:root{
  --bg:#0b0d17; --panel:#141826; --panel2:#1b2030; --line:#272d40;
  --text:#e7ebf3; --muted:#9aa3b8; --faint:#6b7488;
  --purple:#7c5cff; --blue:#3b6fe0; --cyan:#22b3c9; --green:#2ec07a; --red:#ef5350; --yellow:#e0a32e;
  --grad:linear-gradient(90deg,#7c5cff,#3b6fe0,#22b3c9);
}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--text);font-family:'Manrope',-apple-system,Segoe UI,Roboto,sans-serif;line-height:1.6;}
code,.code,pre{font-family:'JetBrains Mono',ui-monospace,Menlo,Consolas,monospace;}
a{color:var(--cyan);text-decoration:none} a:hover{text-decoration:underline}

/* top bar */
.topbar{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:14px 22px;background:var(--panel);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:5;flex-wrap:wrap}
.brand{font-weight:800;font-size:18px;background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent;}
.topbar nav{display:flex;gap:6px;flex-wrap:wrap}
.topbar nav a{color:var(--muted);padding:7px 12px;border-radius:8px;font-size:14px;font-weight:600}
.topbar nav a:hover{color:var(--text);background:var(--panel2);text-decoration:none}
.topbar nav a.on{color:#fff;background:linear-gradient(90deg,rgba(124,92,255,.25),rgba(34,179,201,.18));}

.wrap{max-width:920px;margin:26px auto;padding:0 18px}
.foot{max-width:920px;margin:30px auto;padding:18px;color:var(--faint);font-size:12px;border-top:1px solid var(--line)}

.card{background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:22px 24px;margin-bottom:18px}
h1{font-size:24px;margin:0 0 8px} h2{font-size:18px;margin:18px 0 10px} h3{font-size:15px;margin:14px 0 6px;color:#cdd5e8}
.muted{color:var(--muted)} .small{font-size:13px} .faint{color:var(--faint)}
.back{display:inline-block;margin-bottom:8px;color:var(--muted)}

/* progress + module list */
.progress{height:10px;background:var(--panel2);border-radius:6px;overflow:hidden;margin:10px 0 4px}
.progress .bar{height:100%;background:var(--grad)}
.modlist{display:flex;flex-direction:column;gap:10px}
.modrow{display:flex;align-items:center;gap:16px;background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px 16px}
.modrow.locked{opacity:.55}
.modrow.done{border-color:rgba(46,192,122,.4)}
.modrow.open{border-color:rgba(124,92,255,.45)}
.modrow.final{border-style:dashed}
.modnum{width:38px;height:38px;flex:0 0 38px;border-radius:10px;display:flex;align-items:center;justify-content:center;font-weight:800;background:var(--panel2);color:var(--cyan)}
.modrow.done .modnum{background:rgba(46,192,122,.18);color:var(--green)}
.modmeta{flex:1} .modtitle{font-weight:700}
.modaction .lock{font-size:18px;opacity:.6}

/* buttons */
.btn{display:inline-block;background:var(--panel2);color:var(--text);border:1px solid var(--line);padding:9px 16px;border-radius:9px;font-weight:700;font-size:14px;cursor:pointer}
.btn:hover{text-decoration:none;border-color:var(--purple)}
.btn.primary{background:var(--grad);border:none;color:#fff}
.btnrow{display:flex;gap:10px;flex-wrap:wrap;margin-top:14px}
.linkbtn{background:none;border:none;color:var(--cyan);cursor:pointer;font-size:13px;padding:0;font-family:inherit}
.linkbtn:hover{text-decoration:underline}
.inline{display:inline}

/* forms */
label{display:block;margin:10px 0;font-size:14px;color:var(--muted)}
input,select{width:100%;margin-top:5px;background:var(--panel2);border:1px solid var(--line);border-radius:8px;color:var(--text);padding:9px 11px;font-size:14px;font-family:inherit}
input:focus,select:focus{outline:none;border-color:var(--purple)}
.chk{display:flex;align-items:center;gap:8px} .chk input{width:auto;margin:0}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:8px 16px}
.grid2 > div{grid-column:1/-1}

/* flash */
.flash{padding:11px 14px;border-radius:9px;margin:12px 0;font-size:14px;border:1px solid}
.flash.ok{background:rgba(46,192,122,.12);border-color:rgba(46,192,122,.5);color:#a7e9c6}
.flash.err{background:rgba(239,83,80,.12);border-color:rgba(239,83,80,.5);color:#f3b1af}
.flash.warn{background:rgba(224,163,46,.12);border-color:rgba(224,163,46,.5);color:#eccf93}

/* lesson content */
.lesson h1{font-size:22px;border-bottom:2px solid var(--purple);padding-bottom:6px;margin-top:6px}
.lesson h2{font-size:17px;color:#fff;background:rgba(124,92,255,.14);padding:6px 10px;border-radius:6px}
.lesson h3{font-size:15px;color:var(--cyan)}
.lesson p{color:#d7dcea}
.lesson ul,.lesson ol{padding-left:22px;color:#d7dcea}
.lesson li{margin:4px 0}
.lesson code{background:var(--panel2);padding:1px 5px;border-radius:4px;font-size:13px;color:#cdd5e8}
.lesson pre.code{background:#0e1120;border:1px solid var(--line);border-radius:8px;padding:12px;overflow:auto;font-size:12.5px}

/* tables */
table.ct{width:100%;border-collapse:collapse;margin:10px 0;font-size:13.5px}
table.ct th{background:var(--purple);color:#fff;text-align:left;padding:7px 10px;font-size:12.5px}
table.ct td{border-bottom:1px solid var(--line);padding:7px 10px;color:#d7dcea;vertical-align:top}

/* quiz */
.quizcard{border-color:rgba(124,92,255,.35)}
.qz{padding:14px 0;border-bottom:1px solid var(--line)}
.qzq{font-weight:700;margin-bottom:8px} .qn{color:var(--cyan);margin-right:4px}
.qzc{display:flex;gap:10px;align-items:flex-start;background:var(--panel2);border:1px solid var(--line);border-radius:8px;padding:9px 12px;margin:6px 0;cursor:pointer;color:#d7dcea}
.qzc input{width:auto;margin:3px 0 0}
.qzc.correct{border-color:var(--green);background:rgba(46,192,122,.12)}
.qzc.wrong{border-color:var(--red);background:rgba(239,83,80,.12)}
.explain{margin-top:6px;color:var(--muted);font-style:italic}

/* pills + tabs */
.pill{display:inline-block;background:var(--panel2);border:1px solid var(--line);border-radius:10px;padding:1px 9px;font-size:12px;color:var(--muted)}
.pill.green{color:#a7e9c6;border-color:rgba(46,192,122,.5)}
.tabs{display:flex;gap:6px;flex-wrap:wrap;margin:10px 0}
.tabs a{padding:7px 12px;border-radius:8px;color:var(--muted);background:var(--panel2);font-size:13px;font-weight:600}
.tabs a.on{color:#fff;background:linear-gradient(90deg,rgba(124,92,255,.3),rgba(34,179,201,.2))}

/* auth */
body.auth{display:flex;align-items:center;justify-content:center;min-height:100vh;background:radial-gradient(1200px 600px at 50% -10%,rgba(124,92,255,.18),transparent),var(--bg)}
.auth-card{max-width:380px;width:92%}
.auth-card .brand{display:block;margin-bottom:10px;font-size:20px}

@media(max-width:560px){.grid2{grid-template-columns:1fr}}

/* ---- labs / simulators ---- */
.simgrid{display:grid;grid-template-columns:300px 1fr;gap:20px}
.siminputs{display:flex;flex-direction:column;gap:4px}
.siminput{font-size:12px;color:var(--muted)} .siminput input{margin-top:3px}
.outgrid{display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-bottom:14px}
.ostat{background:var(--panel2);border:1px solid var(--line);border-radius:8px;padding:8px 10px;display:flex;flex-direction:column}
.ostat .ok{font-size:11px;color:var(--muted)} .ostat .ov{font-size:17px;font-weight:700}
.neg{color:var(--red)}
.breaks{display:grid;grid-template-columns:1fr 1fr 1fr;gap:8px}
.bp{background:var(--panel2);border:1px solid var(--line);border-radius:8px;padding:8px 10px;display:flex;flex-direction:column;gap:2px}
.bp b{font-size:16px;color:var(--cyan)}
.scorewrap{display:grid;grid-template-columns:220px 1fr;gap:20px;align-items:start}
.scorebox{background:var(--panel2);border:1px solid var(--line);border-radius:12px;padding:18px;text-align:center}
.scorebox .bignum{font-size:46px;font-weight:800;line-height:1}
.scorebox .band{display:inline-block;margin-top:10px;color:#fff;padding:3px 12px;border-radius:10px;font-weight:700}
.assumgrid{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}
.acell{background:var(--panel2);border:1px solid var(--line);border-radius:8px;padding:8px;display:flex;flex-direction:column;gap:4px}
.tmark{margin-top:6px}
.okmark{color:#a7e9c6;font-weight:700} .nomark{color:#f3b1af}
@media(max-width:680px){.simgrid,.scorewrap{grid-template-columns:1fr}.outgrid,.breaks,.assumgrid{grid-template-columns:1fr 1fr}}

/* classify / sequence / threshold sandboxes */
.clrow{display:flex;align-items:center;gap:12px;background:var(--panel2);border:1px solid var(--line);border-radius:8px;padding:10px 12px;margin:8px 0}
.clrow .cltext{flex:1;color:#d7dcea;font-size:14px}
.clrow select{max-width:240px}
.seqlist{display:flex;flex-direction:column;gap:6px}
.seqrow{display:flex;align-items:center;gap:12px;background:var(--panel2);border:1px solid var(--line);border-radius:8px;padding:10px 12px}
.seqn{width:26px;height:26px;flex:0 0 26px;border-radius:6px;background:var(--panel);display:flex;align-items:center;justify-content:center;font-weight:700;color:var(--cyan)}
.seqt{flex:1;color:#d7dcea}
.seqbtns .linkbtn{font-size:16px;padding:0 4px}
.verdict{margin-top:12px;background:var(--panel2);border:1px solid var(--line);border-left:4px solid var(--green);border-radius:8px;padding:12px 14px;font-weight:700}

/* practice tiles on the Cases tab */
.practice-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
.practice-tile{display:flex;flex-direction:column;gap:4px;background:var(--panel2);border:1px solid var(--line);border-radius:10px;padding:14px;text-decoration:none}
.practice-tile strong{color:#e8ecf6}
.practice-tile:hover{border-color:var(--cyan)}
@media(max-width:680px){.practice-grid{grid-template-columns:1fr 1fr}}