:root{
  --ink:#1a1f24;
  --muted:#5c6670;
  --line:#d9dee3;
  --bg:#f4f6f8;
  --card:#ffffff;
  --accent:#2a6b4f;      /* AQA-ish green */
  --accent-soft:#e7f1ec;
  --blue:#245a8d;
  --right:#1f8a4c;
  --right-soft:#e4f4ea;
  --wrong:#b23b3b;
  --wrong-soft:#f7e6e6;
  --warn:#b26a00;
  --radius:10px;
  --shadow:0 1px 2px rgba(0,0,0,.05),0 2px 8px rgba(0,0,0,.04);
  --mono:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --sans:system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
}
*{box-sizing:border-box}
html,body{margin:0}
body{
  font-family:var(--sans);
  color:var(--ink);
  background:var(--bg);
  line-height:1.5;
  font-size:16.5px;
}
.wrap{max-width:860px;margin:0 auto;padding:0 18px}

/* top bar */
.topbar{background:var(--accent);color:#fff;padding:12px 0}
.topbar .wrap{display:flex;justify-content:space-between;align-items:baseline;gap:12px;flex-wrap:wrap}
.brand{font-weight:600}
.board{font-size:.82rem;opacity:.9}

.foot{border-top:1px solid var(--line);margin-top:40px;padding:16px 0;color:var(--muted);font-size:.8rem}

/* landing */
.lead{margin:26px 0 6px}
.lead h1{font-size:1.45rem;margin:0 0 4px}
.lead p{color:var(--muted);margin:.2rem 0}

.modes{display:flex;gap:10px;margin:18px 0 8px;flex-wrap:wrap}
.mode-btn{
  flex:1;min-width:220px;text-align:left;cursor:pointer;
  background:var(--card);border:1.5px solid var(--line);border-radius:var(--radius);
  padding:14px 16px;box-shadow:var(--shadow);transition:border-color .15s,background .15s;
}
.mode-btn[aria-pressed="true"]{border-color:var(--accent);background:var(--accent-soft)}
.mode-btn b{display:block;font-size:1rem}
.mode-btn span{color:var(--muted);font-size:.86rem}

.papers{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:12px;margin:14px 0 30px}
.paper{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:14px 16px;box-shadow:var(--shadow);display:flex;flex-direction:column;gap:8px;
}
.paper h3{margin:0;font-size:1.02rem}
.paper .meta{color:var(--muted);font-size:.82rem}
.paper .topics{font-size:.78rem;color:var(--muted)}
.paper.pending{opacity:.6}
.paper .best{font-size:.78rem;color:var(--accent);font-weight:600}
.start{
  margin-top:auto;align-self:flex-start;cursor:pointer;border:none;
  background:var(--accent);color:#fff;font-weight:600;font-size:.9rem;
  padding:8px 14px;border-radius:8px;
}
.start:disabled{background:#9fb2a9;cursor:not-allowed}

/* exam shell */
.examhead{
  position:sticky;top:0;z-index:5;background:var(--bg);
  border-bottom:1px solid var(--line);padding:10px 0;margin-bottom:14px;
}
.examhead .wrap{display:flex;align-items:center;gap:14px;flex-wrap:wrap}
.examhead .title{font-weight:600}
.examhead .spacer{flex:1}
.timer{font-family:var(--mono);font-weight:600;background:#fff;border:1px solid var(--line);
  border-radius:8px;padding:4px 10px}
.timer.low{color:var(--wrong);border-color:var(--wrong)}
.ghost{background:#fff;border:1px solid var(--line);border-radius:8px;padding:6px 12px;cursor:pointer;font-size:.86rem}
.ghost:hover{border-color:var(--accent)}

.progress{font-size:.82rem;color:var(--muted)}

/* question card */
.q{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:18px 20px;margin-bottom:16px}
.q .qhead{display:flex;justify-content:space-between;gap:10px;align-items:baseline;margin-bottom:6px}
.q .qnum{font-weight:700}
.q .qtopic{font-size:.74rem;color:#fff;background:var(--blue);padding:2px 8px;border-radius:20px;white-space:nowrap}
.q .marks{font-size:.82rem;color:var(--muted);white-space:nowrap}
.q .stem{margin:6px 0 12px}
.q .stem p{margin:.5em 0}
.q figure{margin:12px 0;text-align:center}
.q figure svg{max-width:100%;height:auto}
.q figcaption{font-size:.78rem;color:var(--muted);margin-top:4px}
.q table.data{border-collapse:collapse;margin:10px auto;font-size:.95rem}
.q table.data th,.q table.data td{border:1px solid var(--line);padding:5px 12px;text-align:center}
.q table.data th{background:var(--accent-soft)}

/* options */
.opts{display:flex;flex-direction:column;gap:8px;margin:8px 0}
.opt{display:flex;gap:10px;align-items:flex-start;border:1.5px solid var(--line);
  border-radius:8px;padding:9px 12px;cursor:pointer;background:#fff;transition:border-color .12s,background .12s}
.opt:hover{border-color:var(--accent)}
.opt input{margin-top:3px}
.opt.sel{border-color:var(--accent);background:var(--accent-soft)}
.opt.correct{border-color:var(--right);background:var(--right-soft)}
.opt.incorrect{border-color:var(--wrong);background:var(--wrong-soft)}
.opt .key{font-weight:600;margin-right:2px}

/* numeric / short input */
.answerline{display:flex;align-items:center;gap:8px;margin:8px 0;flex-wrap:wrap}
.answerline input[type=text]{font-size:1rem;padding:8px 10px;border:1.5px solid var(--line);
  border-radius:8px;min-width:140px;font-family:var(--mono)}
.answerline input.correct{border-color:var(--right);background:var(--right-soft)}
.answerline input.incorrect{border-color:var(--wrong);background:var(--wrong-soft)}
.answerline .unit{color:var(--muted)}

/* extended / self-mark */
.extended textarea{width:100%;min-height:90px;font-family:var(--sans);font-size:.98rem;
  padding:10px;border:1.5px solid var(--line);border-radius:8px;resize:vertical}
.selfmark{margin-top:10px;padding:12px;border:1px dashed var(--line);border-radius:8px;background:#fafbfc}
.selfmark h4{margin:.2rem 0 .4rem;font-size:.9rem}
.selfmark ul{margin:.3rem 0;padding-left:1.2rem}
.selfmark li{margin:.2rem 0}
.selfmark .award{display:flex;gap:8px;align-items:center;margin-top:8px;flex-wrap:wrap}
.selfmark .award button{border:1px solid var(--line);background:#fff;border-radius:6px;
  width:34px;height:34px;cursor:pointer;font-weight:600}
.selfmark .award button[aria-pressed="true"]{background:var(--accent);color:#fff;border-color:var(--accent)}

/* feedback block */
.fb{margin-top:12px;padding:12px 14px;border-radius:8px;font-size:.95rem}
.fb.ok{background:var(--right-soft);border:1px solid var(--right)}
.fb.no{background:var(--wrong-soft);border:1px solid var(--wrong)}
.fb .verdict{font-weight:700;margin-bottom:4px}
.fb .work{margin-top:6px}
.fb .work b{color:var(--ink)}

.submitrow{display:flex;gap:10px;margin:10px 0 2px;flex-wrap:wrap}
.btn{border:none;background:var(--accent);color:#fff;font-weight:600;padding:9px 16px;
  border-radius:8px;cursor:pointer;font-size:.92rem}
.btn:hover{filter:brightness(1.05)}
.btn.sec{background:#fff;color:var(--ink);border:1px solid var(--line)}

/* palette / nav */
.navrow{display:flex;justify-content:space-between;gap:10px;margin:18px 0;flex-wrap:wrap}
.palette{display:flex;flex-wrap:wrap;gap:6px;margin:10px 0 20px}
.palette button{width:36px;height:36px;border:1px solid var(--line);background:#fff;
  border-radius:7px;cursor:pointer;font-size:.82rem;font-weight:600}
.palette button.done{background:var(--accent-soft);border-color:var(--accent)}
.palette button.current{outline:2px solid var(--blue)}
.palette button.flagged{position:relative}
.palette button.flagged::after{content:"";position:absolute;top:2px;right:2px;width:7px;height:7px;background:var(--warn);border-radius:50%}

/* results */
.result{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:22px;margin:18px 0}
.score{font-size:2.4rem;font-weight:800;color:var(--accent)}
.score small{font-size:1rem;color:var(--muted);font-weight:500}
.gradebar{height:12px;border-radius:6px;background:linear-gradient(90deg,#c44,#e0a84a,#6b4,#2a6b4f);margin:12px 0}
.bytopic{width:100%;border-collapse:collapse;margin-top:14px;font-size:.92rem}
.bytopic th,.bytopic td{border-bottom:1px solid var(--line);padding:7px 8px;text-align:left}
.bytopic td.n{text-align:right;font-family:var(--mono)}
.gradenote{color:var(--muted);font-size:.85rem;margin-top:8px}

.refpanel{background:var(--card);border:1px solid var(--accent);border-radius:var(--radius);box-shadow:var(--shadow);padding:14px 18px;margin-bottom:16px;font-size:.92rem}
.refpanel h4{margin:.5rem 0 .3rem;font-size:.86rem;text-transform:uppercase;letter-spacing:.04em;color:var(--accent)}
.refpanel h4:first-child{margin-top:0}
.refpanel table{border-collapse:collapse;margin:4px 0}
.refpanel td,.refpanel th{border:1px solid var(--line);padding:2px 7px;text-align:center;font-size:.82rem;font-family:var(--mono)}
.refpanel ul{margin:.3rem 0;padding-left:1.1rem}
.refpanel li{margin:2px 0}
.refpanel .eq{font-family:var(--mono);font-size:.9rem}
.refpanel .note{color:var(--muted);font-size:.82rem}

.revise{margin-top:10px;font-size:.93rem}
.revise a{color:var(--blue);font-weight:600;text-decoration:none}
.revise a:hover{text-decoration:underline}
.revise .src{color:var(--muted);font-size:.8rem;margin-left:4px}
.revise-sm{color:var(--blue);font-size:.82rem;text-decoration:none;white-space:nowrap;margin-left:6px}
.revise-sm:hover{text-decoration:underline}

.hidden{display:none !important}
@media print{.examhead,.palette,.submitrow,.navrow,.foot,.topbar{display:none}.q{break-inside:avoid}}