:root{
  --slate:#3c3a4f;        /* Cirrus dark header */
  --slate-2:#4a4860;
  --green:#1f8a5b;        /* Cirrus action green */
  --green-d:#15724a;
  --orange:#ee6a2b;       /* Cirrus accent (logo / question no.) */
  --line:#e7e7ee;
  --line-2:#d9d9e2;
  --ink:#24262f;
  --muted:#73768a;
  --bg:#eef0f3;
  --card:#ffffff;
  --sel:#eef4ff;
  --sel-bd:#9db8e6;
  --good:#1f8a5b;
  --bad:#cf3b3b;
  --good-bg:#edf7f1;
  --bad-bg:#fbecec;
}
*{box-sizing:border-box;margin:0;padding:0}
html,body{height:100%}
body{
  font-family:"Inter","Segoe UI",system-ui,-apple-system,Roboto,Helvetica,Arial,sans-serif;
  background:var(--bg);color:var(--ink);line-height:1.55;
  -webkit-font-smoothing:antialiased;font-size:15px;
}
main{max-width:900px;margin:0 auto;padding:28px 18px 96px}

/* ---------- Top bar ---------- */
.topbar{
  position:sticky;top:0;z-index:30;
  display:flex;align-items:center;justify-content:space-between;gap:16px;
  background:var(--slate);color:#fff;padding:0 18px;height:54px;
  box-shadow:0 1px 0 rgba(0,0,0,.08);
}
.brand{display:flex;align-items:center;gap:9px;font-weight:600;font-size:1.15rem;letter-spacing:.2px}
.brand-mark{width:22px;height:22px;border-radius:6px}
.timer{
  background:#fbf7ea;color:#46443a;border:1px solid #e7dcb6;
  padding:5px 14px;border-radius:5px;font-size:.86rem;
}
.timer strong{font-variant-numeric:tabular-nums}
.topbar-right{display:flex;align-items:center;gap:14px}
.user{opacity:.8;font-size:.86rem}
.calc-toggle{
  background:transparent;color:#fff;border:1px solid #6a6880;
  padding:6px 12px;border-radius:5px;cursor:pointer;font-size:.84rem;transition:.12s;
}
.calc-toggle:hover{background:rgba(255,255,255,.1)}

/* ---------- Buttons ---------- */
.btn{border:1px solid var(--green);background:var(--green);color:#fff;
  padding:8px 17px;border-radius:5px;font-size:.9rem;cursor:pointer;font-weight:600;transition:.12s}
.btn:hover{background:var(--green-d);border-color:var(--green-d)}
.btn.ghost{background:#fff;color:var(--green)}
.btn.ghost:hover{background:#f1f8f4}
.btn.gray{background:#fff;color:var(--ink);border-color:var(--line-2)}
.btn.gray:hover{background:#f4f4f7;border-color:#c7c7d2}
.btn:disabled{opacity:.4;cursor:not-allowed}

/* ---------- Cards / home ---------- */
.card{background:var(--card);border:1px solid var(--line);border-radius:8px;padding:26px 28px;
  box-shadow:0 1px 2px rgba(20,20,40,.04)}
.home-hero{text-align:center;padding:46px 20px 6px}
.home-hero h1{font-size:1.75rem;font-weight:700;letter-spacing:-.02em}
.home-hero p{color:var(--muted);margin-top:8px;font-size:.95rem}
.exam-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:14px;margin-top:24px}
.exam-tile{display:flex;flex-direction:column;gap:9px;cursor:pointer;transition:.15s;
  border-top:3px solid var(--orange);padding:20px 22px}
.exam-tile:hover{transform:translateY(-2px);box-shadow:0 8px 22px rgba(20,20,40,.09);border-color:var(--line-2)}
.exam-tile.locked{cursor:not-allowed;opacity:.65;border-top-color:#cfcfd8}
.exam-tile h3{font-size:1.05rem;font-weight:650}
.exam-tile .meta{color:var(--muted);font-size:.83rem}
.exam-tile .tag{align-self:flex-start;background:#fdece2;color:var(--orange);
  font-size:.68rem;font-weight:700;padding:3px 9px;border-radius:4px;text-transform:uppercase;letter-spacing:.05em}
.exam-tile.locked .tag{background:#ededf0;color:#8a8a93}
.exam-tile .go{margin-top:auto;color:var(--green);font-weight:600;font-size:.88rem}

/* ---------- Intro ---------- */
.intro h1{font-size:1.4rem;font-weight:700;margin-bottom:3px}
.intro .sub{color:var(--muted);margin-bottom:20px;font-size:.92rem}
.banner-ok{background:#ecf4fa;border:1px solid #cfe2f1;color:#28658c;
  padding:12px 16px;border-radius:6px;display:flex;align-items:center;gap:10px;margin-bottom:18px;font-size:.92rem}
.banner-ok .check{color:var(--green);font-size:1.1rem}
.details{border:1px solid var(--line);border-radius:6px;overflow:hidden;margin-bottom:22px}
.details .dh{background:#f7f7fa;padding:9px 16px;font-weight:700;color:var(--muted);
  text-transform:uppercase;font-size:.74rem;letter-spacing:.07em;border-bottom:1px solid var(--line)}
.details table{width:100%;border-collapse:collapse}
.details td{padding:10px 16px;border-bottom:1px solid var(--line);font-size:.9rem}
.details td.k{color:var(--muted);width:26%}
.details tr:last-child td{border-bottom:none}

/* ---------- Runner ---------- */
.qhead{display:flex;justify-content:space-between;align-items:baseline;
  color:var(--muted);font-size:.78rem;text-transform:uppercase;letter-spacing:.06em;margin-bottom:16px;
  padding-bottom:12px;border-bottom:1px solid var(--line)}
.qnum-badge{background:var(--orange);color:#fff;border-radius:4px;padding:1px 8px;
  font-weight:700;margin:0 3px;letter-spacing:0}
.examtitle{font-size:.95rem;font-weight:700;color:var(--ink);text-transform:none;letter-spacing:0;margin-bottom:4px}
.qintro{margin:4px 0 14px;font-size:.96rem}
.qintro p{margin:8px 0}
.qintro ul{margin:8px 0 8px 20px}
.qfig{margin:14px 0;text-align:center}
.qfig img{max-width:100%;border:1px solid var(--line);border-radius:6px;background:#fff}
.dtable{border-collapse:collapse;margin:12px 0;font-size:.88rem}
.dtable th,.dtable td{border:1px solid var(--line-2);padding:5px 12px;text-align:center}
.dtable th{background:#f7f7fa;font-weight:650}

.part{margin:20px 0 8px}
.part+.part{border-top:1px dashed var(--line);padding-top:18px}
.part-prompt{font-weight:600;margin-bottom:5px}
.part-hint{color:var(--muted);font-size:.74rem;text-transform:uppercase;letter-spacing:.05em;margin-bottom:10px}
.opt{display:flex;gap:11px;align-items:flex-start;border:1px solid var(--line-2);
  border-radius:5px;padding:10px 14px;margin:7px 0;cursor:pointer;background:#fff;transition:.1s}
.opt:hover{border-color:#b3b3c2;background:#fafafc}
.opt.sel{border-color:var(--sel-bd);background:var(--sel);box-shadow:inset 0 0 0 1px var(--sel-bd)}
.opt input{margin-top:3px;accent-color:var(--green);width:15px;height:15px;flex:none}
.opt .lab{font-weight:700;margin-right:1px}
.opt.correct{border-color:var(--good);background:var(--good-bg)}
.opt.wrong{border-color:var(--bad);background:var(--bad-bg)}
.opt .mark{margin-left:auto;font-weight:700;font-size:.85rem;white-space:nowrap}
.opt.correct .mark{color:var(--good)}
.opt.wrong .mark{color:var(--bad)}
.fill-input{width:260px;max-width:100%;padding:9px 12px;border:1px solid var(--line-2);border-radius:5px;font-size:.95rem}
.fill-input:focus{outline:none;border-color:var(--sel-bd);box-shadow:0 0 0 2px var(--sel)}

.clearlink{display:inline-block;color:var(--green);background:none;border:none;
  cursor:pointer;font-size:.84rem;margin-top:8px;padding:0}
.clearlink:hover{text-decoration:underline}

.runbar{position:sticky;bottom:0;background:#fff;border-top:1px solid var(--line);
  margin:28px -18px -96px;padding:13px 18px;display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;
  box-shadow:0 -1px 6px rgba(20,20,40,.04)}
.runbar .grp{display:flex;gap:9px;flex-wrap:wrap}

/* overview modal */
.overlay{position:fixed;inset:0;background:rgba(22,22,34,.5);z-index:40;display:flex;align-items:center;justify-content:center;padding:20px}
.modal{background:#fff;border-radius:8px;max-width:560px;width:100%;padding:24px;max-height:85vh;overflow:auto}
.modal h2{margin-bottom:12px;font-size:1.2rem}
.ov-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(44px,1fr));gap:7px;margin:14px 0}
.ov-cell{aspect-ratio:1;border:1px solid var(--line-2);border-radius:5px;display:flex;
  align-items:center;justify-content:center;cursor:pointer;font-weight:600;font-size:.88rem;position:relative}
.ov-cell:hover{border-color:var(--green)}
.ov-cell.answered{background:#ecf4fa;border-color:var(--sel-bd)}
.ov-cell.marked::after{content:"";position:absolute;top:3px;right:3px;width:7px;height:7px;background:var(--orange);border-radius:50%}
.ov-cell.current{outline:2px solid var(--green);outline-offset:1px}
.legend{display:flex;gap:18px;flex-wrap:wrap;color:var(--muted);font-size:.8rem;margin-top:6px}
.legend i{width:12px;height:12px;border-radius:3px;display:inline-block;margin-right:5px;vertical-align:-1px}
.mark-btn.on{background:var(--orange);border-color:var(--orange);color:#fff}

/* ---------- Result ---------- */
.result-head{text-align:center;padding:8px 0 4px}
.result-head h1{font-size:1.35rem;font-weight:700}
.grade-circle{width:140px;height:140px;border-radius:50%;margin:16px auto;display:flex;
  flex-direction:column;align-items:center;justify-content:center;color:#fff;font-weight:800;
  box-shadow:0 8px 26px rgba(0,0,0,.13)}
.grade-circle.pass{background:linear-gradient(135deg,#1f8a5b,#2bb673)}
.grade-circle.fail{background:linear-gradient(135deg,#cf3b3b,#e8693f)}
.grade-circle .g{font-size:2.6rem;line-height:1}
.grade-circle .l{font-size:.74rem;font-weight:600;opacity:.92;margin-top:4px;text-transform:uppercase;letter-spacing:.06em}
.score-line{text-align:center;color:var(--muted);margin-bottom:8px;font-size:.9rem}
.sec-scores{display:grid;grid-template-columns:repeat(auto-fill,minmax(160px,1fr));gap:11px;margin:18px 0}
.sec-scores .sc{border:1px solid var(--line);border-radius:6px;padding:12px 14px}
.sec-scores .sc b{display:block;font-size:1.15rem}
.sec-scores .sc span{color:var(--muted);font-size:.8rem}
.review-q{border:1px solid var(--line);border-radius:8px;padding:16px 18px;margin:13px 0}
.review-q .rh{display:flex;justify-content:space-between;font-size:.78rem;color:var(--muted);margin-bottom:8px;
  text-transform:uppercase;letter-spacing:.04em}
.pill{padding:1px 9px;border-radius:4px;font-size:.74rem;font-weight:700}
.pill.good{background:var(--good-bg);color:var(--good)}
.pill.bad{background:var(--bad-bg);color:var(--bad)}

/* ---------- Calculator ---------- */
.calculator{position:fixed;top:84px;right:24px;width:288px;background:#2b2a3a;color:#fff;
  border-radius:10px;box-shadow:0 16px 50px rgba(0,0,0,.42);z-index:50;overflow:hidden;user-select:none}
.calc-head{display:flex;justify-content:space-between;align-items:center;padding:10px 14px;
  background:#1f1e2c;cursor:move;font-size:.86rem;font-weight:600}
.calc-close{background:none;border:none;color:#fff;cursor:pointer;font-size:1rem;opacity:.8}
.calc-close:hover{opacity:1}
.calc-display{width:calc(100% - 24px);margin:12px;padding:11px;border:none;border-radius:6px;
  background:#12111b;color:#fff;font-size:1.2rem;text-align:right;font-family:"SF Mono",Menlo,monospace}
.calc-grid{display:grid;grid-template-columns:repeat(5,1fr);gap:6px;padding:0 12px 14px}
.calc-grid button{padding:11px 0;border:none;border-radius:6px;background:#3d3b52;color:#fff;
  cursor:pointer;font-size:.92rem;transition:.1s}
.calc-grid button:hover{background:#4b4866}
.calc-grid button.op{background:#54507a}
.calc-grid button.op:hover{background:#635d90}
.calc-grid button.eq{background:var(--green)}
.calc-grid button.eq:hover{background:var(--green-d)}
.calc-grid button.fn{background:#343349;font-size:.78rem}

@media(max-width:560px){
  .calculator{right:8px;left:8px;width:auto}
  .runbar .grp{width:100%}
  main{padding:18px 12px 96px}
  .card{padding:20px 18px}
}