/* FinAcademy design system — light/dark, derived from the validated catalog palette */
:root{
  color-scheme: light;
  --surface:#fcfcfb; --page:#f9f9f7; --ink:#0b0b0b; --ink2:#52514e; --muted:#898781;
  --grid:#e1e0d9; --baseline:#c3c2b7; --ring:rgba(11,11,11,.10);
  --s1:#2a78d6; --s2:#eb6834; --s3:#1baf7a; --s4:#eda100; --s5:#e87ba4; --s6:#008300; --s7:#4a3aa7; --s8:#e34948;
  --good:#0ca30c; --goodtext:#006300; --warn:#fab219; --crit:#d03b3b;
  --accent:var(--s1);
}
@media (prefers-color-scheme: dark){
 :root:not([data-theme="light"]){
  color-scheme: dark;
  --surface:#1a1a19; --page:#0d0d0d; --ink:#ffffff; --ink2:#c3c2b7; --muted:#898781;
  --grid:#2c2c2a; --baseline:#383835; --ring:rgba(255,255,255,.10);
  --s1:#3987e5; --s2:#d95926; --s3:#199e70; --s4:#c98500; --s5:#d55181; --s6:#008300; --s7:#9085e9; --s8:#e66767;
  --good:#0ca30c; --goodtext:#0ca30c;
 }
}
:root[data-theme="dark"]{
  color-scheme: dark;
  --surface:#1a1a19; --page:#0d0d0d; --ink:#ffffff; --ink2:#c3c2b7; --muted:#898781;
  --grid:#2c2c2a; --baseline:#383835; --ring:rgba(255,255,255,.10);
  --s1:#3987e5; --s2:#d95926; --s3:#199e70; --s4:#c98500; --s5:#d55181; --s6:#008300; --s7:#9085e9; --s8:#e66767;
  --good:#0ca30c; --goodtext:#0ca30c;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--page);color:var(--ink);
  font:16px/1.6 system-ui,-apple-system,"Segoe UI",sans-serif;}
.wrap{max-width:1100px;margin:0 auto;padding:0 24px}

/* ---------- chrome ---------- */
.topnav{position:sticky;top:0;z-index:50;background:color-mix(in srgb, var(--page) 88%, transparent);
  backdrop-filter:blur(8px);border-bottom:1px solid var(--grid)}
.topnav .in{max-width:1100px;margin:0 auto;padding:10px 24px;display:flex;align-items:center;gap:14px}
.brand{font-weight:700;font-size:17px;text-decoration:none;color:var(--ink);letter-spacing:.01em}
.brand span{color:var(--accent)}
.topnav a.nl{color:var(--ink2);text-decoration:none;font-size:13.5px;padding:4px 2px;white-space:nowrap}
.topnav .pill{white-space:nowrap}
.topnav a.nl:hover{color:var(--ink)}
.topnav .right{margin-left:auto;display:flex;align-items:center;gap:10px}
.pill{font-size:12.5px;border:1px solid var(--ring);background:var(--surface);border-radius:14px;padding:3px 10px;color:var(--ink2);display:inline-block}
.theme-btn{border:1px solid var(--ring);background:var(--surface);color:var(--ink2);border-radius:8px;
  padding:5px 10px;cursor:pointer;font:inherit;font-size:13px}
.crumbs{font-size:13.5px;color:var(--muted);margin:22px 0 6px}
.crumbs a{color:var(--ink2);text-decoration:none}
.crumbs a:hover{text-decoration:underline}
footer.site{margin-top:70px;border-top:1px solid var(--grid);padding:26px 0 50px;color:var(--muted);font-size:13.5px}

/* ---------- typography ---------- */
h1{font-size:30px;line-height:1.2;margin:8px 0 10px;letter-spacing:-.01em}
h2{font-size:22px;margin:40px 0 10px}
h3{font-size:17.5px;margin:26px 0 8px}
.lead{font-size:17.5px;color:var(--ink2);max-width:760px}
.prose{max-width:780px}
.prose p{margin:12px 0}
.prose li{margin:6px 0}
.eyebrow{font-size:12.5px;font-weight:650;letter-spacing:.09em;text-transform:uppercase;color:var(--accent);margin:26px 0 0}
.katex-display{overflow-x:auto;overflow-y:hidden;padding:4px 0}

/* ---------- cards & grids ---------- */
.grid{display:grid;gap:14px}
.grid.c3{grid-template-columns:repeat(auto-fill,minmax(300px,1fr))}
.grid.c2{grid-template-columns:repeat(auto-fill,minmax(380px,1fr))}
.card{background:var(--surface);border:1px solid var(--ring);border-radius:14px;padding:18px 20px;position:relative}
.card.top{border-top:4px solid var(--accent)}
.card h3{margin:0 0 6px}
.card p{color:var(--ink2);font-size:14px;margin:6px 0}
.card a.cover{position:absolute;inset:0;border-radius:14px}
.card .meta{font-size:12.5px;color:var(--muted);margin-top:10px}
.skill{font-size:11px;font-weight:650;letter-spacing:.05em;text-transform:uppercase;color:var(--ink2);
  background:var(--page);border:1px solid var(--ring);border-radius:12px;padding:2px 9px}
.badge-soon{font-size:11px;font-weight:600;color:var(--muted);border:1px dashed var(--baseline);border-radius:12px;padding:2px 9px}
.dot{display:inline-block;width:11px;height:11px;border-radius:3px;vertical-align:-1px}

/* ---------- theory boxes ---------- */
.box{border:1px solid var(--ring);border-left:4px solid var(--accent);background:var(--surface);
  border-radius:10px;padding:14px 18px;margin:18px 0;max-width:780px}
.box .tag{font-size:12px;font-weight:700;letter-spacing:.07em;text-transform:uppercase;margin:0 0 6px;color:var(--accent)}
.box.def{border-left-color:var(--s1)}   .box.def .tag{color:var(--s1)}
.box.ex{border-left-color:var(--s3)}    .box.ex .tag{color:var(--s3)}
.box.warn{border-left-color:var(--warn)}.box.warn .tag{color:#8a6200}
:root[data-theme="dark"] .box.warn .tag{color:var(--warn)}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]) .box.warn .tag{color:var(--warn)}}
.box.note{border-left-color:var(--baseline)} .box.note .tag{color:var(--muted)}
.formula-card{background:var(--surface);border:1px solid var(--ring);border-radius:12px;padding:10px 18px;margin:16px 0;max-width:780px}
.symbols{font-size:13.5px;color:var(--ink2);border-top:1px dashed var(--grid);margin-top:8px;padding-top:8px}
.symbols b{font-weight:600;color:var(--ink)}
details.sol{margin-top:10px;font-size:14.5px}
details.sol summary{cursor:pointer;color:var(--accent);font-weight:600;font-size:13.5px}
details.sol .inner{border-left:3px solid var(--grid);padding:6px 0 2px 14px;margin-top:8px}

/* ---------- widgets ---------- */
.widget{background:var(--surface);border:1px solid var(--ring);border-radius:14px;padding:18px 20px;margin:22px 0;max-width:780px;box-sizing:border-box}
.widget h3{margin-top:0}
.widget .sub{color:var(--ink2);font-size:13.5px;margin:2px 0 14px}
.ctrls{display:flex;gap:18px;flex-wrap:wrap;margin-bottom:12px}
.ctrl{display:flex;flex-direction:column;gap:4px;font-size:13px;color:var(--ink2);min-width:150px}
.ctrl .val{color:var(--ink);font-weight:600;font-variant-numeric:tabular-nums}
.ctrl input[type=range]{width:170px;accent-color:var(--accent)}
.ctrl select,.ctrl input[type=number]{padding:7px 9px;border:1px solid var(--ring);border-radius:8px;
  background:var(--page);color:var(--ink);font:inherit;font-size:14px;width:170px}
.readouts{display:flex;gap:12px;flex-wrap:wrap;margin:10px 0 4px}
.readout{background:var(--page);border:1px solid var(--ring);border-radius:10px;padding:8px 14px;min-width:130px}
.readout .k{font-size:12px;color:var(--muted)}
.readout .v{font-size:18px;font-weight:650;font-variant-numeric:tabular-nums}
.chart{width:100%;height:auto;display:block;margin-top:6px}
.chart text{font:12px system-ui,-apple-system,"Segoe UI",sans-serif;fill:var(--muted)}
.chart .axis{stroke:var(--baseline)} .chart .gridln{stroke:var(--grid)}
.legend{display:flex;gap:16px;flex-wrap:wrap;font-size:13px;color:var(--ink2);margin-top:8px}
.legend .it{display:flex;align-items:center;gap:6px}
.legend .sw{width:12px;height:12px;border-radius:3px}
.tbl-scroll{overflow:auto;max-height:340px;border:1px solid var(--grid);border-radius:10px;margin-top:12px}
table.data{border-collapse:collapse;width:100%;font-size:13px;min-width:560px}
table.data th{position:sticky;top:0;background:var(--surface);text-align:right;padding:8px 10px;color:var(--ink2);
  border-bottom:1px solid var(--baseline);font-weight:600}
table.data td{text-align:right;padding:6px 10px;border-top:1px solid var(--grid);font-variant-numeric:tabular-nums}
table.data th:first-child,table.data td:first-child{text-align:left}

/* ---------- exercises ---------- */
.exercise{background:var(--surface);border:1px solid var(--ring);border-radius:12px;padding:16px 18px;margin:14px 0;max-width:780px}
.exercise .qhead{display:flex;align-items:center;gap:10px;margin-bottom:6px}
.exercise .qnum{font-size:12px;font-weight:700;color:var(--accent);letter-spacing:.05em;text-transform:uppercase}
.exercise .status{margin-left:auto;font-size:12.5px;font-weight:600}
.exercise .status.ok{color:var(--goodtext)}
.exercise .status.bad{color:var(--crit)}
.answer-row{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin-top:10px}
.answer-row input[type=text]{padding:8px 12px;border:1px solid var(--ring);border-radius:8px;background:var(--page);
  color:var(--ink);font:inherit;font-size:15px;width:180px;font-variant-numeric:tabular-nums}
.answer-row .unit{color:var(--muted);font-size:14px}
.btn{border:1px solid var(--ring);background:var(--accent);color:#fff;border-radius:8px;padding:8px 16px;
  cursor:pointer;font:inherit;font-size:14px;font-weight:600}
.btn.ghost{background:var(--surface);color:var(--ink2)}
.btn:disabled{opacity:.55;cursor:default}
.mc{display:flex;flex-direction:column;gap:8px;margin-top:10px}
.mc label{display:flex;gap:10px;align-items:flex-start;padding:9px 12px;border:1px solid var(--ring);
  border-radius:9px;cursor:pointer;background:var(--page);font-size:14.5px}
.mc label:has(input:checked){border-color:var(--accent);outline:1px solid var(--accent)}
.feedback{margin-top:10px;font-size:14px;display:none}
.feedback.show{display:block}

/* ---------- progress ---------- */
.progress-panel{background:var(--surface);border:1px solid var(--ring);border-radius:14px;padding:18px 20px;margin:20px 0}
.pbar{height:10px;background:var(--page);border:1px solid var(--grid);border-radius:6px;overflow:hidden}
.pbar>div{height:100%;background:var(--accent);border-radius:6px 0 0 6px;transition:width .3s}
.plabel{display:flex;justify-content:space-between;font-size:13px;color:var(--ink2);margin-top:6px}
.lesson-list{list-style:none;margin:14px 0;padding:0;max-width:780px}
.lesson-list li{border:1px solid var(--ring);background:var(--surface);border-radius:12px;margin:10px 0;position:relative}
.lesson-list a{display:flex;align-items:center;gap:14px;padding:14px 18px;color:var(--ink);text-decoration:none}
.lesson-list .no{font-weight:700;color:var(--accent);font-size:13px;width:26px;flex:none}
.lesson-list .t{font-weight:600}
.lesson-list .d{font-size:13px;color:var(--ink2)}
.lesson-list .st{margin-left:auto;font-size:13px;color:var(--muted);flex:none}
.lesson-list .st.done{color:var(--goodtext);font-weight:600}
.lesson-nav{display:flex;justify-content:space-between;gap:12px;margin:44px 0 10px;max-width:780px}
.lesson-nav a{flex:1;border:1px solid var(--ring);background:var(--surface);border-radius:12px;padding:12px 16px;
  text-decoration:none;color:var(--ink);font-size:14px}
.lesson-nav a span{display:block;font-size:12px;color:var(--muted)}
.lesson-nav a.next{text-align:right}
.complete-row{margin:34px 0;display:flex;align-items:center;gap:14px}
.complete-msg{font-size:14px;color:var(--goodtext);font-weight:600;display:none}
.tiles{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:12px;margin:18px 0 8px}
.tile{background:var(--surface);border:1px solid var(--ring);border-radius:12px;padding:14px 16px}
.tile .v{font-size:24px;font-weight:650}
.tile .k{color:var(--ink2);font-size:13px}
@media(max-width:640px){h1{font-size:24px} .ctrl input[type=range]{width:130px}
  .topnav .in{flex-wrap:wrap;gap:8px 14px;padding:8px 16px}
  .topnav a.nl{font-size:13.5px}
  .topnav .right{gap:8px}
  .wrap{padding:0 16px}
  .katex{font-size:.92em}
  .pill{font-size:11px}
  .ctrl,.readout{min-width:0 !important;max-width:100%;box-sizing:border-box}
  .ctrl input[type=range],.ctrl select,.ctrl input[type=number]{width:100% !important;max-width:100%}}

/* figure download buttons */
.dlrow{display:flex;gap:8px;justify-content:flex-end;margin-top:4px}
.dlbtn{font:600 11.5px system-ui,-apple-system,"Segoe UI",sans-serif;color:var(--ink2);
  background:transparent;border:1px solid var(--grid);border-radius:7px;padding:4px 9px;cursor:pointer}
.dlbtn:hover{border-color:var(--baseline);color:var(--ink)}

/* formula-card "more explanation" dropdown */
.formula-card details.explain{margin-top:10px;border-top:1px dashed var(--grid);padding-top:8px}
.formula-card details.explain summary{cursor:pointer;font:600 12.5px system-ui,-apple-system,"Segoe UI",sans-serif;
  color:var(--s1);list-style:none;display:inline-flex;align-items:center;gap:6px}
.formula-card details.explain summary::-webkit-details-marker{display:none}
.formula-card details.explain summary::after{content:"▾";transition:transform .2s}
.formula-card details.explain[open] summary::after{transform:rotate(180deg)}
.formula-card details.explain .body{font-size:13.5px;line-height:1.75;color:var(--ink2);padding-top:8px}
.formula-card details.explain .body b{color:var(--ink)}

/* ---------- module tests ---------- */
.quizbar{position:sticky;top:47px;z-index:40;background:var(--surface);border:1px solid var(--ring);
  border-radius:12px;max-width:780px;margin:18px 0;box-shadow:0 4px 14px rgba(0,0,0,.06)}
.quizbar .in{display:flex;align-items:center;gap:18px;padding:10px 18px;flex-wrap:wrap}
.qtime{font-size:22px;font-weight:700;font-variant-numeric:tabular-nums}
.qtime.low{color:var(--crit,#c0392b)}
.qcount{color:var(--ink2);font-size:14px}
.quizbar .btn{margin-left:auto}
.qcard{background:var(--surface);border:1px solid var(--ring);border-radius:12px;padding:16px 18px;margin:14px 0;max-width:780px}
.qcard .qtext{margin:6px 0 10px;font-size:15.5px}
.qopts{display:flex;flex-direction:column;gap:8px}
.qopt{display:flex;gap:10px;align-items:baseline;padding:8px 12px;border:1px solid var(--grid);
  border-radius:9px;cursor:pointer;font-size:14.5px}
.qopt:hover{border-color:var(--accent)}
.qcard.right{border-left:4px solid #2e9e5b}
.qcard.wrong{border-left:4px solid #c0392b}
.qcard .mark{font-size:13px;color:var(--ink2)}
.qcard.right .mark{color:#2e9e5b}
.qcard.wrong .mark{color:#c0392b}
.youranswer{color:#c0392b;font-size:14px;margin:4px 0}
.correctanswer{color:#2e9e5b;font-size:14px;margin:4px 0}
.qcard .why{font-size:14px;color:var(--ink2);border-top:1px dashed var(--grid);margin-top:8px;padding-top:8px}
.qcard .reread{font-size:13.5px;margin:8px 0 0}
.result-head{display:flex;gap:22px;align-items:center;background:var(--surface);border:1px solid var(--ring);
  border-radius:14px;padding:20px 24px;margin:18px 0;max-width:780px}
.result-head .big{font-size:44px;font-weight:750;font-variant-numeric:tabular-nums}
.result-head.pass .big{color:#2e9e5b}
.result-head.fail .big{color:#c0392b}
.result-head .pct{font-size:16px;font-weight:600}
.result-head .verdict{color:var(--ink2);margin-top:2px}
.result-head .meta{color:var(--muted);font-size:12.5px;margin-top:4px}
.result-actions{display:flex;gap:10px;flex-wrap:wrap;margin:0 0 8px}
@media print{
  .topnav,.noprint,.crumbs,footer.site,.lesson-nav{display:none !important}
  body{background:#fff}
  .qcard,.result-head{break-inside:avoid;border-color:#ccc}
}

/* ---------- cheat sheets ---------- */
body.cheat{font-size:13.5px}
.cheat h1{font-size:24px;margin:4px 0 2px}
.cheat .sub{color:var(--muted);font-size:13px;margin:0 0 14px}
.cheat .cols{column-width:360px;column-gap:26px;max-width:1050px}
.cheat .cell{break-inside:avoid;border:1px solid var(--ring);border-radius:10px;
  padding:8px 14px;margin:0 0 12px;background:var(--surface)}
.cheat .cell .tag{font-size:11px;font-weight:700;letter-spacing:.07em;text-transform:uppercase;margin:2px 0 4px;color:var(--accent)}
.cheat .cell.warn .tag{color:#8a6200}
.cheat .cell p{margin:6px 0}
.cheat .katex-display{margin:6px 0;padding:2px 0}
.cheat .symbols{font-size:12px;margin-top:4px;padding-top:4px}
@media print{
  body.cheat{font-size:11.5px;background:#fff}
  .cheat .cols{column-count:2;column-width:auto;max-width:none}
  .cheat h1{font-size:19px}
  .cheat .cell{border-color:#ccc;padding:5px 10px;margin-bottom:8px}
  .cheat .katex{font-size:1em}
}