radius:10px;padding:26px;display:flex;flex-direction:column;gap:12px;position:relative}
.plan.best{border:2px solid var(--accent)}
.plan .badge{position:absolute;top:-12px;left:24px;background:var(--mark);color:var(--ink);font:700 12px/1 var(--mono);padding:6px 10px;border-radius:4px;letter-spacing:.04em}
.plan .price{font:800 44px/1 var(--display);font-variant-numeric:tabular-nums}
.plan .per{color:var(--muted);font-size:15px}
.plan ul{margin:0;padding-left:20px;color:var(--text)}
.plan .btn{margin-top:auto}
.plan .msg{font-size:14px;color:var(--warn);min-height:1em}

/* story */
.story{background:var(--sheet);border:1px solid var(--line);border-radius:12px;display:grid;grid-template-columns:minmax(0,300px) minmax(0,1fr);gap:40px;padding:44px}
@media (max-width:860px){.story{grid-template-columns:minmax(0,1fr);padding:26px 20px;gap:18px}}
.story .body{display:flex;flex-direction:column;gap:14px;max-width:64ch}
.story .body p{margin:0}
.story .pull{font:600 22px/1.35 var(--display);border-left:4px solid var(--mark);padding-left:16px}
.story .sig{color:var(--muted);font-style:italic}
.cost{margin-top:20px;display:flex;flex-direction:column;gap:8px;font:500 14px/1.3 var(--mono);color:var(--muted)}
.cost s{color:var(--warn)} .cost b{color:var(--good);font-weight:500}

/* footer */
#site-footer{border-top:1px solid var(--line);background:var(--sheet);padding:28px max(20px,env(safe-area-inset-left)) calc(28px + env(safe-area-inset-bottom));font-size:14px;color:var(--muted)}
#site-footer .foot-links{display:flex;flex-wrap:wrap;gap:14px;margin-bottom:10px}
#site-footer .fine{font-size:12px;max-width:110ch}

/* forms */
.card{background:var(--sheet);border:1px solid var(--line);border-radius:10px;padding:28px;max-width:440px;margin:56px auto}
.field{display:flex;flex-direction:column;gap:6px;margin-bottom:14px}
.field label{font:500 12px/1 var(--mono);letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}
input,select{font:inherit;color:var(--text);background:var(--paper);border:1px solid var(--line);border-radius:6px;padding:11px 12px;width:100%}
.err{color:var(--warn);font-size:15px;min-height:1.2em}
.linkbtn{background:none;border:0;color:var(--accent);font:inherit;cursor:pointer;padding:0;text-decoration:underline}

/* library */
.lib{display:grid;grid-template-columns:320px minmax(0,1fr);gap:22px;padding-block:28px 56px;align-items:start}
@media (max-width:900px){.lib{grid-template-columns:minmax(0,1fr)}}
.panel{background:var(--sheet);border:1px solid var(--line);border-radius:10px;padding:18px;display:flex;flex-direction:column;gap:16px}
.seg{display:grid;grid-template-columns:1fr 1fr;border:1px solid var(--line);border-radius:6px;overflow:hidden}
.seg button{border:0;background:var(--paper);padding:10px;font:700 14px/1.2 var(--body);color:var(--text);cursor:pointer}
.seg button[aria-pressed="true"]{background:var(--ink);color:#fff}
.chips{display:flex;flex-wrap:wrap;gap:6px}
.chips button{border:1px solid var(--line);background:var(--paper);border-radius:999px;padding:7px 11px;font:600 14px/1 var(--body);color:var(--text);cursor:pointer}
.chips button[aria-pressed="true"]{border-color:var(--accent);box-shadow:inset 0 0 0 1px var(--accent)}
.chips button[disabled]{opacity:.5;cursor:not-allowed}
.chips button small{font-size:10px;font-weight:500;color:var(--muted);margin-left:4px}
.topics{display:flex;flex-direction:column;border:1px solid var(--line);border-radius:6px;max-height:420px;overflow:auto;background:var(--paper)}
.topic{display:grid;grid-template-columns:auto 1fr;gap:2px 10px;padding:9px 11px;border:0;border-bottom:1px solid var(--line);background:none;text-align:left;font:inherit;color:var(--text);cursor:pointer}
.topic:last-child{border-bottom:0}
.topic .code{font:500 11px/1.6 var(--mono);color:var(--accent);grid-row:span 2;min-width:70px}
.topic .t{font-weight:700;font-size:15px;line-height:1.3}
.topic .d{font-size:13px;color:var(--muted);line-height:1.35}
.topic[aria-pressed="true"]{background:var(--sheet);box-shadow:inset 4px 0 0 var(--accent)}
.sheet{background:var(--sheet);border:1px solid var(--line);border-radius:10px;min-width:0;position:relative;overflow:hidden}
.sheet-head{padding:22px 24px 0;display:flex;flex-direction:column;gap:10px}
.banner{margin:16px 24px 0;padding:12px 14px;border-radius:6px;background:#fff6d6;border:1px solid #f1dd8b;display:flex;flex-wrap:wrap;gap:10px;align-items:center;justify-content:space-between;font-size:15px}
.banner.ok{background:#e4f4ec;border-color:#bfe3cf}
.tabs{display:flex;gap:2px;border-bottom:1px solid var(--line);padding:0 24px;margin-top:14px;overflow-x:auto}
.tabs button{border:0;background:none;padding:12px;font:700 15px/1 var(--body);color:var(--muted);border-bottom:3px solid transparent;cursor:pointer;white-space:nowrap}
.tabs button[aria-selected="true"]{color:var(--ink);border-color:var(--accent)}
.content{padding:20px 24px 32px;max-width:78ch;position:relative}
.content h3{margin:22px 0 8px;display:flex;gap:10px;align-items:baseline;flex-wrap:wrap}
.content h3 .min{font:500 12px/1 var(--mono);color:var(--muted)}
.content ul,.content ol{padding-left:22px;margin:0 0 10px}
.ex{border:1px dashed var(--line);border-radius:6px;padding:10px 12px;margin:8px 0}
.ex .q{font-weight:700}
.miss{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:10px;margin:6px 0}
@media (max-width:560px){.miss{grid-template-columns:minmax(0,1fr)}}
.miss div{background:var(--paper);border-radius:6px;padding:10px 12px;font-size:15px}
.miss .k{display:block;font:500 11px/1 var(--mono);text-transform:uppercase;letter-spacing:.06em;margin-bottom:4px}
.miss .wrong .k{color:var(--warn)} .miss .fix .k{color:var(--good)}
.problems{list-style:none;padding:0;counter-reset:p}
.problems li{counter-increment:p;display:grid;grid-template-columns:34px minmax(0,1fr);gap:8px;padding:12px 0;border-bottom:1px solid var(--line)}
.problems li::before{content:counter(p);font:800 19px/1.3 var(--display);color:var(--accent)}
.problems .lvl{font:500 10.5px/1 var(--mono);text-transform:uppercase;letter-spacing:.06em;color:var(--muted);margin-left:6px}
.problems .work{height:60px;border-bottom:1px dotted var(--line);margin-top:6px}
.ans{color:var(--good);font-weight:700}
.empty{padding:48px 24px;text-align:center;color:var(--muted)}
.gate{padding:48px 24px;text-align:center;display:flex;flex-direction:column;align-items:center;gap:12px}
.gate p{color:var(--muted);max-width:46ch;margin:0}

/* trial protection */
.locked .content{user-select:none;-webkit-user-select:none}
.wm{position:absolute;inset:0;pointer-events:none;overflow:hidden;z-index:2}
.wm span{position:absolute;white-space:nowrap;transform:rotate(-24deg);font:600 15px/1 var(--mono);color:rgba(27,42,68,.07)}
.print-only{display:none}
@media print{
  body{background:#fff}
  #site-header,#site-footer,.panel,.tabs,.banner,.no-print{display:none!important}
  .lib{display:block;padding:0}
  .sheet{border:0}
  .print-only{display:block;font-size:11px;color:#444;margin-top:18px}
  .locked .content,.locked .sheet-head{display:none!important}
  .locked::after{content:"Printing is available with a UpOnly Learning plan.";display:block;padding:40px;font:700 18px/1.4 sans-serif}
}

/* honest live counters on the home page */
.livebox{margin-top:22px;padding:18px 20px;border:1px solid var(--line);border-radius:12px;background:var(--sheet)}
.livebox .eyebrow{display:flex;align-items:center;gap:8px;margin:0 0 6px}
.livebox .dot{width:8px;height:8px;border-radius:50%;background:#2e9461;box-shadow:0 0 0 4px rgba(46,148,97,.18)}
.liveticker{margin:12px 0 0;font-weight:700}
.livenote{margin:8px 0 0;color:var(--muted);font-size:13px}

/* ---- accessibility: minimum target size (WCAG 2.2 AA, 24x24 CSS px) ----
   The navigation and footer links were 22px tall and the checkboxes 20px square,
   which is under the minimum and genuinely hard to hit on a phone or with a tremor.
   Raising the hit area rather than the font keeps the layout as designed. */
.nav a, #site-footer .foot-links a, .langs button, .crumbs a, .toc a {
  display: inline-flex; align-items: center; min-height: 24px;
}
input[type="checkbox"], input[type="radio"] {
  box-sizing: border-box; padding: 0; margin: 0;
  width: 24px; height: 24px; min-width: 24px; min-height: 24px; flex: none;
  accent-color: var(--accent); cursor: pointer;
}
/* A visible focus ring on every interactive element, for anyone navigating by keyboard. */
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible,
textarea:focus-visible, summary:focus-visible, [tabindex]:focus-visible {
  outline: 3px solid var(--accent); outline-offset: 2px; border-radius: 4px;
}


/* A gated free download: the page is public, the file needs a verified account. */
.lockword{font-size:12px;color:var(--muted);font-weight:600}
.lockmark{color:var(--muted)}

/* A download whose file is not on the host yet: looks like the button, does nothing. */
.soonfile{opacity:.6;cursor:default}
a.dl.soonfile,span.dl.soonfile{display:inline-flex;align-items:center;pointer-events:none}