*{box-sizing:border-box;margin:0;padding:0;border-radius:0!important}
:root{--bg:#0b0b0b;--panel:#111111;--card:#141414;--input:#0e0e0e;--border:#2e2e2e;--border2:#3d3d3d;--edge:#626262;--txt:#e5e5e5;--body:#cccccc;--muted:#9a9a9a;--dim:#7d7d7d;--ok:#10b981;--cyan:#38bdf8;--amber:#f59e0b;--bad:#ff5555;--mono:'JetBrains Mono',ui-monospace,SFMono-Regular,Menlo,Consolas,monospace}
html{background:var(--bg)}
body{background:var(--bg);color:var(--body);font-family:var(--mono);font-size:14px;line-height:1.55;max-width:1180px;margin:0 auto;padding:0 16px 64px}
a{color:var(--cyan);text-decoration:none}
a:hover{text-decoration:underline}
h1{font-size:2.1rem;font-weight:600;letter-spacing:-.04em;color:#fff;line-height:1.15;margin:18px 0 10px}
h2{font-size:.76rem;font-weight:500;text-transform:uppercase;letter-spacing:.12em;color:var(--muted);margin:28px 0 12px;border-bottom:1px solid var(--border);padding-bottom:8px}
h3{color:#fff;font-size:1rem;margin:0 0 6px}
.topbar{display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--border);padding:12px 0;position:sticky;top:0;background:rgba(11,11,11,.92);z-index:5}
.brand{color:#fff;font-weight:600;font-size:1rem;letter-spacing:-.02em}
.brand span{color:var(--dim);font-weight:400;font-size:.78rem;margin-left:10px}
.nav{display:flex;gap:14px;align-items:center;font-size:.8rem}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:8px 18px;background:#161616;color:#ddd;border:1px solid var(--edge);font-size:.8rem;font-family:inherit;cursor:pointer;letter-spacing:.02em;transition:all .15s ease;text-decoration:none}
.btn:hover:not(:disabled){background:#242424;border-color:#555;color:#fff;text-decoration:none}
.btn:active:not(:disabled){background:#fff;color:#000;border-color:#fff}
.btn:disabled{opacity:.3;cursor:not-allowed}
.btn.primary{background:var(--cyan);border-color:var(--cyan);color:#001018;font-weight:600}
.btn.primary:hover{background:#7cd4fc;color:#000}
.btn.ok{border-color:var(--ok);color:var(--ok)}
.btn.danger{border-color:var(--bad);color:var(--bad)}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:14px}
.grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}
.card{background:var(--card);border:1px solid var(--border);padding:16px}
.card:hover{border-color:var(--border2)}
.meta{color:var(--muted);font-size:.78rem}
.dim{color:var(--dim);font-size:.78rem}
table{width:100%;border-collapse:collapse;font-size:.82rem}
th{color:var(--dim);text-transform:uppercase;letter-spacing:.1em;font-size:.68rem;text-align:left;padding:8px;border-bottom:1px solid var(--border)}
td{padding:8px;border-bottom:1px solid #1c1c1c;font-variant-numeric:tabular-nums}
input[type=text],input[type=email],input[type=number],select,textarea{background:var(--input);color:#e5e5e5;border:1px solid var(--edge);padding:9px 12px;font-family:inherit;font-size:.82rem;outline:none;width:100%}
input:focus,textarea:focus,select:focus{border-color:var(--cyan)}
input::placeholder{color:var(--dim)}
label{display:block;font-size:.75rem;color:var(--muted);margin:10px 0 4px;text-transform:uppercase;letter-spacing:.08em}
.chk{display:flex;gap:10px;align-items:flex-start;border:1px solid var(--edge);padding:10px 12px;margin:6px 0;background:var(--panel);cursor:pointer;font-size:.85rem}
.chk:hover{border-color:var(--border2)}
.chk input{width:auto;margin-top:3px;accent-color:var(--cyan)}
.palette{display:grid;grid-template-columns:repeat(5,1fr);gap:6px}
.pal{aspect-ratio:1;display:grid;place-items:center;border:1px solid var(--edge);background:var(--panel);color:var(--muted);font-size:.75rem;cursor:pointer;min-height:44px}
.pal.cur{border-color:var(--cyan);color:#fff}
.pal.ans{background:#12301f;border-color:var(--ok);color:var(--ok)}
.pal.rev{background:#2a1f05;border-color:var(--amber);color:var(--amber)}
.pal.skip{background:var(--panel)}
.opt{display:flex;gap:10px;align-items:flex-start;border:1px solid var(--edge);padding:10px 12px;margin:8px 0;background:var(--panel);cursor:pointer}
.opt:hover{border-color:var(--border2)}
.opt.sel{border-color:var(--cyan);background:#0d1b24}
.status-dot{width:6px;height:6px;background:#444;display:inline-block;flex:none}
.ok-t{color:var(--ok)}.bad-t{color:var(--bad)}.warn-t{color:var(--amber)}.cyan-t{color:var(--cyan)}
.bar{height:2px;background:#1c1c1c;overflow:hidden;margin-top:8px}
.bar i{display:block;height:100%;background:var(--ok)}
.seg{display:flex;height:10px;background:#1c1c1c;overflow:hidden}
.seg i{display:block;height:100%}
:focus-visible{outline:2px solid var(--cyan);outline-offset:2px}
.cbt{display:grid;grid-template-columns:1fr 220px;gap:14px}
.timer{font-variant-numeric:tabular-nums;color:var(--amber);font-weight:600}
.kv{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;margin:14px 0}
.kv .card b{display:block;font-size:1.5rem;color:#fff;font-variant-numeric:tabular-nums}
footer{margin-top:48px;border-top:1px solid var(--border);padding-top:16px;color:var(--dim);font-size:.75rem;display:flex;justify-content:space-between;flex-wrap:wrap;gap:8px}
/* Tablet: the CBT palette drops under the question instead of squeezing it. */
@media(max-width:1024px){.cbt{grid-template-columns:1fr}.palette{grid-template-columns:repeat(8,1fr)}}
/* Phone: one column throughout, a 2x2 metric grid and full-width palette taps. */
@media(max-width:700px){.grid2,.grid3{grid-template-columns:1fr}.kv{grid-template-columns:1fr 1fr}h1{font-size:1.6rem}.nav a.hidem{display:none}.palette{grid-template-columns:repeat(5,1fr)}.cbt{gap:10px}.topbar{padding:10px 0}.brand span{display:none}}
@media(max-width:420px){.kv{grid-template-columns:1fr}.palette{grid-template-columns:repeat(4,1fr)}.brand{font-size:.9rem}.btn{padding:10px 14px;min-height:44px}}
@media(hover:none){.pal{min-height:48px}}

/* ===== exam screen =====
   The clock and the palette are the two things a candidate must never lose,
   so both are pinned rather than left to scroll. */
.exam-bar{position:sticky;top:0;z-index:6;background:var(--bg);border-bottom:1px solid var(--border);padding:8px 0 0;margin:0 0 12px}
.exam-bar-inner{display:flex;align-items:center;justify-content:space-between;gap:10px;min-height:44px}
.exam-title{display:flex;flex-direction:column;min-width:0}
.exam-title b{color:#fff;font-size:.95rem;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.exam-clock{text-align:right;flex:none}
.exam-progress{height:3px;background:#1c1c1c;margin-top:8px}
.exam-progress i{display:block;height:100%;background:var(--cyan);width:0;transition:width .2s ease}
.exam-bar.complete .exam-progress i{background:var(--ok)}
.exam-bar .timer{font-size:1.15rem;line-height:1.1}
.timer.urgent{color:var(--amber)}
.timer.critical{color:var(--bad)}

.cbt-side h2{margin-top:0}
.legend{list-style:none;display:flex;flex-wrap:wrap;gap:10px;margin:10px 0;font-size:.7rem;color:var(--dim)}
.legend li{display:flex;align-items:center;gap:5px}
.legend .sw{width:9px;height:9px;display:inline-block;border:1px solid var(--edge)}
.legend .sw.ans{background:#12301f;border-color:var(--ok)}
.legend .sw.rev{background:#2a1f05;border-color:var(--amber)}
.legend .sw.skip{background:var(--panel)}
.cbt-count{margin:0 0 10px;font-variant-numeric:tabular-nums}
.btn.block{display:block;width:100%;margin-top:8px}
.cbt-side [data-close-palette]{display:none}
button.pal-fab{display:none}
.pane-head{display:flex;justify-content:space-between;align-items:baseline;gap:10px;flex-wrap:wrap;font-size:.78rem}
.stem{margin:10px 0 6px;color:#fff;font-size:1rem;line-height:1.5}
.meta-line{margin-bottom:10px}
.opt-actions{display:flex;gap:8px;flex-wrap:wrap;margin-top:14px}
.opt-actions .btn{flex:1 1 auto;min-width:120px}

/* The palette is a drawer under the question: it was a wall of tiles that pushed
   the submit button off a phone screen. */
@media(max-width:1024px){
  /* A translated-off drawer is still in the tab order, so it is also hidden from
     assistive tech and hit testing while closed. */
  .cbt-side{position:fixed;left:0;right:0;bottom:0;background:var(--panel);border-top:1px solid var(--edge);padding:14px 16px calc(68px + env(safe-area-inset-bottom));max-height:78vh;overflow-y:auto;transform:translateY(100%);visibility:hidden;transition:transform .2s ease,visibility .2s;z-index:31}
  .cbt-side.open{transform:translateY(0);visibility:visible}
  .cbt-side h2{margin-top:0}
  /* The button that opens the drawer cannot live inside the drawer, so it floats
     above the tab bar where a thumb reaches it while reading a question. */
  /* It sits above the tab bar, so the page reserves that strip; without it the
     button lands on top of the last line of text. */
  button.pal-fab{
    display:flex;position:fixed;right:14px;z-index:25;
    bottom:calc(60px + env(safe-area-inset-bottom));
    margin:0;min-height:48px;padding:12px 16px;
    background:var(--panel);border:1px solid var(--cyan);color:var(--cyan);
  }
  button.pal-fab[aria-expanded=true]{
    /* While the drawer is open the button is redundant, so it leaves the
       submit row entirely rather than covering it. */
    display:none;
  }
  /* The drawer keeps its own close control at the top. */
  .cbt-side [data-close-palette]{display:block}
  .palette{grid-template-columns:repeat(6,1fr)}
  /* Room for the drawer so the last option row is never hidden behind it. */
  .cbt{padding-bottom:76px}
}

/* Phone: a smaller type step, tighter gaps, and touch-sized controls throughout. */
@media(max-width:700px){
  body{font-size:15px;padding:0 14px 72px}
  h1{font-size:1.55rem}
  h2{font-size:.7rem;margin:22px 0 10px}
  .exam-bar{padding-top:6px}
  .exam-title b{font-size:.85rem}
  .exam-bar .timer{font-size:1.35rem}
  .pane-head{font-size:.75rem}
  .stem{font-size:1.02rem;line-height:1.55}
  .opt-actions .btn{min-width:0;flex:1 1 44%;padding:12px 10px;min-height:48px}
  .palette{grid-template-columns:repeat(5,1fr);gap:8px}
  .pal{min-height:48px;font-size:.8rem}
  .kv .card b{font-size:1.3rem}
  /* Every control on the exam screen gets a thumb-sized target. */
  .btn{padding:11px 14px;min-height:44px}
  .opt{padding:12px 12px;min-height:48px}
  table{font-size:.78rem}
  /* A data table cannot shrink to a phone, so it scrolls inside its own box
     instead of pushing the whole page sideways. */
  .table-wrap{overflow-x:auto;-webkit-overflow-scrolling:touch;margin:0 -14px;padding:0 14px}
}

@media(max-width:420px){
  .palette{grid-template-columns:repeat(4,1fr)}
  .opt-actions .btn{flex:1 1 100%}
}

/* Tablet: the palette drops under the question, so it needs the same drawer
   treatment as a phone but with room for a wider grid. */
@media(max-width:1024px) and (min-width:701px){
  .cbt{padding-bottom:0}
  .cbt-side{max-height:70vh}
}

/* ===== phone navigation =====
   The desktop link row has nowhere to go under 700px. Rather than hiding it,
   the primary destinations move to a fixed bottom bar within thumb reach. */
.tabbar{display:none}
@media(max-width:700px){
  .tabbar{
    display:grid;grid-auto-flow:column;grid-auto-columns:1fr;
    position:fixed;left:0;right:0;bottom:0;z-index:30;
    background:var(--panel);border-top:1px solid var(--edge);
    padding-bottom:env(safe-area-inset-bottom);
  }
  .tabbar a{
    display:flex;align-items:center;justify-content:center;text-align:center;
    min-height:52px;padding:6px 4px;font-size:.72rem;color:var(--muted);
    border-right:1px solid var(--border);text-decoration:none;line-height:1.3;
  }
  .tabbar a:last-child{border-right:0}
  .tabbar a:active{background:#1c1c1c;color:#fff}
  .tabbar a:hover{text-decoration:none;color:#fff}
  /* The bar is fixed, so the page reserves its height or the last row sits under it. */
  body{padding-bottom:calc(72px + env(safe-area-inset-bottom))}
  /* Clear the floating palette button in the exam view only. */
  body.exam{padding-bottom:calc(122px + env(safe-area-inset-bottom))}
  footer{margin-top:32px}
}
@media(min-width:701px){body{padding-bottom:64px}}

/* ===== tap targets =====
   Measured at 35px on a pointer device and 13px on the chapter checkboxes,
   both below the 44px minimum. Padding fixes the hit area without making the
   control look heavy. */
.btn,a.btn{min-height:44px;padding:12px 18px;display:inline-flex;align-items:center;justify-content:center}
button.btn{line-height:1.2}
input[type=text],input[type=email],input[type=number],select{min-height:44px;padding:12px}
/* The native checkbox is small by design, so the label around it carries the target. */
.chk{min-height:44px}
.chk input[type=checkbox]{width:20px;height:20px;margin-top:2px;flex:none}
.opt{min-height:44px}
.opt input[type=radio]{width:20px;height:20px;flex:none}

/* ===== builder: subtopic picker =====
   Chapters are the primary unit; subtopics expand inside them. */
.subject-section{margin-bottom:20px}
.subject-label{font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;margin:0 0 8px}
.chapter-group{margin-bottom:8px}
.chapter-hd{display:flex;align-items:center;min-height:44px;background:var(--panel);padding:10px 12px;border:1px solid var(--border)}
.chapter-hd b{color:#fff}
.subtopic-list{padding:4px 12px 4px 32px;border:1px solid var(--border);border-top:0;display:none}
.chapter-group.expanded .subtopic-list{display:block}
.sub-chk{min-height:38px;padding:4px 0}
.settings-sticky{position:sticky;top:72px}
.picker-col,.settings-col{min-width:0}
.build-note{font-variant-numeric:tabular-nums}
.all-subj input[type=checkbox]{accent-color:var(--cyan)}
@media(max-width:700px){
  .settings-sticky{position:static}
  .chapter-hd{background:none;padding:10px 0}
  .subtopic-list{padding:4px 0 4px 20px}
}

/* ===== per-subject timers on exam screen =====
   Each strip shows for its subject window and hides when that window closes. */
.subj-timer-bar{display:flex;gap:12px;flex-wrap:wrap;margin-bottom:8px}
.subj-timer{display:flex;align-items:center;gap:8px;padding:6px 12px;background:var(--panel);border:1px solid var(--border);font-size:.8rem}
.subj-timer b{color:#fff;min-width:5ch;font-variant-numeric:tabular-nums}
.subj-timer.active{border-color:var(--cyan)}
.subj-timer.warn{border-color:var(--amber)}
.subj-timer.done{opacity:.4;text-decoration:line-through}