/* Landing page only. A calm study-notebook look: pale sage paper, deep green-grey ink, a quiet green accent,
   and a highlighter yellow reserved for "key" questions (they really come from highlighted course passages). */
:root{
  --paper:#f2f5f1; --sheet:#fbfcfa; --ink:#1f2b27; --soft:#56655f; --rule:#d5ddd8;
  --green:#2e6b59; --green-ink:#ffffff; --green-soft:#dcebe4; --mark:#f3e48a; --wrong:#a34a3c; --wrong-soft:#f6e3df;
  --serif:"Source Serif 4",Georgia,"Times New Roman",serif;
  --sans:"Source Sans 3",system-ui,-apple-system,"Segoe UI",sans-serif;
  color-scheme:light;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --paper:#131a17; --sheet:#1a2320; --ink:#e3eae6; --soft:#9aa9a3; --rule:#2c3833;
  --green:#7fc3ad; --green-ink:#0e1714; --green-soft:#1f3a31; --mark:#5c5426; --wrong:#e99a8b; --wrong-soft:#3a221e;
  color-scheme:dark}}
:root[data-theme="dark"]{
  --paper:#131a17; --sheet:#1a2320; --ink:#e3eae6; --soft:#9aa9a3; --rule:#2c3833;
  --green:#7fc3ad; --green-ink:#0e1714; --green-soft:#1f3a31; --mark:#5c5426; --wrong:#e99a8b; --wrong-soft:#3a221e;
  color-scheme:dark}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font:17px/1.6 var(--sans);-webkit-font-smoothing:antialiased}
a{color:var(--green)}
a:focus-visible,button:focus-visible,summary:focus-visible{outline:2px solid var(--green);outline-offset:3px;border-radius:4px}
.page{max-width:1040px;margin:0 auto;padding:0 max(20px,env(safe-area-inset-left,0px))}

/* top bar */
.bar{display:flex;align-items:center;gap:10px;padding:18px 0}
.name{font:600 21px/1 var(--serif);color:var(--ink);text-decoration:none;margin-right:auto}
.bar .lang,.theme-toggle{font:600 13px var(--sans);color:var(--soft);background:none;border:1px solid var(--rule);border-radius:99px;height:34px;min-width:34px;padding:0 10px;cursor:pointer;display:inline-grid;place-items:center}
.bar .lang:hover,.theme-toggle:hover{color:var(--ink);border-color:var(--soft)}
.link-quiet{color:var(--ink);font-weight:600;text-decoration:none;padding:6px 4px}
.link-quiet:hover{text-decoration:underline}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:48px;padding:0 22px;border-radius:12px;font:600 16px var(--sans);text-decoration:none;border:1.5px solid var(--rule);color:var(--ink);background:var(--sheet);cursor:pointer}
.btn:hover{border-color:var(--soft)}
.btn.go{background:var(--green);border-color:var(--green);color:var(--green-ink)}
.btn.go:hover{filter:brightness(1.06)}

/* hero: words left, a real question right */
.hero{display:grid;grid-template-columns:1.05fr 1fr;gap:56px;align-items:start;padding:48px 0 72px}
@media (max-width:860px){.hero{grid-template-columns:1fr;gap:36px;padding:24px 0 56px}}
h1{font:600 clamp(36px,5.2vw,56px)/1.06 var(--serif);letter-spacing:-.01em;margin:0 0 20px;text-wrap:balance}
.lead{font-size:19px;color:var(--soft);margin:0 0 28px;max-width:34em}
.ctas{display:flex;gap:12px;flex-wrap:wrap}
.reassure{margin:18px 0 0;color:var(--soft);font-size:15px}

/* the sample question, like a page from an exam sheet */
.sheet{background:var(--sheet);border:1px solid var(--rule);border-radius:18px;padding:26px 26px 22px;box-shadow:0 1px 0 var(--rule),0 18px 40px -28px rgba(20,40,30,.35)}
.sheet .from{font-size:14px;color:var(--soft);margin:0 0 10px}
.sheet .q{font:500 21px/1.4 var(--serif);margin:0 0 18px}
.opts{display:grid;gap:8px;margin:0;padding:0;list-style:none}
.opt{width:100%;text-align:left;display:grid;grid-template-columns:28px 1fr;gap:10px;align-items:start;background:none;border:1.5px solid var(--rule);border-radius:12px;padding:11px 14px;font:16px/1.4 var(--sans);color:var(--ink);cursor:pointer}
.opt:hover:not(:disabled){border-color:var(--green)}
.opt .k{width:26px;height:26px;border-radius:50%;border:1.5px solid var(--rule);display:grid;place-items:center;font-size:13px;font-weight:600;color:var(--soft)}
.opt.right{border-color:var(--green);background:var(--green-soft)}
.opt.right .k{background:var(--green);border-color:var(--green);color:var(--green-ink)}
.opt.wrong{border-color:var(--wrong);background:var(--wrong-soft)}
.opt.wrong .k{background:var(--wrong);border-color:var(--wrong);color:#fff}
.opt:disabled{cursor:default}
.why{margin:16px 0 0;font-size:15.5px;line-height:1.55}
.why b{font-weight:600}
.sheet .after{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap;margin-top:16px;font-size:15px}
.mark{background:linear-gradient(transparent 55%,var(--mark) 55%);padding:0 .1em}
@media (prefers-reduced-motion:no-preference){.why{animation:in .25s ease-out}@keyframes in{from{opacity:0;transform:translateY(4px)}}}

/* text sections */
section.s{padding:56px 0;border-top:1px solid var(--rule)}
.cols{display:grid;grid-template-columns:300px 1fr;gap:48px}
@media (max-width:860px){.cols{grid-template-columns:1fr;gap:16px}}
h2{font:600 30px/1.15 var(--serif);margin:0;text-wrap:balance}
.s p{margin:0 0 14px;max-width:38em}
.s p.soft{color:var(--soft)}
.facts{display:flex;flex-wrap:wrap;gap:10px 28px;margin:0 0 18px;padding:0;list-style:none}
.facts li{font-size:17px}
.facts b{font:600 26px/1 var(--serif);margin-right:6px}

dl.gets{margin:0;display:grid;grid-template-columns:1fr 1fr;gap:22px 36px}
@media (max-width:640px){dl.gets{grid-template-columns:1fr}}
dl.gets dt{font-weight:600;margin:0 0 4px}
dl.gets dd{margin:0;color:var(--soft)}

ul.topics{margin:0;padding:0;list-style:none;columns:2;column-gap:36px}
@media (max-width:640px){ul.topics{columns:1}}
ul.topics li{padding:7px 0;border-bottom:1px dashed var(--rule);break-inside:avoid}

ol.steps{margin:0 0 22px;padding:0;list-style:none;counter-reset:s;display:grid;gap:18px}
ol.steps li{counter-increment:s;display:grid;grid-template-columns:40px 1fr;gap:6px 14px}
ol.steps li::before{content:counter(s);grid-row:span 2;width:34px;height:34px;border-radius:50%;border:1.5px solid var(--green);color:var(--green);display:grid;place-items:center;font:600 16px var(--serif)}
ol.steps b{font-weight:600}
ol.steps span{color:var(--soft)}

.aside{border-left:3px solid var(--green);padding:6px 0 6px 22px}

.faq details{border-bottom:1px solid var(--rule);padding:14px 0}
.faq details:first-child{border-top:1px solid var(--rule)}
.faq summary{cursor:pointer;font-weight:600;list-style:none;display:flex;justify-content:space-between;gap:16px}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";color:var(--soft);font-weight:400}
.faq details[open] summary::after{content:"–"}
.faq p{margin:8px 0 0;color:var(--soft)}

footer.end{padding:36px 0 48px;border-top:1px solid var(--rule);color:var(--soft);font-size:14.5px;display:grid;gap:10px}
footer.end nav{display:flex;flex-wrap:wrap;gap:6px 18px}
footer.end a{color:var(--soft)}