/* OBC Study — shared styles (homepage "modern" direction) */
:root{
  --ink:#0F172A; --ink-2:#334155; --muted:#475569; --faint:#64748B;
  --line:#E6EAF2; --line-2:#EEF1F6; --bg:#FFFFFF; --bg-soft:#F8FAFC; --bg-tint:#F1F5FF;
  --brand:#3350E0; --brand-dark:#2238B8; --brand-ink:#1E2F8F; --brand-chip:#E3E9FF;
  --ok:#22A06B; --ok-bg:#E6F8EF; --ok-ink:#0B5E3B;
  --bad:#D14343; --bad-bg:#FFF1F1; --bad-ink:#8F1D1D;
  --warn-bg:#FFF4DB; --warn-ink:#7A4E00;
  --t-blue:#EAF1FF; --t-blue-ink:#1E40AF;
  --t-green:#E6F8EF; --t-green-ink:#0B6B45;
  --t-purple:#F1EBFF; --t-purple-ink:#5B2DB0;
  --t-orange:#FFEFE6; --t-orange-ink:#9A3B12;
  --t-yellow:#FFF7DA; --t-yellow-ink:#7A5600;
  --t-pink:#FDEBF2; --t-pink-ink:#9D1F4A;
  --navy:#0F172A; --navy-2:#1E2A47;
  --r-lg:22px; --r-md:16px; --r-sm:12px;
  --shadow:0 1px 2px rgba(15,23,42,.06),0 12px 32px rgba(51,80,224,.10);
  --wrap:1280px;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:88px}
body{margin:0;background:var(--bg);color:var(--ink);font-family:'Plus Jakarta Sans','Segoe UI',system-ui,-apple-system,sans-serif;font-size:17px;line-height:1.65}
img,svg{max-width:100%}
a{color:var(--brand)}a:hover{color:var(--brand-dark)}
h1,h2,h3{margin:0;font-weight:800;letter-spacing:-.025em;line-height:1.12}
p{margin:0}
button{font:inherit;color:inherit}
:focus-visible{outline:3px solid var(--brand);outline-offset:2px;border-radius:6px}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.wrap{max-width:var(--wrap);margin:0 auto;padding:0 40px}
.mono{font-family:ui-monospace,'SF Mono',Menlo,Consolas,monospace;font-size:.92em}

/* header */
.site-head{position:sticky;top:0;z-index:20;background:var(--glass,rgba(255,255,255,.96));backdrop-filter:saturate(1.4) blur(8px);border-bottom:1px solid var(--line-2)}
.site-head .wrap{height:76px;display:flex;align-items:center;gap:28px}
.brand{font-size:24px;font-weight:800;letter-spacing:-.02em;color:var(--ink);text-decoration:none;white-space:nowrap}
.brand:hover{color:var(--ink)}
.nav{display:flex;gap:4px;font-size:15px}
.nav a{padding:10px 14px;text-decoration:none;color:var(--faint);border-radius:999px;white-space:nowrap}
.nav a:hover{color:var(--ink);background:var(--bg-soft)}
.nav a[aria-current=page]{color:var(--brand);font-weight:700}
/* Menu text sits on the logo's baseline (measured: 9.5px lower than centred at 15px text, 10px at the 14px mid-width size) */
@media (min-width:861px){.site-head .nav{position:relative;top:9.5px}}
@media (min-width:861px) and (max-width:1180px){.site-head .nav{top:10px}}
/* "Learn" drop-down in the top bar */
.nav-dd{position:relative;display:flex}
.nav-dd-btn{font:inherit;display:inline-flex;align-items:center;gap:6px;padding:10px 14px;border:0;background:none;color:var(--faint);border-radius:999px;cursor:pointer;white-space:nowrap}
.nav-dd-btn:hover,.nav-dd.open .nav-dd-btn{color:var(--ink);background:var(--bg-soft)}
.nav-dd.is-current .nav-dd-btn{color:var(--brand);font-weight:700}
.nav-dd-btn svg{transition:transform .15s}
.nav-dd.open .nav-dd-btn svg{transform:rotate(180deg)}
.nav-dd-menu{display:none;position:absolute;top:calc(100% + 8px);left:0;min-width:220px;flex-direction:column;gap:2px;padding:6px;background:var(--surface,#fff);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow);z-index:30}
.nav-dd-menu::before{content:"";position:absolute;left:0;right:0;top:-10px;height:10px}
.nav-dd-menu a{border-radius:10px}
.nav-dd.open .nav-dd-menu{display:flex}
@media (hover:hover) and (min-width:861px){.nav-dd:hover .nav-dd-menu{display:flex}.nav-dd:hover .nav-dd-btn svg{transform:rotate(180deg)}}
.head-spacer{flex-grow:1}
.head-cta{font-size:15px}
.menu-btn{display:none;width:44px;height:44px;border:1px solid var(--line);background:var(--surface,#fff);border-radius:12px;align-items:center;justify-content:center;cursor:pointer}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:48px;padding:0 24px;border-radius:999px;font-weight:600;text-decoration:none;border:1px solid transparent;cursor:pointer;font-size:16px;line-height:1.2;white-space:nowrap}
.btn-lg{min-height:54px;padding:0 26px}
.btn-sm{min-height:40px;padding:0 16px;font-size:14px}
.btn-primary{background:var(--brand-btn);color:#fff}.btn-primary:hover{background:var(--brand-btn-h);color:#fff}
.btn-outline{background:var(--surface,#fff);color:var(--brand);border-color:var(--brand)}.btn-outline:hover{background:var(--bg-tint)}
.btn-ghost{background:var(--surface,#fff);color:var(--ink);border-color:var(--line-3,#CBD5E1)}.btn-ghost:hover{background:var(--bg-soft);color:var(--ink)}
.btn-white{background:var(--surface,#fff);color:var(--brand-ink)}.btn-white:hover{background:var(--bg-tint)}
.btn[disabled]{opacity:.45;cursor:not-allowed}

.chip{display:inline-flex;align-items:center;gap:6px;padding:6px 14px;border-radius:999px;background:var(--brand-chip);color:var(--brand-ink);font-size:13px;font-weight:700;line-height:1.3}
.tag{display:inline-flex;padding:2px 10px;border:1px solid var(--line);border-radius:999px;font-size:12px;color:var(--muted);font-weight:600}
.pill{display:inline-flex;align-items:center;padding:4px 12px;border-radius:999px;font-size:12px;font-weight:700;white-space:nowrap}
.pill-none{background:var(--chip-bg,#F1F5F9);color:var(--muted)}
.pill-read{background:var(--brand-chip);color:var(--brand-ink)}
.pill-part{background:var(--warn-bg);color:var(--warn-ink)}
.pill-done{background:var(--ok-bg);color:var(--ok-ink)}

/* sections */
.section{padding:96px 0 0}
.section-head{display:flex;flex-direction:column;gap:14px;max-width:820px;margin-bottom:40px}
.section-head h2{font-size:44px}
.lead{font-size:20px;color:var(--muted)}
.muted{color:var(--muted)}.faint{color:var(--faint)}
.small{font-size:14px}.xs{font-size:13px}

.hero{background:var(--bg-tint);padding:96px 0 88px}
.hero .wrap{display:grid;grid-template-columns:minmax(0,1.05fr) minmax(0,1fr);gap:64px;align-items:center}
.hero h1{font-size:64px;line-height:1.05;letter-spacing:-.035em}
.hero-copy{display:flex;flex-direction:column;gap:24px;align-items:flex-start}
.btn-row{display:flex;gap:12px;flex-wrap:wrap}

.card{background:var(--surface,#fff);border:1px solid var(--line);border-radius:var(--r-lg);padding:30px}
.card-float{border:none;box-shadow:var(--shadow)}
.grid-4{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:20px}
.grid-3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}
.grid-2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
.tile{border-radius:var(--r-lg);padding:30px;display:flex;flex-direction:column;gap:12px}
.tile h3{font-size:22px;letter-spacing:-.01em}
.tile p{font-size:15px;color:var(--muted)}
.num{width:44px;height:44px;border-radius:14px;background:var(--surface,#fff);display:flex;align-items:center;justify-content:center;font-weight:800}
.t-blue{background:var(--t-blue)}.t-blue .num,.t-blue .k{color:var(--t-blue-ink)}
.t-green{background:var(--t-green)}.t-green .num,.t-green .k{color:var(--t-green-ink)}
.t-purple{background:var(--t-purple)}.t-purple .num,.t-purple .k{color:var(--t-purple-ink)}
.t-orange{background:var(--t-orange)}.t-orange .num,.t-orange .k{color:var(--t-orange-ink)}
.t-yellow{background:var(--t-yellow)}.t-yellow .num,.t-yellow .k{color:var(--t-yellow-ink)}
.t-pink{background:var(--t-pink)}.t-pink .num,.t-pink .k{color:var(--t-pink-ink)}

.dark-band{background:var(--navy);border-radius:28px;padding:56px;display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.1fr);gap:56px;align-items:center;color:#fff}
.dark-band h2{font-size:40px;color:#fff}
.dark-band p{color:#B6C2D9}
.dark-chip{background:var(--navy-2);color:#8FB4FF}
.dark-tile{background:var(--navy-2);border-radius:16px;padding:18px 20px;font-weight:700}
.cta-band{background:var(--brand-btn);border-radius:28px;padding:56px;display:flex;justify-content:space-between;align-items:center;gap:40px;color:#fff}
.cta-band h2{font-size:40px;color:#fff}.cta-band p{color:var(--brand-chip,#D9E0FF)}

.site-foot{margin-top:96px;padding:40px 0;border-top:1px solid var(--line-2);background:var(--bg-soft);font-size:14px;color:var(--faint)}
.site-foot .wrap{display:flex;justify-content:space-between;gap:40px}
.site-foot nav{display:flex;gap:24px;flex-wrap:wrap}
.site-foot a{color:var(--faint)}

/* sample question (home hero) */
.opt{display:flex;gap:12px;align-items:center;padding:12px 14px;border:1px solid var(--line);border-radius:14px;font-size:15px;background:var(--surface,#fff);text-align:left;width:100%}
.opt .key{flex:0 0 auto;width:28px;height:28px;border-radius:8px;background:var(--chip-bg,#F1F5F9);display:inline-flex;align-items:center;justify-content:center;font-weight:700;font-size:13px}
button.opt{cursor:pointer}
button.opt:hover:not([disabled]){border-color:var(--brand-line,#A5B4FC);background:var(--bg-soft,#FAFBFF)}
.opt.is-picked{border:2px solid var(--brand);background:var(--bg-tint);padding:11px 13px}
.opt.is-picked .key{background:var(--brand-btn);color:#fff}
.opt.is-right{border:2px solid var(--ok);background:var(--ok-bg);color:var(--ok-ink);padding:11px 13px}
.opt.is-right .key{background:var(--ok);color:#fff}
.opt.is-wrong{border:2px solid var(--bad);background:var(--bad-bg);color:var(--bad-ink);padding:11px 13px}
.opt.is-wrong .key{background:var(--bad);color:#fff}
.opt .flag{margin-left:auto;font-size:13px;font-weight:700;white-space:nowrap;padding-left:8px}
.opt[disabled]{cursor:default}

/* ---------- Learn: lessons index ---------- */
.page-head{background:var(--bg-tint);padding:56px 0 40px}
.page-head h1{font-size:52px;letter-spacing:-.035em}
.page-head .wrap{display:flex;flex-direction:column;gap:16px}
.crumbs{font-size:14px;color:var(--faint);display:flex;gap:8px;flex-wrap:wrap}
.crumbs a{color:var(--faint)}
.toolbar{display:flex;gap:12px;flex-wrap:wrap;align-items:center;margin-top:8px}
.search{display:flex;align-items:center;gap:8px;border:1px solid var(--line-3,#CBD5E1);border-radius:999px;padding:0 16px;height:48px;background:var(--surface,#fff);min-width:320px}
.search input{border:none;outline:none;font:inherit;font-size:15px;flex-grow:1;background:transparent;color:var(--ink);min-width:0}
.filter{min-height:40px;padding:0 16px;border-radius:999px;border:1px solid var(--line-3,#CBD5E1);background:var(--surface,#fff);font-size:14px;font-weight:600;cursor:pointer;color:var(--ink-2)}
.filter[aria-pressed=true]{background:var(--ink);color:var(--surface,#fff);border-color:var(--ink)}
.learn-grid{display:grid;grid-template-columns:minmax(0,1fr) 320px;gap:32px;align-items:start;padding-top:40px}
.continue{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:24px;align-items:center;border:2px solid var(--brand);background:var(--surface,#fff);border-radius:var(--r-lg);padding:26px 28px;margin-bottom:24px}
.bar{height:8px;background:var(--line-2,#E2E8F0);border-radius:999px;overflow:hidden;display:flex}
.bar>span{display:block;height:100%}
.group{border:1px solid var(--line);border-radius:var(--r-lg);overflow:hidden;background:var(--surface,#fff);margin-bottom:20px}
.group-head{display:flex;justify-content:space-between;align-items:center;gap:16px;padding:22px 26px}
.group-head h2{font-size:26px}
.lrow{display:grid;grid-template-columns:120px minmax(0,1fr) auto auto;gap:18px;align-items:center;padding:18px 26px;border-top:1px solid var(--line-2)}
.lrow:hover{background:var(--bg-soft,#FAFBFF)}
.lrow .ref{font-weight:700;color:var(--brand);font-size:15px}
.lrow .t{font-weight:700;color:var(--ink);text-decoration:none}
.lrow .t:hover{color:var(--brand)}
.lrow .d{font-size:14px;color:var(--muted);margin-top:2px}
.srow{display:grid;grid-template-columns:120px minmax(0,1fr) auto;gap:18px;align-items:center;padding:14px 26px;border-top:1px solid var(--line-2);color:var(--muted)}
.srow .ref{font-weight:700;color:var(--faint);font-size:15px}
.srow .t{font-weight:600;color:var(--ink-2)}
.soon{padding:22px 26px;border-top:1px solid var(--line-2);color:var(--faint);font-size:15px}
.side{display:flex;flex-direction:column;gap:16px;position:sticky;top:96px}
.side .card{padding:22px}
.eyebrow{font-size:12px;letter-spacing:.08em;text-transform:uppercase;font-weight:700;color:var(--faint)}
.kv{display:flex;justify-content:space-between;font-size:15px;padding:4px 0}
.steps-ol{margin:0;padding-left:20px;font-size:15px;color:var(--ink-2);display:flex;flex-direction:column;gap:4px}

/* ---------- Lesson page ---------- */
.wrap.wide{max-width:1400px}
.lesson-grid{display:grid;grid-template-columns:210px minmax(0,1fr) 250px;gap:36px;align-items:start;padding-top:32px}
.toc{position:sticky;top:96px;display:flex;flex-direction:column;gap:2px;font-size:14px}
.toc a{padding:8px 12px;border-radius:10px;color:var(--muted);text-decoration:none;display:flex;gap:10px;align-items:center}
.toc a:hover{background:var(--bg-soft);color:var(--ink)}
.toc a.is-active{background:var(--bg-tint);color:var(--brand);font-weight:700}
.toc .dot{width:8px;height:8px;border-radius:999px;background:var(--line-3,#CBD5E1);flex:0 0 auto}
.toc a.is-seen .dot{background:var(--ok)}
.lesson-title h1{font-size:46px;letter-spacing:-.03em;margin:8px 0 14px}
.meta{display:flex;gap:8px;flex-wrap:wrap}
.block{border-radius:var(--r-lg);padding:32px;margin-top:24px;scroll-margin-top:96px;border:1px solid var(--line);background:var(--surface,#fff)}
.block.tinted{border:none}
.block-k{display:flex;align-items:center;gap:10px;font-size:13px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;margin-bottom:10px}
.block-k .n{width:28px;height:28px;border-radius:9px;background:var(--surface,#fff);display:inline-flex;align-items:center;justify-content:center;font-size:13px}
.block h2{font-size:28px;margin-bottom:14px}
.block p+p{margin-top:12px}
.block .prose{max-width:68ch}
.field{display:flex;flex-direction:column;gap:6px;margin-top:16px}
.field label{font-weight:600;font-size:16px}
.field input{height:48px;border:1px solid #C8BEEA;border-radius:12px;padding:0 14px;font:inherit;font-size:16px;background:var(--surface,#fff);max-width:420px;width:100%}
.reveal{margin-top:10px;font-size:15px;padding:12px 14px;border-radius:12px;background:var(--surface,#fff)}
.mapgrid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.mapcell{background:var(--surface,#fff);border-radius:14px;padding:14px 16px}
.mapcell .r{font-weight:800;color:var(--t-yellow-ink);font-size:14px}
.mapcell .h{font-weight:700}
.mapcell .l{font-size:14px;color:var(--muted)}
.mapgrid.is-hidden .mapcell .h,.mapgrid.is-hidden .mapcell .l{filter:blur(6px);user-select:none}
.rules{border:1px solid var(--line);border-radius:14px;overflow:hidden}
.rule{display:grid;grid-template-columns:220px minmax(0,1fr);gap:20px;padding:14px 18px;border-top:1px solid var(--line-2);font-size:15px}
.rule:first-child{border-top:none}
.rule>div:first-child{display:flex;flex-direction:column;gap:2px}
.rule .w{font-weight:800;color:var(--brand);font-size:14px}
.rule .v{font-weight:600}
.rule ul{margin:0;padding-left:18px;font-weight:600;display:flex;flex-direction:column;gap:2px}
.rule .x{color:var(--muted);font-size:14px;margin-top:4px}
.rule .x b{color:var(--warn-ink);font-weight:700}
.table-scroll{overflow-x:auto}
.figure{background:var(--bg-soft);border-radius:16px;padding:20px;overflow-x:auto}
.figure svg{display:block;margin:0 auto;height:auto}
.figcap{font-size:14px;color:var(--muted);margin-top:10px}
.qa{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin-top:16px}
.qa div{background:var(--bg-soft);border-radius:14px;padding:16px}
.qa b{display:block;margin-bottom:4px}
.qa span{font-size:14px;color:var(--muted)}
.traps{margin:0;padding:0;list-style:none;display:flex;flex-direction:column;gap:10px}
.traps li{background:var(--bg-soft);border-radius:14px;padding:14px 16px}
.traps b{font-weight:700}
.check-cta{background:var(--navy);color:#fff;border:none}
.check-cta h2{color:#fff}
.check-cta p{color:#B6C2D9}
.pager{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin-top:24px}
.pager a{border:1px solid var(--line);border-radius:var(--r-md);padding:16px 20px;text-decoration:none;color:var(--ink)}
.pager a:hover{border-color:var(--brand)}
.pager .s{font-size:13px;color:var(--faint)}
.pager .t{font-weight:700}
.pager .next{text-align:right}
.aside-card{border:1px solid var(--line);border-radius:var(--r-md);padding:20px;display:flex;flex-direction:column;gap:10px;background:var(--surface,#fff)}
.lesson-side{position:sticky;top:96px;display:flex;flex-direction:column;gap:16px}
.defs{display:flex;flex-wrap:wrap;gap:8px}
.defs span{padding:5px 12px;border:1px solid var(--line);border-radius:999px;font-size:13px}

/* ---------- Check page ---------- */
.check-head{background:var(--surface,#fff);border-bottom:1px solid var(--line-2);position:sticky;top:0;z-index:20}
.check-head .wrap{min-height:76px;display:flex;align-items:center;gap:20px;flex-wrap:wrap;padding-top:10px;padding-bottom:10px}
.closed{display:inline-flex;align-items:center;gap:8px;min-height:36px;padding:0 14px;border-radius:999px;background:var(--chip-bg,#F1F5F9);color:var(--ink-2);font-size:14px;font-weight:600}
.closed.open{background:var(--ok-bg);color:var(--ok-ink)}
.check-grid{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:40px;align-items:start;padding-top:40px;max-width:1160px}
.progress3{list-style:none;margin:16px 0 0;padding:0;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px}
.progress3 li{display:flex;flex-direction:column;gap:6px;font-size:13px;font-weight:600;color:var(--faint)}
.progress3 li span{height:8px;border-radius:999px;background:var(--line-2,#E2E8F0)}
.progress3 li.now{color:var(--brand)}.progress3 li.now span{background:var(--brand-btn)}
.progress3 li.ok{color:var(--ok-ink)}.progress3 li.ok span{background:var(--ok)}
.progress3 li.bad{color:var(--bad-ink)}.progress3 li.bad span{background:var(--bad)}
.qcard{margin-top:24px}
.qcard legend{font-size:22px;font-weight:800;letter-spacing:-.015em;line-height:1.35;padding:0;margin-bottom:18px}
.qcard fieldset{border:none;padding:0;margin:0;display:flex;flex-direction:column;gap:10px}
.conf{display:flex;gap:8px;flex-wrap:wrap}
.conf button{min-height:44px;padding:0 18px;border-radius:999px;border:1px solid var(--line-3,#CBD5E1);background:var(--surface,#fff);font-size:15px;font-weight:600;cursor:pointer}
.conf button[aria-pressed=true]{background:var(--ink);border-color:var(--ink);color:var(--surface,#fff)}
.feedback{margin-top:20px;border-radius:var(--r-md);padding:24px 26px}
.feedback.ok{background:var(--ok-bg)}
.feedback.bad{background:var(--bad-bg)}
.feedback h3{font-size:20px;margin-bottom:8px}
.feedback.ok h3{color:var(--ok-ink)}.feedback.bad h3{color:var(--bad-ink)}
.tags3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;margin-top:12px}
.tags3 button{min-height:68px;padding:12px 14px;border-radius:14px;border:1px solid var(--line-3,#CBD5E1);background:var(--surface,#fff);text-align:left;cursor:pointer;display:flex;flex-direction:column;gap:2px}
.tags3 button b{font-weight:700;font-size:15px}
.tags3 button span{font-size:13px;color:var(--muted)}
.tags3 button[aria-pressed=true]{border:2px solid var(--brand);background:var(--bg-tint);padding:11px 13px}
.actions{display:flex;justify-content:space-between;align-items:center;gap:16px;margin-top:24px;flex-wrap:wrap}
.score{width:140px;height:140px;border-radius:999px;display:flex;flex-direction:column;align-items:center;justify-content:center;flex:0 0 auto}
.score b{font-size:46px;font-weight:800;line-height:1;letter-spacing:-.03em}
.score span{font-size:13px;font-weight:700}
.result-top{display:flex;gap:32px;align-items:center}
.rrow{display:grid;grid-template-columns:32px minmax(0,1fr) 120px 110px;gap:16px;padding:18px 0;border-top:1px solid var(--line-2);align-items:start}
.rrow .ic{width:28px;height:28px;border-radius:999px;display:flex;align-items:center;justify-content:center;color:#fff}
.rrow-head{display:grid;grid-template-columns:32px minmax(0,1fr) 120px 110px;gap:16px;font-size:13px;font-weight:700;color:var(--faint);padding-bottom:8px}
.cgrid{display:grid;grid-template-columns:1fr 1fr;gap:8px;font-size:14px}
.cgrid div{border-radius:12px;padding:12px}
.sched{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px}
.sched div{display:flex;flex-direction:column;gap:6px;font-size:14px}
.sched i{display:block;height:6px;border-radius:999px}

/* review */
.empty{padding:40px;text-align:center;color:var(--muted)}

/* ---------- responsive ---------- */
@media (max-width:1100px){
  .lesson-grid{grid-template-columns:minmax(0,1fr) 260px}
  .lesson-grid .toc-col{display:none}
  .grid-4{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media (max-width:860px){
  body{font-size:16px}
  .wrap{padding:0 16px}
  .menu-btn{display:inline-flex}
  .nav{display:none;position:absolute;top:76px;left:0;right:0;background:var(--surface,#fff);border-bottom:1px solid var(--line);flex-direction:column;padding:8px 16px 16px}
  .nav.open{display:flex}
  .nav-dd{flex-direction:column}
  .nav-dd-btn{cursor:default;pointer-events:none;justify-content:flex-start}
  .nav-dd-btn svg{display:none}
  .nav-dd-menu{display:flex;position:static;min-width:0;box-shadow:none;border:0;padding:0 0 4px 14px;border-left:2px solid var(--line-2);margin-left:14px;border-radius:0}
  .nav-dd-menu::before{display:none}
  .head-cta{display:none}
  .hero{padding:56px 0}
  .hero .wrap{grid-template-columns:1fr;gap:40px}
  .hero h1{font-size:40px}
  .section{padding-top:64px}
  .section-head h2,.dark-band h2,.cta-band h2{font-size:32px}
  .grid-4,.grid-3,.grid-2{grid-template-columns:1fr}
  .dark-band{grid-template-columns:1fr;padding:32px 24px;gap:32px}
  .cta-band{flex-direction:column;align-items:flex-start;padding:32px 24px}
  .site-foot .wrap{flex-direction:column;gap:16px}
  .page-head{padding:40px 0 28px}.page-head h1{font-size:38px}
  .search{min-width:0;width:100%}
  .learn-grid,.lesson-grid,.check-grid{grid-template-columns:1fr}
  .side,.lesson-side{position:static}
  .continue{grid-template-columns:1fr}
  .lrow{grid-template-columns:1fr auto;gap:8px 12px;padding:16px 18px}
  .lrow .ref{grid-column:1/-1}
  .lrow .pill{justify-self:start}
  .srow{grid-template-columns:1fr auto;gap:6px 12px;padding:14px 18px}
  .srow .ref{grid-column:1/-1}
  .group-head{padding:18px}
  .lesson-title h1{font-size:34px}
  .block{padding:22px 18px}
  .block h2{font-size:23px}
  .mapgrid,.qa,.tags3{grid-template-columns:1fr}
  .rule{grid-template-columns:1fr;gap:6px}
  .pager{grid-template-columns:1fr}
  .result-top{flex-direction:column;align-items:flex-start}
  .rrow,.rrow-head{grid-template-columns:28px minmax(0,1fr)}
  .rrow>:nth-child(3),.rrow>:nth-child(4){grid-column:2}
  .rrow-head>:nth-child(3),.rrow-head>:nth-child(4){display:none}
  .sched{grid-template-columns:1fr 1fr}
  .qcard legend{font-size:19px}
}
@media print{.site-head,.check-head,.site-foot,.toc-col,.lesson-side{display:none}}

/* study-notes notice + verbatim quotes */
.notice{display:flex;gap:12px;align-items:flex-start;background:var(--warn-bg,#FFF8E6);border:1px solid var(--warn-line,#F3DFA8);color:var(--warn-ink,#5C3D00);border-radius:16px;padding:14px 18px;font-size:14px;line-height:1.55;margin-top:20px}
.notice svg{flex:0 0 auto;margin-top:2px}
.notice a{color:var(--warn-ink,#5C3D00);font-weight:700}
.qlabel{font-size:12px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;color:var(--faint);margin-bottom:6px}
.actq{margin:0 0 8px;padding:12px 16px;border-left:3px solid var(--brand);background:var(--bg-soft);border-radius:0 12px 12px 0;font-family:Georgia,'Times New Roman',serif;font-size:15px;line-height:1.55;color:var(--ink)}
.actq .qc{font-family:'Plus Jakarta Sans',system-ui,sans-serif;font-size:12px;font-weight:800;color:var(--brand);margin-bottom:4px}
.actq p{margin:0 0 4px}
.actq .ql{font-weight:700}
.summ{font-size:14px;color:var(--ink-2);margin-top:8px}
.summ b{color:var(--ink)}
.rule .w{font-size:13px}
.block .actq p+p{margin-top:3px}

.science-strip{display:flex;justify-content:space-between;align-items:center;gap:24px;flex-wrap:wrap;background:var(--bg-tint);border-radius:var(--r-lg);padding:26px 30px}
.science-strip .tag{background:var(--surface,#fff)}

.exam-hero{padding:72px 0 64px}
.exam-groups{display:flex;flex-direction:column;gap:22px;margin-top:36px}
.exam-group .eyebrow{margin-bottom:10px}
.exam-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:12px}
.exam{display:flex;flex-direction:column;gap:8px;align-items:flex-start;background:var(--surface,#fff);border:1px solid var(--line);border-radius:16px;padding:16px 18px;color:var(--ink);text-decoration:none;min-height:96px}
.exam b{font-size:16px;line-height:1.3}
.exam[aria-disabled=true]{background:var(--glass-2,rgba(255,255,255,.6))}
.exam[aria-disabled=true] b{color:var(--muted)}
.exam.is-live{border:2px solid var(--brand);padding:15px 17px;box-shadow:var(--shadow)}
.exam.is-live:hover{background:var(--bg-soft,#FAFBFF);color:var(--ink)}
.study-card{display:grid;grid-template-columns:minmax(0,1.3fr) minmax(0,1fr) auto;gap:28px;align-items:center}
@media (max-width:860px){.study-card{grid-template-columns:1fr}.exam-hero{padding:48px 0 40px}}

.ctable{width:100%;border-collapse:collapse;font-family:'Plus Jakarta Sans',system-ui,sans-serif;font-size:13px;line-height:1.45;margin-top:6px;background:var(--surface,#fff)}
.ctable th,.ctable td{border:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
.ctable th{background:var(--bg-soft);font-weight:700}
.tnotes{font-family:'Plus Jakarta Sans',system-ui,sans-serif;font-size:12px;color:var(--muted);margin-top:8px}
.tnotes p{margin:0 0 3px}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.finds{display:flex;flex-direction:column;gap:12px}
.find{background:var(--surface,#fff);border-radius:14px;padding:16px;display:flex;flex-direction:column;gap:12px}
.find-q{display:flex;gap:12px;align-items:flex-start}
.find-q p{margin-top:2px}
.find-n{flex:none;width:26px;height:26px;border-radius:50%;background:var(--t-green);color:var(--t-green-ink);font-weight:800;font-size:13px;display:grid;place-items:center}
.find-f{display:flex;gap:8px;flex-wrap:wrap;padding-left:38px}
.find-f input{flex:1 1 140px;min-width:0;max-width:220px;border:1px solid var(--line);border-radius:10px;padding:8px 12px;font:inherit}
.find-f input:focus{outline:2px solid var(--brand);outline-offset:1px}
.find-r{padding-left:38px}
.find-r:empty{display:none}
.find-r .ok{color:var(--ok-ink);font-weight:700}
.find-r .no{color:var(--bad-ink);font-weight:700}
.find.is-done{outline:2px solid var(--ok)}
@media (max-width:560px){.find-f,.find-r{padding-left:0}}
.answers{display:flex;flex-direction:column;gap:12px}
.ans{background:var(--surface,#fff);border-radius:14px;padding:16px;display:flex;flex-direction:column;gap:10px}
.ans-q{display:flex;gap:12px;align-items:flex-start}
.ans-g,.ans-a{padding-left:38px}
.ans-a{border-left:3px solid var(--t-purple-ink);margin-left:38px;padding-left:12px}
.ans-a p{margin-top:4px}
@media (max-width:560px){.ans-g{padding-left:0}.ans-a{margin-left:0}}
.exit-card{display:flex;align-items:center;gap:16px;margin:8px 0 20px;padding:20px 24px;border:2px dashed var(--line-3,#C3CCDD);border-radius:var(--r-lg);background:var(--bg-soft);color:var(--ink-2);text-decoration:none;transition:border-color .15s,background .15s}
.exit-card:hover,.exit-card:focus-visible{border-color:var(--ink-2);background:var(--surface,#fff)}
.exit-ico{flex:none;width:42px;height:42px;border-radius:50%;background:var(--navy,#0F172A);color:#fff;display:grid;place-items:center}
.exit-txt{display:flex;flex-direction:column;gap:4px;min-width:0;flex:1}
.exit-txt .eyebrow{color:var(--faint)}
.exit-txt b{font-size:19px;color:var(--ink)}
.exit-txt .small{color:var(--muted)}
.exit-go{flex:none;font-weight:700;font-size:14px;color:var(--ink);border:1px solid var(--line);background:var(--surface,#fff);border-radius:999px;padding:8px 14px}
@media (max-width:560px){.exit-card{display:grid;grid-template-columns:auto 1fr;align-items:start;padding:18px;gap:12px 14px}.exit-go{grid-column:2;justify-self:start}}
#exams{scroll-margin-top:72px}

/* ---------- OBC Study home (Home – modern wireframe) ---------- */
.sample{display:flex;flex-direction:column;gap:16px;padding:28px}
.tool{display:flex;flex-direction:column;gap:12px;border:1px solid var(--line);border-radius:var(--r-lg);padding:28px;color:var(--ink);text-decoration:none;background:var(--surface,#fff)}
.tool:hover{border-color:var(--brand-line,#A5B4FC);box-shadow:var(--shadow);color:var(--ink)}
.tool h3{font-size:24px}
.tool p{font-size:15px;color:var(--muted);flex-grow:1}
.tool .go{font-weight:700;color:var(--brand);font-size:15px}
.tiers{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px;margin-top:40px;align-items:stretch}
.tier{border:1px solid var(--line);border-radius:var(--r-lg);padding:30px;display:flex;flex-direction:column;gap:18px;background:var(--surface,#fff)}
.tier.is-featured{border:2px solid var(--brand);background:var(--bg-tint);padding:29px}
.tier-head{display:flex;justify-content:space-between;align-items:center;gap:12px}
.tier-head h3{font-size:24px}
.price{font-size:44px;font-weight:800;letter-spacing:-.03em;line-height:1}
.tier .btn{margin-top:auto}
.ticks{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:10px;font-size:15px;color:var(--ink-2)}
.ticks li{display:flex;gap:10px;align-items:flex-start;line-height:1.5}
.ticks svg{flex:0 0 auto;color:var(--ok);margin-top:2px}
.plist{display:flex;flex-direction:column}
.plist>div{display:flex;justify-content:space-between;align-items:baseline;gap:12px;padding:12px 0;border-top:1px solid var(--line-2);font-weight:600;font-size:15px}
.plist>div:last-child{border-bottom:1px solid var(--line-2)}
.tier .note{background:var(--bg-soft);border-radius:var(--r-sm);padding:14px 16px;line-height:1.55;margin-top:auto}
.study-home{display:flex;flex-direction:column;gap:16px;padding:30px}
.faq>div{padding:20px 0;border-top:1px solid var(--line)}
.faq>div:last-child{border-bottom:1px solid var(--line)}
.faq p{margin-top:4px}
@media (max-width:860px){.tiers{grid-template-columns:1fr}.sample{padding:22px}#faq{grid-template-columns:1fr!important;gap:24px!important}}

/* ---------- learn.pline.studio hub ---------- */
.brand-sub{font-weight:600;color:var(--faint);margin-left:6px}
.brand-has-logo{display:inline-flex;align-items:baseline;gap:10px}
.brand-has-logo .brand-sub{margin-left:0;font-family:'Comfortaa','Plus Jakarta Sans',sans-serif;font-weight:300;font-size:25px;letter-spacing:.01em;line-height:1;position:relative;top:-.2px}
.brand-logo{display:block;color:var(--brand);height:36px;width:auto;stroke-width:1.6px;overflow:visible}
@media (max-width:600px){.brand-logo{height:28px;stroke-width:1.4px}.brand-has-logo .brand-sub{font-size:20px;top:-.45px}}
.hub-hero{padding:80px 0 64px}
.guides{display:flex;flex-direction:column;gap:20px}
.guide{display:grid;grid-template-columns:minmax(0,1.4fr) minmax(0,1fr);gap:40px;align-items:center;border:2px solid var(--brand);border-radius:28px;padding:40px;background:var(--surface,#fff);color:var(--ink);text-decoration:none;box-shadow:var(--shadow)}
.guide:hover{background:var(--bg-soft,#FAFBFF);color:var(--ink)}
.guide-main{display:flex;flex-direction:column;gap:14px}
.guide-main h2{font-size:44px}
.guide-facts{display:flex;flex-direction:column;gap:12px}
.guide-facts>div{display:flex;align-items:baseline;gap:14px;background:var(--bg-tint);border-radius:var(--r-md);padding:16px 20px}
.guide-facts b{font-size:28px;font-weight:800;letter-spacing:-.02em;color:var(--brand-ink);min-width:72px}
.guide-facts span{font-size:15px;color:var(--ink-2)}
@media (max-width:860px){.guide{grid-template-columns:1fr;padding:26px;gap:24px}.guide-main h2{font-size:34px}.hub-hero{padding:48px 0 32px}}
[hidden]{display:none!important}

/* ---------- legal pages (privacy, terms) ---------- */
.legal{max-width:760px}
.legal h2{font-size:22px;letter-spacing:-.01em;margin:36px 0 10px}
.legal p,.legal li{font-size:16px;color:var(--ink-2)}
.legal p+p{margin-top:10px}
.legal ul{margin:8px 0 0;padding-left:22px;display:flex;flex-direction:column;gap:6px}
.legal .lead{font-size:18px;color:var(--muted)}
.legal ul+p{margin-top:14px}

/* ---------- account (Google or email sign-in; the dialog styles itself in auth.js) ---------- */
.auth-slot{display:flex;align-items:center}
.auth-btn{gap:8px}
.auth-menu{position:relative}
.auth-me{display:flex;align-items:center;gap:8px;border:1px solid var(--line);background:var(--surface,#fff);border-radius:999px;padding:4px 12px 4px 4px;cursor:pointer;font:inherit;font-size:14px;font-weight:600;color:var(--ink)}
.auth-me:hover{background:var(--bg-soft)}
.auth-avatar{width:30px;height:30px;border-radius:999px;background:var(--brand-btn);color:#fff;display:inline-flex;align-items:center;justify-content:center;font-weight:800;font-size:14px}
.auth-pop{position:absolute;right:0;top:calc(100% + 8px);width:260px;background:var(--surface,#fff);border:1px solid var(--line);border-radius:16px;box-shadow:var(--shadow);padding:16px;z-index:50}
.site-head .wrap{gap:14px}
@media (max-width:860px){.auth-name{display:none}.auth-me{padding:4px}}
.gate-note{margin-top:4px;padding:12px 16px;border-radius:12px;background:var(--surface,#fff);border:1px solid var(--line);color:var(--brand-ink);font-size:15px;max-width:42em}
.link-btn{background:none;border:none;padding:0;font:inherit;font-weight:700;color:var(--brand);text-decoration:underline;text-underline-offset:2px;cursor:pointer}


/* medium widths: keep the main nav on one line */
@media (min-width:861px) and (max-width:1180px){.site-head .wrap{gap:16px}.nav{font-size:14px;gap:0}.nav a{padding:10px 8px;white-space:nowrap}.nav-dd-btn{padding:10px 8px}.head-cta{display:none}.auth-name{display:none}.auth-me{padding:4px}}

/* ---------- Practice exam (questions come from the server, 70 per attempt) ---------- */
.ex-wrap{padding-top:32px}
.ex-stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px;margin-bottom:24px}
.ex-stat{background:var(--surface,#fff);border:1px solid var(--line);border-radius:var(--r-md);padding:20px 22px;display:flex;flex-direction:column;gap:4px}
.ex-stat b{font-size:34px;font-weight:800;letter-spacing:-.03em;line-height:1.1;color:var(--brand-ink)}
.ex-stat span{font-size:14px;color:var(--muted)}
.ex-how h2{font-size:26px;margin-bottom:14px}
.ex-how ol{margin:0;padding-left:22px;display:flex;flex-direction:column;gap:8px;color:var(--ink-2);max-width:52em}
.ex-how h3{font-size:18px;margin:24px 0 10px}
.ex-leave{margin:0;padding-left:22px;display:flex;flex-direction:column;gap:8px;color:var(--ink-2);max-width:52em}
.ex-resume{margin-top:22px;padding:16px 18px;border-radius:var(--r-sm);background:var(--warn-bg);color:var(--warn-ink);display:flex;gap:12px;align-items:center;flex-wrap:wrap;font-size:15px}
.ex-pay{margin-top:22px;padding:16px 18px;border-radius:var(--r-sm);background:var(--brand-chip);color:var(--brand-ink);display:flex;gap:12px;align-items:center;flex-wrap:wrap;font-size:15px}
.ex-pay[hidden]{display:none}
.ex-modes{border:none;margin:24px 0 0;padding:0;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}
.ex-modes legend{font-size:18px;font-weight:800;letter-spacing:-.01em;margin-bottom:12px;padding:0}
.ex-mode{position:relative;display:flex;flex-direction:column;gap:6px;padding:16px 18px 16px 48px;border:1px solid var(--line);border-radius:var(--r-md);background:var(--surface,#fff);cursor:pointer}
.ex-mode:hover{border-color:var(--brand-line,#A5B4FC);background:var(--bg-soft,#FAFBFF)}
.ex-mode input{position:absolute;left:18px;top:19px;width:18px;height:18px;margin:0;accent-color:var(--brand)}
.ex-mode:has(input:checked){border:2px solid var(--brand);background:var(--bg-tint);padding:15px 17px 15px 47px}
.ex-mode:has(input:checked) input{left:17px;top:18px}
.ex-mode:has(input:focus-visible){outline:3px solid var(--brand);outline-offset:2px}
.ex-mode-t{font-weight:700;font-size:16px;line-height:1.35}
.ex-mode-d{font-size:14px;color:var(--muted);line-height:1.45}
@media (max-width:860px){.ex-modes{grid-template-columns:1fr}}
.ex-err{margin-top:14px;padding:12px 14px;border-radius:var(--r-sm);background:var(--bad-bg);color:var(--bad-ink);font-size:15px}
.ex-bar{position:sticky;top:76px;z-index:15;background:var(--glass,rgba(255,255,255,.97));backdrop-filter:blur(8px);border:1px solid var(--line);border-radius:var(--r-md);box-shadow:var(--shadow);margin:8px 0 20px;overflow:hidden}
.ex-bar-top{display:flex;align-items:center;gap:12px;flex-wrap:wrap;padding:12px 16px 4px}
.ex-bar-sub{display:flex;align-items:center;gap:12px;flex-wrap:wrap;padding:0 16px 10px;min-height:26px}
.ex-timer{font-variant-numeric:tabular-nums;font-weight:800;font-size:20px;letter-spacing:-.01em}
.ex-clock{display:inline-flex;align-items:baseline;gap:8px}
.ex-clock-l{font-size:13px;font-weight:600;color:var(--faint)}
.ex-clock.is-warn .ex-timer{color:#B45309}
.ex-clock.is-urgent .ex-timer{color:var(--bad-ink)}
.ex-saved{min-width:0}
.ex-bar-refs{display:flex;align-items:center;gap:10px 14px;flex-wrap:wrap;padding:10px 16px;background:var(--bg-tint);border-bottom:1px solid var(--line-2);border-radius:inherit;border-bottom-left-radius:0;border-bottom-right-radius:0}
.ex-refs-h{display:flex;flex-direction:column;gap:1px;margin-right:6px}
.ex-refs-l{font-size:13px;font-weight:700;color:var(--brand-ink)}
.ex-ref{gap:0}
.ex-ref-long{margin-right:.3em}
.ex-refs{display:inline-flex;gap:8px;flex-wrap:wrap}
.ex-ref{white-space:nowrap}
.ex-actions{display:flex;gap:8px;margin-left:auto;flex-wrap:wrap}
.ex-ext{margin-left:6px;font-size:.85em;opacity:.7}
@media (max-width:600px){.ex-ref-long{display:none}.ex-refs{flex-wrap:nowrap}.ex-bar .ex-ref.btn-sm{padding:0 10px}.ex-bar-refs{padding:8px 12px;gap:6px 10px}.ex-refs-h{width:100%}.ex-refs-n{display:none}}
.ex-note{margin:0 0 14px;padding:12px 16px;border-radius:12px;background:var(--bg-soft);font-size:15px}
.ex-prog{height:4px;background:var(--line-2)}.ex-prog i{display:block;height:100%;width:0;background:var(--brand-btn);transition:width .2s}
.ex-paper{display:flex;flex-direction:column;gap:16px}
.exq{margin:0;padding:24px 26px;scroll-margin-top:170px;min-width:0}
.exq legend{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}
.exq-head{display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.exq-num{width:34px;height:34px;border-radius:10px;background:var(--brand-chip);color:var(--brand-ink);display:inline-flex;align-items:center;justify-content:center;font-weight:800;font-size:15px;flex:0 0 auto}
.exq-topic{font-size:13px;font-weight:700;color:var(--faint);letter-spacing:.02em}
.exq-mark{margin-left:auto;min-height:34px;padding:0 14px;font-size:13px}
.exq-mark[aria-pressed=true]{background:var(--warn-bg);border-color:var(--warn,#E9C46A);color:var(--warn-ink)}
.exq-stem{font-size:18px;font-weight:600;line-height:1.5;margin:14px 0 14px;color:var(--ink)}
.exq-opts{display:flex;flex-direction:column;gap:8px}
.exq label.opt{cursor:pointer;position:relative}
.exq label.opt:hover{border-color:var(--brand-line,#A5B4FC);background:var(--bg-soft,#FAFBFF)}
.exq label.opt input{position:absolute;opacity:0;width:1px;height:1px}
.exq label.opt:has(input:focus-visible){outline:3px solid var(--brand);outline-offset:2px}
.exq.is-unsure{border-color:var(--warn,#E9C46A);box-shadow:0 0 0 2px var(--warn-bg)}
.exq-tag{display:none}
.exq.is-unsure .exq-tag-u{display:inline-flex}
.exq.is-blank .exq-tag-b{display:inline-flex}
.exq-ref{margin-top:14px;padding:12px 14px;border-radius:var(--r-sm);background:var(--bg-soft);font-size:14px;color:var(--ink-2)}
.ex-paper.is-done label.opt{cursor:default}.ex-paper.is-done label.opt:hover{border-color:var(--line);background:var(--surface,#fff)}
.ex-paper.is-done label.opt.is-right:hover{border-color:var(--ok);background:var(--ok-bg)}
.ex-paper.is-done label.opt.is-wrong:hover{border-color:var(--bad);background:var(--bad-bg)}
.exq.is-hit{border-left:5px solid var(--ok)}.exq.is-miss,.exq.is-blank{border-left:5px solid var(--bad)}
.ex-filter{display:flex;gap:8px;flex-wrap:wrap;margin:24px 0 16px}
.ex-result{margin-bottom:8px}
.ex-score{display:flex;align-items:baseline;gap:16px;flex-wrap:wrap}
.ex-score b{font-size:56px;font-weight:800;letter-spacing:-.04em;line-height:1}
.ex-score .pill{font-size:13px;padding:6px 14px}
.ex-facts{display:flex;gap:10px 28px;flex-wrap:wrap;margin-top:14px;color:var(--muted);font-size:15px}
.ex-facts b{color:var(--ink)}
.ex-topics{margin-top:28px}
.ex-topics h3{font-size:20px;margin-bottom:6px}
.ex-trow{display:grid;grid-template-columns:minmax(0,1.4fr) minmax(0,1fr) 64px;gap:16px;align-items:center;padding:10px 0;border-top:1px solid var(--line-2);font-size:15px}
.ex-trow.low .ex-tname{font-weight:700;color:var(--bad-ink)}
.ex-tbar{position:relative;height:10px;border-radius:999px;background:var(--line-2);overflow:visible}
.ex-tbar i{display:block;height:100%;border-radius:999px;background:var(--ok)}
.ex-trow.low .ex-tbar i{background:var(--bad)}
.ex-tbar:after{content:"";position:absolute;left:70%;top:-4px;bottom:-4px;width:2px;background:var(--ink);opacity:.55}
.ex-tn{text-align:right;font-variant-numeric:tabular-nums;color:var(--muted)}
.ex-focus{margin-top:18px;padding:14px 16px;border-radius:var(--r-sm);background:var(--bg-tint);color:var(--brand-ink);font-size:15px}
@media (max-width:860px){
  .ex-stats{grid-template-columns:repeat(2,minmax(0,1fr))}
  .ex-stat b{font-size:28px}
  .exq{padding:18px 16px;scroll-margin-top:200px}
  .exq-stem{font-size:17px}
  .ex-bar-top{gap:8px;padding:10px 12px 4px}.ex-bar-sub{padding:0 12px 8px}
  .ex-bar-top .head-spacer{display:none}
  .ex-actions{margin-left:0}
  .ex-bar .btn-sm{min-height:36px;padding:0 12px}
  .ex-trow{grid-template-columns:minmax(0,1fr) 56px;gap:4px 12px}
  .ex-tbar{grid-column:1/-1;grid-row:2}
  .ex-score b{font-size:44px}
}
/* one collapsible box for every disclaimer on a lesson page (compact_notice) */
details.notice-all{display:block}
details.notice-all>summary{display:flex;gap:12px;align-items:flex-start;cursor:pointer;list-style:none}
details.notice-all>summary::-webkit-details-marker{display:none}
details.notice-all>summary svg{flex:0 0 auto;margin-top:2px}
details.notice-all .notice-more{color:var(--brand);font-weight:700;white-space:nowrap}
details.notice-all .notice-more::after{content:" ▸"}
details.notice-all[open] .notice-more::after{content:" ▾"}
details.notice-all .notice-body{padding:8px 0 0 30px}
details.notice-all .notice-body p+p{margin-top:8px}
/* Recall before you read and Recall answers share one colour (lessons with answers_early) */
.block.tinted.t-purple.pair{background:var(--t-purple)}
.block.pair .block-k .n{background:var(--surface,#fff)}
.block.pair .field input{background:var(--surface,#fff)}

/* Seven nav items: keep them on one line by dropping the header CTA (Learn is in the nav) until there is room */
@media (min-width:1101px) and (max-width:1440px){.nav a{padding:10px 10px}.head-cta{display:none}}

/* Lessons list: study plan hero + self-paced band */
.plan-hero{background:var(--bg-tint);padding:48px 0 64px}
.plan-hero .wrap{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);gap:56px;align-items:center}
.plan-hero-copy{display:flex;flex-direction:column;gap:18px;align-items:flex-start}
.plan-hero h1{font-size:50px;letter-spacing:-.035em;max-width:13em}
.plan-hero .lead{max-width:34em}
.plan-feats{list-style:none;margin:2px 0 0;padding:0;display:flex;flex-direction:column;gap:10px;font-size:16px;line-height:1.5;color:var(--muted)}
.plan-feats li{position:relative;padding-left:32px}
.plan-feats li::before{content:"";position:absolute;left:0;top:2px;width:20px;height:20px;border-radius:50%;background:var(--brand-btn) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M6 12.5l4 4 8-9'/%3E%3C/svg%3E") center/13px no-repeat}
.plan-feats b{color:var(--ink)}
.plan-hero-cta{display:flex;align-items:center;gap:20px;flex-wrap:wrap;margin-top:6px}
.plan-alt{font-weight:700;color:var(--ink-2);text-decoration:none;border-bottom:2px solid var(--line);padding-bottom:2px}
.plan-alt:hover{color:var(--brand);border-color:var(--brand)}
.plan-demo{background:var(--surface,#fff);border:1px solid var(--line);border-radius:var(--r-lg);box-shadow:var(--shadow);padding:20px;display:flex;flex-direction:column;gap:8px}
.plan-demo-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:6px}
.plan-demo-head b{font-size:20px;letter-spacing:-.015em}
.plan-day{display:grid;grid-template-columns:64px minmax(0,1fr) auto;gap:12px;align-items:center;padding:10px 12px;border-radius:var(--r-sm);border:1px solid var(--line-2);background:var(--bg-soft)}
.plan-day.is-today{border-color:var(--brand);background:var(--surface,#fff);box-shadow:0 0 0 3px var(--brand-chip)}
.plan-day .d{font-size:13px;font-weight:800;color:var(--faint)}
.plan-day.is-today .d{color:var(--brand)}
.plan-day b{display:block;font-size:14.5px;line-height:1.35;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.plan-day div span{font-size:13px;color:var(--faint)}
.plan-day .tag{font-size:12px;font-weight:700;padding:3px 9px;border-radius:999px}
.tag.t-blue{background:var(--t-blue);color:var(--t-blue-ink)}.tag.t-green{background:var(--t-green);color:var(--t-green-ink)}
.tag.t-orange{background:var(--t-orange);color:var(--t-orange-ink)}.tag.t-purple{background:var(--t-purple);color:var(--t-purple-ink)}
.plan-demo-foot{display:flex;align-items:center;gap:12px;font-size:13px;color:var(--faint);margin-top:6px}
.plan-demo-foot .bar{flex:1}
.self-paced{border-bottom:1px solid var(--line);padding:40px 0 28px}
.self-paced .wrap{display:flex;flex-direction:column;gap:10px}
.self-paced h2{font-size:32px}
@media (max-width:980px){.plan-hero .wrap{grid-template-columns:1fr;gap:36px}.plan-hero h1{font-size:38px}}
@media (max-width:640px){.plan-hero{padding:32px 0 44px}.plan-hero h1{font-size:32px}.plan-demo{padding:14px}.plan-day{grid-template-columns:52px minmax(0,1fr) auto;gap:8px;padding:9px 10px}.self-paced h2{font-size:26px}}

/* Home: How it works + the science, merged */
.how-band{display:flex;flex-direction:column;gap:40px;align-items:stretch}
.how-head{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,1fr);gap:48px;align-items:end}
.how-steps{gap:14px}.how-band h2{font-size:38px}
.how-step{background:var(--navy-2);border-radius:18px;padding:22px;display:flex;flex-direction:column;gap:10px}
.how-num{width:36px;height:36px;border-radius:11px;background:white;color:#0F172A;display:grid;place-items:center;font-weight:800}
.how-step h3{font-size:20px;color:#fff;letter-spacing:-.01em}
.how-band .how-step p{font-size:15px;line-height:1.55;flex:1}
.how-tags{display:flex;flex-wrap:wrap;gap:6px;margin-top:4px}
.how-tags span{font-size:11.5px;font-weight:700;padding:3px 8px;white-space:nowrap;border-radius:999px;background:rgba(255,255,255,.07)}
@media (max-width:980px){.how-head{grid-template-columns:1fr;gap:16px}}

/* Practice exams landing (/obc/practice-exams/) */
.px-first{padding-top:64px}
.px-live{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(300px,1fr);background:var(--surface,#fff);border:2px solid var(--brand);border-radius:var(--r-lg);box-shadow:var(--shadow);overflow:hidden}
.px-live-main{padding:32px;display:flex;flex-direction:column;gap:14px}
.px-live h2{font-size:36px}
.px-tags{display:flex;gap:10px;align-items:center;flex-wrap:wrap}
.px-facts{margin:8px 0 0}
.px-facts .ex-stat{background:var(--bg-soft);border-color:var(--line-2);padding:16px 18px}
.px-facts .ex-stat b{font-size:28px}
.px-facts .ex-stat span{font-size:13px}
.px-you{background:var(--bg-tint);padding:32px;display:flex;flex-direction:column;gap:14px;border-left:1px solid var(--line)}
.px-you-body{display:flex;flex-direction:column;gap:10px}
.px-score{display:flex;align-items:baseline;gap:10px;flex-wrap:wrap}
.px-score b{font-size:40px;font-weight:800;letter-spacing:-.03em;line-height:1;color:var(--brand-ink)}
.px-rows{display:grid;grid-template-columns:auto 1fr;gap:4px 16px;font-size:14px;color:var(--muted)}
.px-rows dt{font-weight:600;color:var(--ink-2)}.px-rows dd{margin:0;text-align:right}
.px-you-go{display:flex;flex-direction:column;gap:10px;margin-top:auto}
.px-you-go .btn{width:100%}
.exam.is-next{border-style:dashed;border-color:var(--line-3,#CBD5E1)}
@media (max-width:980px){.px-live{grid-template-columns:1fr}.px-you{border-left:0;border-top:1px solid var(--line)}}
@media (max-width:860px){.px-first{padding-top:48px}.px-live-main,.px-you{padding:22px}.px-live h2{font-size:28px}}
.px-mine{display:flex;flex-direction:column;gap:20px}
.px-live.is-next{border:2px dashed var(--line-3,#CBD5E1);box-shadow:none}
.px-live.is-next .px-you{background:var(--bg-soft)}
.page-head + .section[hidden] + .section{padding-top:64px}
@media (max-width:860px){.page-head + .section[hidden] + .section{padding-top:48px}}

/* exam result: sent to Review */
.ex-sent{margin-top:20px;padding:16px 18px;border:1px solid var(--line);border-radius:var(--r-md);background:var(--bg-soft)}
.ex-sent h3{font-size:18px;margin-bottom:4px}
.ex-sent ul{margin:8px 0 12px;padding-left:20px;display:flex;flex-direction:column;gap:4px;font-size:15px}
/* Shop (/obc/shop/) — shop.js */
.sh-head{padding:40px 0 8px}
.sh-head h1{font-size:40px}
.sh-head p{margin-top:6px}
.sh-body{padding:24px 0 96px}
.sh-grid{display:grid;grid-template-columns:minmax(0,1fr) 340px;gap:40px;align-items:start}
.sh-list h2{font-size:22px;margin:8px 0 10px}
.sh-list h2:not(:first-child){margin-top:36px}
.sh-rows{list-style:none;margin:0;padding:0;border:1px solid var(--line);border-radius:var(--r-md);overflow:hidden;background:var(--surface,#fff)}
.sh-g{padding:8px 18px;background:var(--bg-soft);font-size:12px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--faint);border-top:1px solid var(--line)}
.sh-g:first-child{border-top:0}
.sh-row{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:12px 18px;border-top:1px solid var(--line-2);min-height:60px}
.sh-g+.sh-row{border-top:0}
.sh-row[aria-disabled=true] b{color:var(--muted);font-weight:600}
.sh-name{display:flex;flex-direction:column;gap:2px;min-width:0}
.sh-act{display:flex;align-items:center;gap:12px;flex:none}
.sh-p{font-weight:700}.sh-p:empty{display:none}
.sh-act .btn{min-width:84px}
.sh-cart{position:sticky;top:96px;background:var(--surface,#fff);border:1px solid var(--line);border-radius:var(--r-lg);padding:22px;box-shadow:var(--shadow);display:flex;flex-direction:column;gap:12px}
.sh-cart h2{font-size:22px}
.sh-cart [data-cart-body]{display:flex;flex-direction:column;gap:14px}
.sh-lines{list-style:none;margin:0;padding:0;display:flex;flex-direction:column}
.sh-lines li{padding:12px 0;border-top:1px solid var(--line-2);display:flex;flex-direction:column;gap:8px}
.sh-lines li:first-child{border-top:0;padding-top:0}
.sh-l-top{display:flex;justify-content:space-between;gap:10px;align-items:baseline}
.sh-l-top b{font-size:15px}
.sh-l-bot{display:flex;align-items:center;gap:10px}
.sh-l-amt{margin-left:auto}
.sh-step{display:inline-flex;align-items:center;border:1px solid var(--line-3,#CBD5E1);border-radius:10px;background:var(--surface,#fff);overflow:hidden}
.sh-step button{width:34px;height:36px;border:0;background:none;font:inherit;font-size:18px;font-weight:700;color:var(--ink);cursor:pointer}
.sh-step button:hover{background:var(--bg-soft)}
.sh-step input{width:44px;height:36px;border:0;border-left:1px solid var(--line);border-right:1px solid var(--line);text-align:center;font:inherit;font-size:15px;font-weight:700;color:var(--ink);-moz-appearance:textfield;appearance:textfield}
.sh-step input::-webkit-outer-spin-button,.sh-step input::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}
.sh-for{border:0;margin:0;padding:12px 0 0;border-top:1px solid var(--line-2);display:flex;flex-direction:column;gap:6px}
.sh-for legend{font-weight:700;padding:0;margin-bottom:6px}
.sh-for label{display:flex;gap:8px;align-items:center;font-size:14px;cursor:pointer}
.sh-for input{accent-color:var(--brand);width:16px;height:16px}
.sh-tot{display:flex;justify-content:space-between;align-items:baseline;padding-top:12px;border-top:1px solid var(--line-2);font-weight:700}
.sh-tot b{font-size:22px}
.sh-go{width:100%}
.sh-cart .acct-msg{font-size:14px;padding:10px 12px;border-radius:10px}.sh-cart .acct-msg:empty{display:none}
.sh-cart .acct-msg.bad{background:var(--bad-bg);color:var(--bad-ink)}
.sh-bar{display:none}
@media (max-width:980px){
  .sh-grid{grid-template-columns:1fr;gap:28px}
  .sh-cart{position:static;scroll-margin-top:90px}
  .sh-bar:not([hidden]){display:flex;position:fixed;left:12px;right:12px;bottom:12px;z-index:40;align-items:center;justify-content:space-between;gap:12px;padding:10px 10px 10px 18px;background:var(--ink);color:var(--surface,#fff);border-radius:999px;box-shadow:var(--shadow);font-weight:700;font-size:15px}
  .sh-body{padding-bottom:110px}
}
@media (max-width:560px){.sh-head h1{font-size:32px}.sh-row{padding:12px 14px}.sh-act .btn{min-width:72px}}
.sh-test{background:var(--warn-bg);color:var(--warn-ink);padding:8px 10px;border-radius:10px;margin:0}
.sh-t{list-style:none;border-top:1px solid var(--line)}
.sh-t:first-child{border-top:0}
.sh-t h3{font-size:16px;padding:14px 18px 2px;letter-spacing:-.01em}
.sh-items{list-style:none;margin:0;padding:0 0 6px}
.sh-items .sh-row{border-top:0;min-height:52px;padding:8px 18px 8px 34px}
.sh-items .sh-row b{font-size:15px}
@media (max-width:560px){.sh-t h3{padding:12px 14px 2px}.sh-items .sh-row{padding:8px 14px 8px 24px}}
.plist .pl-d{display:block;font-size:13px;font-weight:400;color:var(--faint);margin-top:2px}
.plist .pl-p{font-size:14px;font-weight:700;color:var(--ink);white-space:nowrap}
/* Background-only provisions (outside the exam syllabus): yellow, like the "Study notes" box */
.bg-tag{display:inline-block;align-self:flex-start;background:var(--warn-line,#F3DFA8);color:var(--warn-ink,#5C3D00);font-size:11px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;border-radius:999px;padding:3px 10px;margin-bottom:6px;white-space:nowrap}
.rule.rule-bg{background:var(--warn-bg,#FFF8E6);border-left:4px solid var(--warn-line,#F3DFA8)}
.bg-note{display:block;font-size:13px;color:var(--warn-ink,#5C3D00);margin-top:6px;line-height:1.4}
/* ---- paid lessons (lessonlock.js) ---- */
.pw{min-height:40vh}.pw-loading{padding:40px 0}
.pw-lock{display:flex;flex-direction:column;gap:12px;margin:24px 0;border-color:var(--brand);text-align:left}
.pw-lock h2{font-size:22px;margin:0}
.pw-ic{display:inline-flex;align-items:center;justify-content:center;width:44px;height:44px;border-radius:999px;background:var(--brand-chip);color:var(--brand)}
.pw-price{display:flex;align-items:baseline;gap:8px;flex-wrap:wrap}.pw-price b{font-size:26px}
.pw-lock .btn-row{display:flex;gap:10px;flex-wrap:wrap}

/* ---- light / dark screen mode (generated by theme.py) ---- */
:root{--surface:#FFFFFF;--line-3:#CBD5E1;--faint-2:#94A3B8;--chip-bg:#F1F5F9;--brand-btn:#3350E0;--brand-line:#C7D2FE;--ok-line:#BFEBD5;--bad-line:#F9D4D4;--warn:#E0A100;--warn-line:#F3DFA8;--glass:rgba(255,255,255,.96);--glass-2:rgba(255,255,255,.6);--brand-btn-h:#2238B8;color-scheme:light}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){--ink:#E6EAF2;--ink-2:#CBD5E1;--muted:#A7B3C6;--faint:#8B98AD;--faint-2:#6B788E;--line:#283246;--line-2:#212A3A;--line-3:#3A465C;--chip-bg:#232D3F;--bg:#0D1320;--bg-soft:#131A28;--bg-tint:#131B2C;--surface:#161E2E;--brand:#8EA2FF;--brand-dark:#B3C0FF;--brand-ink:#C9D3FF;--brand-chip:#222D57;--brand-btn:#4A63E8;--brand-line:#3A4A8C;--ok:#3CC488;--ok-bg:#11301F;--ok-ink:#8DE4B8;--ok-line:#1F5C3E;--bad:#F07171;--bad-bg:#3A1A1D;--bad-ink:#F6B3B3;--bad-line:#6B2C30;--warn:#E3A93B;--warn-bg:#33290F;--warn-ink:#F0CD7C;--warn-line:#6A5420;--t-blue:#17223D;--t-blue-ink:#A9C1FF;--t-green:#11301F;--t-green-ink:#8DE4B8;--t-purple:#241C42;--t-purple-ink:#C9B6FF;--t-orange:#36200F;--t-orange-ink:#FFB98F;--t-yellow:#302810;--t-yellow-ink:#F2D27A;--t-pink:#3A1828;--t-pink-ink:#F5A9C9;--navy:#1B2438;--navy-2:#28344F;--glass:rgba(13,19,32,.92);--glass-2:rgba(22,30,46,.6);--brand-btn-h:#3A52D6;--shadow:0 1px 2px rgba(0,0,0,.45),0 12px 32px rgba(0,0,0,.35);color-scheme:dark}}
:root[data-theme="dark"]{--ink:#E6EAF2;--ink-2:#CBD5E1;--muted:#A7B3C6;--faint:#8B98AD;--faint-2:#6B788E;--line:#283246;--line-2:#212A3A;--line-3:#3A465C;--chip-bg:#232D3F;--bg:#0D1320;--bg-soft:#131A28;--bg-tint:#131B2C;--surface:#161E2E;--brand:#8EA2FF;--brand-dark:#B3C0FF;--brand-ink:#C9D3FF;--brand-chip:#222D57;--brand-btn:#4A63E8;--brand-line:#3A4A8C;--ok:#3CC488;--ok-bg:#11301F;--ok-ink:#8DE4B8;--ok-line:#1F5C3E;--bad:#F07171;--bad-bg:#3A1A1D;--bad-ink:#F6B3B3;--bad-line:#6B2C30;--warn:#E3A93B;--warn-bg:#33290F;--warn-ink:#F0CD7C;--warn-line:#6A5420;--t-blue:#17223D;--t-blue-ink:#A9C1FF;--t-green:#11301F;--t-green-ink:#8DE4B8;--t-purple:#241C42;--t-purple-ink:#C9B6FF;--t-orange:#36200F;--t-orange-ink:#FFB98F;--t-yellow:#302810;--t-yellow-ink:#F2D27A;--t-pink:#3A1828;--t-pink-ink:#F5A9C9;--navy:#1B2438;--navy-2:#28344F;--glass:rgba(13,19,32,.92);--glass-2:rgba(22,30,46,.6);--brand-btn-h:#3A52D6;--shadow:0 1px 2px rgba(0,0,0,.45),0 12px 32px rgba(0,0,0,.35);color-scheme:dark}
.theme-btn{display:inline-flex;align-items:center;justify-content:center;width:40px;height:40px;border-radius:999px;border:1px solid var(--line);background:var(--surface);color:var(--ink-2);cursor:pointer;flex:none}
.theme-btn:hover{border-color:var(--line-3);color:var(--ink)}
.theme-btn svg{width:18px;height:18px}
:root[data-theme="dark"] img:not([src$=".svg"]){filter:brightness(.92)}