:root{
  --brand:#5b5bf6; --brand-ink:#fff; --bg:#f7f7fb; --surface:#fff; --surface-2:#f1f1f7; --ink:#17172a; --ink-2:#4b4b63; --muted:#7a7a92;
  --line:#e4e4ee; --ok:#139a5b; --ok-bg:#e8f8ef; --warn:#b7791f; --warn-bg:#fff6e0; --bad:#d23a3a; --bad-bg:#fdeeee;
  --radius:14px; --shadow:0 1px 2px rgba(20,20,50,.05),0 8px 24px rgba(20,20,50,.06);
  --font:ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  --read:"Iowan Old Style","Charter","Georgia",serif;
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){--bg:#0f0f19;--surface:#171726;--surface-2:#1f1f31;--ink:#ececf6;--ink-2:#b7b7cc;--muted:#8a8aa3;--line:#2b2b40;
    --ok-bg:#0f2c1f;--warn-bg:#2d2412;--bad-bg:#321616;--shadow:0 1px 2px rgba(0,0,0,.3),0 8px 24px rgba(0,0,0,.25)}
}
:root[data-theme="dark"]{--bg:#0f0f19;--surface:#171726;--surface-2:#1f1f31;--ink:#ececf6;--ink-2:#b7b7cc;--muted:#8a8aa3;--line:#2b2b40;--ok-bg:#0f2c1f;--warn-bg:#2d2412;--bad-bg:#321616}
*{box-sizing:border-box}
html,body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.55 var(--font);-webkit-font-smoothing:antialiased}
a{color:var(--brand)}
h1,h2,h3,h4{line-height:1.2;margin:0 0 .5em;letter-spacing:-.01em}
h1{font-size:clamp(26px,4vw,40px)} h2{font-size:22px} h3{font-size:17px}
p{margin:0 0 1em}
.muted{color:var(--muted)} .small{font-size:13px} .center{text-align:center}
.app{max-width:1200px;margin:0 auto;padding:24px 16px 80px}
.topbar{position:sticky;top:0;z-index:20;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:12px 20px;background:color-mix(in srgb,var(--surface) 88%,transparent);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.logo{display:flex;align-items:center;gap:10px;font-weight:700;color:var(--ink);text-decoration:none;font-size:16px}
.logo-mark{display:grid;place-items:center;width:30px;height:30px;border-radius:9px;background:var(--brand);color:var(--brand-ink);font-weight:800}
nav{display:flex;align-items:center;gap:6px;flex-wrap:wrap}
nav a{color:var(--ink-2);text-decoration:none;padding:7px 10px;border-radius:8px;font-weight:500}
nav a:hover,nav a.active{background:var(--surface-2);color:var(--ink)}
.credit-pill{font-size:12px;font-weight:600;background:var(--surface-2);border:1px solid var(--line);padding:4px 10px;border-radius:99px;color:var(--ink-2)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:1px solid transparent;border-radius:10px;padding:10px 16px;font:600 14px var(--font);cursor:pointer;text-decoration:none;background:var(--brand);color:var(--brand-ink);transition:transform .05s,filter .15s;white-space:nowrap}
.btn:hover{filter:brightness(1.08)} .btn:active{transform:translateY(1px)} .btn:disabled{opacity:.5;cursor:not-allowed;filter:none}
.btn.ghost{background:transparent;color:var(--ink);border-color:var(--line)} .btn.ghost:hover{background:var(--surface-2)}
.btn.danger{background:transparent;color:var(--bad);border-color:color-mix(in srgb,var(--bad) 40%,transparent)}
.btn.sm{padding:6px 11px;font-size:13px;border-radius:8px} .btn.lg{padding:14px 22px;font-size:16px;border-radius:12px}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.grid{display:grid;gap:16px} .g2{grid-template-columns:repeat(auto-fit,minmax(280px,1fr))} .g3{grid-template-columns:repeat(auto-fit,minmax(240px,1fr))} .g4{grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}
.row{display:flex;gap:10px;align-items:center;flex-wrap:wrap} .between{justify-content:space-between} .grow{flex:1}
label{display:block;font-weight:600;font-size:13px;margin:0 0 6px;color:var(--ink-2)}
input,select,textarea{width:100%;font:15px var(--font);color:var(--ink);background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:10px 12px;outline:none}
input:focus,select:focus,textarea:focus{border-color:var(--brand);box-shadow:0 0 0 3px color-mix(in srgb,var(--brand) 18%,transparent)}
textarea{min-height:90px;resize:vertical;line-height:1.5}
.field{margin-bottom:16px} .hint{font-size:12px;color:var(--muted);margin-top:4px}
.auth{max-width:420px;margin:40px auto}
.badge{display:inline-block;font-size:11px;font-weight:700;letter-spacing:.02em;text-transform:uppercase;padding:3px 8px;border-radius:99px;background:var(--surface-2);color:var(--ink-2)}
.badge.ok{background:var(--ok-bg);color:var(--ok)} .badge.warn{background:var(--warn-bg);color:var(--warn)} .badge.bad{background:var(--bad-bg);color:var(--bad)} .badge.brand{background:color-mix(in srgb,var(--brand) 14%,transparent);color:var(--brand)}
.alert{padding:12px 14px;border-radius:10px;background:var(--warn-bg);color:var(--ink);border:1px solid color-mix(in srgb,var(--warn) 30%,transparent);margin-bottom:16px;font-size:14px}
.alert.bad{background:var(--bad-bg);border-color:color-mix(in srgb,var(--bad) 30%,transparent)} .alert.ok{background:var(--ok-bg);border-color:color-mix(in srgb,var(--ok) 30%,transparent)}
.toast{position:fixed;bottom:20px;left:50%;transform:translateX(-50%) translateY(20px);background:var(--ink);color:var(--bg);padding:11px 16px;border-radius:10px;font-weight:600;opacity:0;pointer-events:none;transition:.2s;z-index:100;max-width:calc(100% - 32px)}
.toast.show{opacity:1;transform:translateX(-50%)}
.spinner{width:16px;height:16px;border:2px solid currentColor;border-right-color:transparent;border-radius:50%;animation:spin .8s linear infinite;display:inline-block;vertical-align:-3px}
@keyframes spin{to{transform:rotate(360deg)}}
.progress{height:8px;background:var(--surface-2);border-radius:99px;overflow:hidden} .progress>div{height:100%;background:var(--brand);border-radius:99px;transition:width .4s}
table.t{width:100%;border-collapse:collapse;font-size:14px} .t th,.t td{text-align:left;padding:9px 10px;border-bottom:1px solid var(--line);vertical-align:top} .t th{font-size:12px;color:var(--muted);text-transform:uppercase;letter-spacing:.03em}
.tabs{display:flex;gap:4px;border-bottom:1px solid var(--line);margin-bottom:20px;overflow-x:auto} .tabs a{padding:10px 14px;color:var(--ink-2);text-decoration:none;border-bottom:2px solid transparent;font-weight:600;white-space:nowrap} .tabs a.active{color:var(--brand);border-color:var(--brand)}
/* landing */
.hero{text-align:center;padding:56px 0 36px} .hero h1{font-size:clamp(32px,5.5vw,56px);max-width:860px;margin:0 auto 16px;letter-spacing:-.02em}
.hero p.lead{font-size:clamp(16px,2vw,20px);color:var(--ink-2);max-width:680px;margin:0 auto 26px}
.eyebrow{display:inline-block;font-weight:700;font-size:13px;color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,transparent);padding:6px 12px;border-radius:99px;margin-bottom:18px}
.feature h3{display:flex;gap:10px;align-items:center} .feature .ico{width:34px;height:34px;display:grid;place-items:center;border-radius:10px;background:color-mix(in srgb,var(--brand) 12%,transparent);color:var(--brand);font-size:17px;flex:none}
.section{margin:64px 0} .section>h2{text-align:center;font-size:clamp(24px,3vw,32px)} .section>p.sub{text-align:center;color:var(--ink-2);max-width:620px;margin:0 auto 28px}
.plan{display:flex;flex-direction:column} .plan.featured{border:2px solid var(--brand)} .plan .price{font-size:30px;font-weight:800;margin:6px 0} .plan ul{padding-left:18px;margin:12px 0 20px;flex:1} .plan li{margin:5px 0}
.compare td:not(:first-child),.compare th:not(:first-child){text-align:center}
.steps{counter-reset:s} .steps .card{position:relative;padding-top:30px} .steps .card::before{counter-increment:s;content:counter(s);position:absolute;top:-14px;left:22px;width:30px;height:30px;border-radius:50%;background:var(--brand);color:#fff;display:grid;place-items:center;font-weight:800}
/* course list */
.course-card{display:flex;flex-direction:column;gap:8px;text-decoration:none;color:inherit;transition:border-color .15s} .course-card:hover{border-color:var(--brand)}
.course-card h3{margin:0}
/* wizard */
.chips{display:flex;gap:8px;flex-wrap:wrap} .chip{border:1px solid var(--line);background:var(--surface);border-radius:99px;padding:7px 13px;cursor:pointer;font-weight:600;font-size:13px;color:var(--ink-2)} .chip.on{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,transparent);color:var(--brand)}
.drop{border:2px dashed var(--line);border-radius:12px;padding:22px;text-align:center;color:var(--muted);cursor:pointer} .drop.over{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 6%,transparent)}
.src-list{list-style:none;padding:0;margin:10px 0 0} .src-list li{display:flex;justify-content:space-between;align-items:center;gap:8px;padding:8px 10px;border:1px solid var(--line);border-radius:8px;margin-bottom:6px;font-size:14px;background:var(--surface-2)}
/* outline editor */
.mod{border:1px solid var(--line);border-radius:12px;padding:14px;margin-bottom:14px;background:var(--surface)}
.lesson-row{display:grid;grid-template-columns:1fr auto;gap:8px;padding:10px;border-radius:10px;background:var(--surface-2);margin-top:8px}
.lesson-row textarea{min-height:54px;font-size:13px}
.icon-btn{border:0;background:transparent;color:var(--muted);cursor:pointer;font-size:16px;padding:4px 6px;border-radius:6px} .icon-btn:hover{background:var(--line);color:var(--ink)}
/* viewer */
.viewer{display:grid;grid-template-columns:300px 1fr;gap:24px;align-items:start}
.sidebar{position:sticky;top:76px;max-height:calc(100vh - 96px);overflow:auto;padding:16px}
.sidebar .m{font-size:12px;font-weight:700;color:var(--muted);text-transform:uppercase;letter-spacing:.04em;margin:14px 0 6px}
.sidebar a.l{display:flex;gap:8px;align-items:flex-start;padding:7px 8px;border-radius:8px;color:var(--ink);text-decoration:none;font-size:14px} .sidebar a.l:hover{background:var(--surface-2)} .sidebar a.l.cur{background:color-mix(in srgb,var(--brand) 12%,transparent);color:var(--brand);font-weight:600}
.dot{width:18px;height:18px;flex:none;border-radius:50%;border:2px solid var(--line);margin-top:1px;display:grid;place-items:center;font-size:10px;color:#fff} .dot.done{background:var(--ok);border-color:var(--ok)} .dot.fail{background:var(--bad);border-color:var(--bad)} .dot.gen{border-color:var(--brand);border-right-color:transparent;animation:spin 1s linear infinite}
.lesson{padding:34px clamp(18px,4vw,48px)}
.prose{font:18px/1.75 var(--read);color:var(--ink)} .prose h2{font:700 23px/1.3 var(--font);margin:1.6em 0 .5em} .prose h3{font:700 18px/1.3 var(--font);margin:1.3em 0 .4em}
.prose ul,.prose ol{padding-left:1.4em} .prose li{margin:.3em 0} .prose code{font:14px ui-monospace,Menlo,monospace;background:var(--surface-2);padding:2px 5px;border-radius:5px}
.prose pre{background:#14142b;color:#f0f0ff;padding:16px;border-radius:10px;overflow:auto} .prose pre code{background:none;color:inherit;padding:0}
.prose table{border-collapse:collapse;width:100%;font:15px var(--font);margin:1em 0;display:block;overflow-x:auto} .prose th,.prose td{border:1px solid var(--line);padding:8px 10px} .prose th{background:var(--surface-2)}
.prose blockquote{border-left:4px solid var(--brand);margin:1em 0;padding:.2em 1em;color:var(--ink-2)}
sup.cite{font:700 11px var(--font);color:var(--brand);cursor:help}
.box{border-radius:12px;padding:14px 18px;margin:18px 0;font-size:15px} .box.obj{background:color-mix(in srgb,var(--brand) 8%,transparent)} .box.kp{background:var(--warn-bg)} .box ul{margin:.4em 0 0;padding-left:1.2em}
.quiz .q{border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin:12px 0;background:var(--surface)}
.quiz .opt{display:block;padding:9px 12px;border:1px solid var(--line);border-radius:9px;margin:7px 0;cursor:pointer;font-size:15px} .quiz .opt:hover{border-color:var(--brand)}
.quiz .opt.ok{border-color:var(--ok);background:var(--ok-bg)} .quiz .opt.bad{border-color:var(--bad);background:var(--bad-bg)} .quiz .fb{font-size:14px;color:var(--ink-2);margin-top:6px}
.cites{font-size:13px;color:var(--ink-2)} .cites li{margin:6px 0} .cites .snip{color:var(--muted);font-style:italic}
.toolbar{display:flex;gap:8px;flex-wrap:wrap;align-items:center;justify-content:space-between;margin-bottom:18px}
.menu{position:relative;display:inline-block} .menu-list{position:absolute;right:0;top:calc(100% + 6px);min-width:240px;background:var(--surface);border:1px solid var(--line);border-radius:12px;box-shadow:var(--shadow);padding:6px;z-index:30;display:none} .menu.open .menu-list{display:block}
.menu-list button{display:flex;width:100%;justify-content:space-between;gap:8px;text-align:left;background:none;border:0;padding:9px 10px;border-radius:8px;font:500 14px var(--font);color:var(--ink);cursor:pointer} .menu-list button:hover{background:var(--surface-2)} .menu-list button:disabled{color:var(--muted);cursor:not-allowed}
/* chat drawer */
.drawer{position:fixed;right:16px;bottom:16px;width:min(400px,calc(100vw - 32px));height:min(560px,calc(100vh - 100px));display:flex;flex-direction:column;z-index:40;padding:0;overflow:hidden}
.drawer header{display:flex;justify-content:space-between;align-items:center;padding:12px 16px;border-bottom:1px solid var(--line);font-weight:700}
.msgs{flex:1;overflow:auto;padding:14px;display:flex;flex-direction:column;gap:10px} .msg{padding:10px 13px;border-radius:12px;max-width:88%;font-size:14px;white-space:pre-wrap} .msg.user{align-self:flex-end;background:var(--brand);color:#fff} .msg.assistant{background:var(--surface-2)}
.drawer form{display:flex;gap:8px;padding:12px;border-top:1px solid var(--line)} .drawer input{flex:1}
.fab{position:fixed;right:20px;bottom:20px;z-index:35;border-radius:99px;box-shadow:var(--shadow)}
.modal-bg{position:fixed;inset:0;background:rgba(10,10,25,.45);display:grid;place-items:center;z-index:60;padding:16px} .modal{max-width:560px;width:100%;max-height:90vh;overflow:auto}
.kpi{font-size:28px;font-weight:800} .kpi-label{font-size:12px;color:var(--muted);text-transform:uppercase;letter-spacing:.04em;font-weight:700}
footer.site{border-top:1px solid var(--line);margin-top:60px;padding:24px 0;color:var(--muted);font-size:13px;text-align:center}
@media (max-width:860px){.viewer{grid-template-columns:1fr}.sidebar{position:static;max-height:none}.lesson{padding:22px 16px}.prose{font-size:17px}nav a.hide-sm{display:none}}
.lesson>h1{font-size:clamp(24px,3vw,32px)}
.logo span{white-space:nowrap}
@media (max-width:560px){.topbar{padding:10px 12px}.logo{font-size:15px}#brand-name{max-width:120px;overflow:hidden;text-overflow:ellipsis}nav{gap:2px;flex-wrap:nowrap}nav a{padding:6px 7px}.credit-pill{display:none}}