:root{
  --ink:#14211f; --muted:#5a6b68; --line:#dfe6e3; --bg:#fbfaf6; --card:#ffffff;
  --teal:#0f3d3e; --teal-2:#1c5f5f; --saffron:#e08a1e; --saffron-soft:#fdf1df; --mint:#e6f2ee;
  --radius:14px; --shadow:0 1px 2px rgba(15,61,62,.06),0 8px 24px rgba(15,61,62,.06);
  --serif:'Fraunces',Georgia,serif; --sans:'Inter',system-ui,-apple-system,'Segoe UI',sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font:16px/1.6 var(--sans);color:var(--ink);background:var(--bg);-webkit-font-smoothing:antialiased}
img{max-width:100%;height:auto}
a{color:var(--teal-2)}
h1,h2,h3{font-family:var(--serif);line-height:1.15;color:var(--teal);margin:0 0 .5em}
h1{font-size:clamp(2rem,5vw,3.4rem);letter-spacing:-.01em}
h2{font-size:clamp(1.6rem,3.2vw,2.3rem)}
h3{font-size:1.2rem}
p{margin:0 0 1em}
.wrap{max-width:1140px;margin:0 auto;padding:0 16px}
.muted{color:var(--muted)}
.skip{position:absolute;left:-999px}.skip:focus{left:8px;top:8px;background:#fff;padding:8px;z-index:99}
.btn{display:inline-flex;align-items:center;gap:.4em;background:var(--teal);color:#fff;text-decoration:none;font-weight:600;padding:.8em 1.3em;border-radius:999px;border:0;cursor:pointer;font-size:1rem;transition:transform .15s,background .15s}
.btn:hover{background:var(--teal-2);transform:translateY(-1px)}
.btn-alt{background:var(--saffron)}.btn-alt:hover{background:#c97712}
.btn-ghost{background:transparent;color:var(--teal);box-shadow:inset 0 0 0 2px var(--teal)}.btn-ghost:hover{background:var(--mint)}
.btn-sm{padding:.5em 1em;font-size:.9rem}
/* nav */
.nav{position:sticky;top:0;z-index:20;background:rgba(251,250,246,.92);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.nav-in{display:flex;align-items:center;justify-content:space-between;height:64px}
.brand{display:flex;align-items:center;gap:.5em;text-decoration:none;color:var(--teal);font-size:1.1rem}
.brand b{font-family:var(--serif)}
#menu{display:flex;align-items:center;gap:1.4em}
#menu a{text-decoration:none;color:var(--ink);font-weight:500}
#menu a.btn{color:#fff}
.nav-toggle{display:none;background:none;border:1px solid var(--line);border-radius:8px;padding:.4em .8em;font:inherit}
@media(max-width:820px){
  .nav-toggle{display:block}
  #menu{display:none;position:absolute;top:64px;left:0;right:0;flex-direction:column;align-items:stretch;gap:0;background:var(--bg);border-bottom:1px solid var(--line);padding:8px 16px 16px}
  #menu.open{display:flex}
  #menu a{padding:.7em 0;border-bottom:1px solid var(--line)}
  #menu a.btn{margin-top:.8em;justify-content:center;border:0}
}
/* hero */
.hero{padding:64px 0 56px;background:radial-gradient(1200px 500px at 85% -10%,var(--saffron-soft),transparent 60%),radial-gradient(900px 500px at -10% 110%,var(--mint),transparent 60%)}
.hero-grid{display:grid;grid-template-columns:1.15fr .85fr;gap:40px;align-items:center}
.eyebrow{display:inline-block;font-size:.8rem;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--saffron);margin-bottom:.8em}
.lead{font-size:1.15rem;color:var(--muted);max-width:36em}
.cta-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:1.4em}
.hero-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);padding:22px}
.hero-card ul{list-style:none;margin:0;padding:0}
.hero-card li{display:flex;gap:12px;padding:12px 0;border-bottom:1px dashed var(--line)}
.hero-card li:last-child{border:0}
.dot{flex:0 0 34px;height:34px;border-radius:10px;display:grid;place-items:center;background:var(--mint);color:var(--teal);font-weight:700}
@media(max-width:820px){.hero-grid{grid-template-columns:1fr}.hero{padding:40px 0}}
/* sections */
section.block{padding:64px 0}
section.alt{background:#fff;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.sec-head{display:flex;justify-content:space-between;align-items:end;gap:16px;margin-bottom:28px;flex-wrap:wrap}
.sec-head p{max-width:40em;margin:0}
.grid{display:grid;gap:20px}
.g3{grid-template-columns:repeat(auto-fill,minmax(260px,1fr))}
.g2{grid-template-columns:repeat(auto-fit,minmax(300px,1fr))}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow);display:flex;flex-direction:column}
.card h3{margin-bottom:.35em}
.card .meta{display:flex;gap:10px;flex-wrap:wrap;font-size:.85rem;color:var(--muted);margin-bottom:.8em}
.tag{display:inline-block;font-size:.75rem;font-weight:600;background:var(--mint);color:var(--teal);padding:.2em .6em;border-radius:999px}
.price{font-family:var(--serif);font-size:1.5rem;color:var(--teal);margin-top:auto;padding-top:.6em}
.card .btn{margin-top:14px;align-self:flex-start}
.feature{display:flex;gap:14px}
.feature .dot{flex-basis:42px;height:42px}
.steps{counter-reset:s;list-style:none;padding:0;margin:0;display:grid;gap:16px;grid-template-columns:repeat(auto-fit,minmax(220px,1fr))}
.steps li{counter-increment:s;background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:20px}
.steps li::before{content:counter(s);display:grid;place-items:center;width:34px;height:34px;border-radius:50%;background:var(--saffron);color:#fff;font-weight:700;margin-bottom:10px}
/* pricing */
.plan{position:relative}
.plan.best{border:2px solid var(--saffron)}
.plan.best::before{content:'Most useful';position:absolute;top:-12px;right:18px;background:var(--saffron);color:#fff;font-size:.75rem;font-weight:600;padding:.2em .7em;border-radius:999px}
.plan ul{padding-left:1.1em;margin:.6em 0 0}
.plan li{margin:.3em 0}
/* teachers */
.person{display:flex;gap:16px;align-items:flex-start}
.avatar{flex:0 0 64px;height:64px;border-radius:50%;display:grid;place-items:center;background:var(--teal);color:#fff;font-family:var(--serif);font-size:1.4rem}
/* faq */
details{background:#fff;border:1px solid var(--line);border-radius:12px;padding:14px 18px;margin-bottom:10px}
summary{cursor:pointer;font-weight:600}
details p{margin:.6em 0 0;color:var(--muted)}
/* forms */
form.f{display:grid;gap:14px}
label{font-weight:500;font-size:.95rem}
input,select,textarea{width:100%;font:inherit;padding:.7em .9em;border:1px solid var(--line);border-radius:10px;background:#fff}
input:focus,select:focus,textarea:focus{outline:2px solid var(--saffron);border-color:transparent}
.hp{position:absolute;left:-5000px}
.notice{padding:12px 16px;border-radius:10px;margin-bottom:16px}
.notice.ok{background:var(--mint);color:var(--teal)}
.notice.err{background:#fde8e6;color:#8a2016}
/* cta band */
.band{background:var(--teal);color:#e6f2ee;border-radius:20px;padding:36px;display:flex;justify-content:space-between;align-items:center;gap:20px;flex-wrap:wrap}
.band h2{color:#fff;margin:0}
/* ads */
.ad{margin:28px auto;max-width:970px;min-height:90px}
/* footer */
.foot{background:#0c2b2c;color:#c9dcd7;padding:48px 0 20px;margin-top:40px}
.foot a{color:#c9dcd7;text-decoration:none;display:block;padding:.2em 0}
.foot a:hover{color:#fff}
.foot .brand{color:#fff;display:flex}
.foot h3{color:#fff;font-family:var(--sans);font-size:.85rem;text-transform:uppercase;letter-spacing:.08em}
.foot .muted{color:#9fb8b2;margin-top:.8em}
.foot-grid{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:28px}
.foot-base{border-top:1px solid #1d4546;margin-top:28px;padding-top:16px;font-size:.85rem;color:#9fb8b2}
@media(max-width:820px){.foot-grid{grid-template-columns:1fr 1fr}}
.wa{position:fixed;right:16px;bottom:16px;background:#1f9d55;color:#fff;text-decoration:none;font-weight:600;padding:.7em 1.1em;border-radius:999px;box-shadow:var(--shadow)}
.prose{max-width:760px}
.prose h2{margin-top:1.4em}
.crumbs{font-size:.85rem;color:var(--muted);margin-bottom:12px}
.crumbs a{color:var(--muted)}
/* updates */
.chips{display:flex;gap:8px;flex-wrap:wrap;margin:18px 0}
.chip{padding:.4em .9em;border-radius:999px;border:1px solid var(--line);background:#fff;text-decoration:none;color:var(--ink);font-size:.9rem}
.chip.on{background:var(--teal);color:#fff;border-color:var(--teal)}
.posts{display:grid;gap:12px;margin-top:10px}
.post{background:#fff;border:1px solid var(--line);border-radius:12px;padding:16px 18px}
.post h2{font-size:1.15rem;margin:.3em 0;font-family:var(--sans);font-weight:600}
.post h2 a{text-decoration:none;color:var(--teal)}
.post h2 a:hover{text-decoration:underline}
.post .meta{display:flex;gap:10px;flex-wrap:wrap;font-size:.82rem;color:var(--muted)}
.post p{margin:.2em 0 0}
.pager{display:flex;gap:14px;align-items:center;justify-content:center;margin-top:24px}
.body{white-space:normal;margin-bottom:1em}
/* calculators */
.calc-grid{display:grid;grid-template-columns:1fr 1fr;gap:24px;align-items:start}
@media(max-width:820px){.calc-grid{grid-template-columns:1fr}}
.calc-out{background:var(--teal);color:#e6f2ee;border-radius:var(--radius);padding:22px}
.calc-out .big{font-family:var(--serif);font-size:2.2rem;color:#fff;line-height:1.1}
.calc-out dl{display:grid;grid-template-columns:1fr auto;gap:8px 16px;margin:16px 0 0}
.calc-out dt{color:#9fc4bc}.calc-out dd{margin:0;text-align:right;font-weight:600;color:#fff}
.bar{height:12px;border-radius:999px;background:#2b6b6b;overflow:hidden;margin-top:14px;display:flex}
.bar i{display:block;height:100%;background:var(--saffron)}
.range-row{display:grid;grid-template-columns:1fr 130px;gap:10px;align-items:center}
input[type=range]{padding:0;accent-color:var(--teal)}
.tool-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:14px}
.tool{display:block;text-decoration:none;color:var(--ink);background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:18px;transition:transform .15s,box-shadow .15s}
.tool:hover{transform:translateY(-2px);box-shadow:var(--shadow)}
.tool b{display:block;font-family:var(--serif);color:var(--teal);font-size:1.1rem}
.keys{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:10px}
.keys button{font:inherit;font-size:1.1rem;padding:.75em 0;border-radius:10px;border:1px solid var(--line);background:#fff;cursor:pointer}
.keys button:hover{background:var(--mint)}
.keys .op{background:var(--mint);color:var(--teal);font-weight:600}
.keys .eq{background:var(--saffron);color:#fff;border-color:var(--saffron)}
.keys.sci{grid-template-columns:repeat(5,1fr)}
.screen{font-family:ui-monospace,Menlo,monospace;font-size:1.8rem;text-align:right;padding:14px 16px;border-radius:12px;background:#0c2b2c;color:#fff;min-height:72px;word-break:break-all}
.screen small{display:block;font-size:.85rem;color:#9fc4bc;min-height:1.2em}
table.t{width:100%;border-collapse:collapse;font-size:.92rem}
table.t th,table.t td{text-align:left;padding:.55em .6em;border-bottom:1px solid var(--line)}
table.t th{font-size:.75rem;text-transform:uppercase;letter-spacing:.05em;color:var(--muted)}
/* homepage v2 */
.hero-v2 h1{max-width:14em}
.stat-row{list-style:none;display:flex;flex-wrap:wrap;gap:22px;padding:0;margin:28px 0 0}
.stat-row li{display:flex;flex-direction:column}
.stat-row b{font-family:var(--serif);font-size:1.7rem;color:var(--teal);line-height:1}
.stat-row span{font-size:.82rem;color:var(--muted)}
.mock-card .mc-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px}
.mc-q{margin:0 0 10px}
.mc-opts{margin:0;padding-left:1.4em;display:grid;gap:6px}
.mc-opts li{padding:.45em .7em;border:1px solid var(--line);border-radius:10px;background:#fff}
.mc-opts li.ok{border-color:#2f9b67;background:#e8f6ee;font-weight:600}
.mc-prog{height:8px;border-radius:999px;background:var(--mint);margin-top:14px;overflow:hidden}
.mc-prog span{display:block;height:100%;background:var(--saffron)}
.exam-grid{grid-template-columns:repeat(auto-fill,minmax(240px,1fr))}
.exam{display:flex;flex-direction:column;gap:4px;text-decoration:none;color:var(--ink);background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:20px;transition:transform .15s,box-shadow .15s,border-color .15s}
.exam:hover{transform:translateY(-2px);box-shadow:var(--shadow);border-color:var(--saffron)}
.exam b{font-family:var(--serif);font-size:1.3rem;color:var(--teal)}
.exam-ico{width:44px;height:44px;border-radius:12px;display:grid;place-items:center;background:var(--saffron-soft);color:#8a5310;font-family:var(--serif);font-size:1.3rem;margin-bottom:6px}
.topics{display:flex;flex-wrap:wrap;gap:6px;margin-top:10px}
.topics i{font-style:normal;font-size:.75rem;background:var(--mint);color:var(--teal);padding:.15em .55em;border-radius:999px}
.tag-soft{background:#eef0ef;color:var(--muted)}
.card .meta .tag{margin-right:0}
.checks{list-style:none;padding:0;margin:0 0 8px}
.checks li{padding:.35em 0 .35em 1.7em;position:relative}
.checks li::before{content:'✓';position:absolute;left:0;top:.35em;width:1.2em;height:1.2em;border-radius:50%;background:var(--mint);color:var(--teal);font-size:.8rem;display:grid;place-items:center;font-weight:700}
.progress-demo .pd-row{display:flex;justify-content:space-between;font-size:.9rem;margin-top:12px}
.pd-bar{height:8px;border-radius:999px;background:var(--mint);overflow:hidden;margin-top:6px}
.pd-bar i{display:block;height:100%;background:var(--teal)}
.pd-scores{display:flex;align-items:flex-end;gap:8px;height:110px;margin-top:10px}
.pd-scores span{flex:1;background:linear-gradient(180deg,var(--saffron),#c97712);border-radius:6px 6px 2px 2px;position:relative}
.pd-scores em{position:absolute;top:-1.3em;left:0;right:0;text-align:center;font-style:normal;font-size:.72rem;color:var(--muted)}
.upd-list{display:grid;gap:10px}
.upd{display:grid;grid-template-columns:auto 1fr auto;gap:12px;align-items:center;text-decoration:none;color:var(--ink);background:#fff;border:1px solid var(--line);border-radius:12px;padding:12px 16px}
.upd:hover{border-color:var(--teal)}
@media(max-width:600px){.upd{grid-template-columns:1fr}.stat-row{gap:16px}}