/* Sharp, monochrome, light-only. */
:root {
  --bg: #ffffff;
  --bg-2: #f4f4f4;
  --line: #000000;
  --hair: #d9d9d9;
  --text: #000000;
  --muted: #5c5c5c;
  --inv: #ffffff;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Consolas, monospace;
  color-scheme: light;
}

* { box-sizing: border-box; border-radius: 0 !important; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font: 15.5px/1.65 var(--sans);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--text); text-decoration: underline; text-underline-offset: 3px; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }
::selection { background: #000; color: #fff; }

.wrap { max-width: 980px; margin: 0 auto; padding: 0 16px; }

/* ---------- top bar ---------- */
.topbar { position: sticky; top: 0; z-index: 20; background: var(--bg); border-bottom: 2px solid var(--line); }
.topbar .wrap { display: flex; align-items: center; gap: 10px; height: 56px; }
.brand {
  font: 700 14px var(--mono); letter-spacing: .08em; text-transform: uppercase; color: var(--text);
  text-decoration: none; display: flex; align-items: center; gap: 10px;
}
.brand .dot { width: 12px; height: 12px; background: var(--text); }
.spacer { flex: 1; }
.btn {
  appearance: none; border: 1.5px solid var(--line); background: var(--bg); color: var(--text);
  font: 600 12.5px var(--mono); letter-spacing: .04em; text-transform: uppercase;
  padding: 7px 12px; cursor: pointer; text-decoration: none;
  display: inline-flex; align-items: center; gap: 6px;
}
.btn:hover { background: var(--text); color: var(--inv); text-decoration: none; }
.btn.primary { background: var(--text); color: var(--inv); }
.btn.primary:hover { background: var(--bg); color: var(--text); }
.btn[disabled] { opacity: .35; pointer-events: none; }

/* ---------- index ---------- */
.hero { padding: 56px 0 28px; border-bottom: 1px solid var(--hair); }
.hero h1 { font-size: clamp(30px, 6vw, 52px); line-height: 1.05; letter-spacing: -.035em; margin: 0 0 12px; font-weight: 800; }
.hero p { color: var(--muted); margin: 0; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); border: 2px solid var(--line); margin: 28px 0; }
.stat { padding: 16px 18px; border-right: 1px solid var(--line); }
.stat:last-child { border-right: 0; }
@media (max-width: 700px) { .stat { border-right: 0; border-bottom: 1px solid var(--line); } .stat:last-child { border-bottom: 0; } }
.stat .k { font: 600 11px var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: .1em; }
.stat .v { font-size: 30px; font-weight: 800; letter-spacing: -.03em; line-height: 1.2; margin-top: 4px; }
.bar { height: 6px; border: 1px solid var(--line); margin-top: 10px; }
.bar > i { display: block; height: 100%; background: var(--text); }

.section-h { display: flex; align-items: baseline; gap: 12px; margin: 40px 0 14px; }
.section-h h2 { font: 700 13px var(--mono); text-transform: uppercase; letter-spacing: .12em; margin: 0; }
.section-h span { color: var(--muted); font: 12px var(--mono); }

.grid52 { display: grid; grid-template-columns: repeat(13, 1fr); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
@media (max-width: 640px) { .grid52 { grid-template-columns: repeat(7, 1fr); } }
.cell {
  aspect-ratio: 1; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); background: var(--bg);
  display: grid; place-items: center; font: 600 12px var(--mono); color: #b0b0b0; position: relative; text-decoration: none;
}
.cell.pub { background: var(--text); color: var(--inv); }
.cell.pub:hover { background: var(--bg); color: var(--text); }
.cell.today { box-shadow: inset 0 0 0 3px var(--text); color: var(--text); }
.cell.pub.today { box-shadow: inset 0 0 0 3px var(--text), inset 0 0 0 5px var(--inv); color: var(--inv); }
.cell.scored::after { content: "✓"; position: absolute; top: 2px; right: 4px; font-size: 10px; }

.filters { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 14px; }
.chip {
  display: inline-flex; align-items: center; gap: 6px; font: 600 11px var(--mono);
  letter-spacing: .04em; text-transform: uppercase;
  padding: 3px 8px; border: 1px solid var(--line); background: var(--bg); color: var(--text); white-space: nowrap;
}
button.chip { cursor: pointer; }
button.chip.on, button.chip:hover { background: var(--text); color: var(--inv); }
.chip .sw { display: none; }

.days { border-top: 2px solid var(--line); margin-bottom: 64px; }
.daycard {
  display: grid; grid-template-columns: 72px 1fr auto; gap: 18px; align-items: center;
  border-bottom: 1px solid var(--line); padding: 18px 4px; color: var(--text); text-decoration: none;
}
.daycard:hover { background: var(--bg-2); text-decoration: none; }
.daycard .num { font: 800 28px var(--mono); letter-spacing: -.04em; line-height: 1; }
.daycard .num small { display: block; font: 500 11px var(--mono); color: var(--muted); letter-spacing: 0; margin-top: 6px; }
.daycard .t { font-weight: 700; }
.daycard .s { color: var(--muted); font-size: 13.5px; }
.daycard .meta { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.daycard .score { font: 700 14px var(--mono); text-align: right; }
.daycard .score.none { color: var(--muted); font-weight: 500; font-size: 12px; text-transform: uppercase; letter-spacing: .06em; }
@media (max-width: 640px) {
  .daycard { grid-template-columns: 52px 1fr; }
  .daycard .score { grid-column: 2; text-align: left; }
}
.empty { color: var(--muted); padding: 24px; text-align: center; border: 1px dashed var(--line); }

/* ---------- day page ---------- */
.dayhead { padding: 40px 0 8px; }
.eyebrow { font: 700 12px var(--mono); letter-spacing: .1em; text-transform: uppercase; }
.dayhead h1 { font-size: clamp(26px, 5vw, 42px); line-height: 1.08; letter-spacing: -.03em; margin: 10px 0 12px; font-weight: 800; }
.dayhead .sub { color: var(--muted); max-width: 70ch; }
.dayhead .meta { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 14px; }

.tabs {
  position: sticky; top: 56px; z-index: 15; background: var(--bg);
  display: flex; border-bottom: 2px solid var(--line); margin: 24px 0 0; overflow-x: auto;
}
.tab {
  appearance: none; background: none; border: 0; border-right: 1px solid var(--hair); color: var(--muted);
  font: 700 12.5px var(--mono); letter-spacing: .08em; text-transform: uppercase; padding: 13px 18px; cursor: pointer; white-space: nowrap;
}
.tab:hover { color: var(--text); }
.tab.on { background: var(--text); color: var(--inv); }
.tab .count { font: 500 11px var(--mono); margin-left: 6px; opacity: .7; }

.panel { display: none; padding: 8px 0 80px; }
.panel.on { display: block; }

.timer {
  position: sticky; top: 103px; z-index: 10; margin: 0 0 18px;
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  background: var(--bg); border-bottom: 1px solid var(--line); padding: 12px 0;
}
.timer .clock { font: 800 26px var(--mono); letter-spacing: .02em; min-width: 96px; }
.timer.low .clock { background: var(--text); color: var(--inv); padding: 0 8px; }
.timer .info { color: var(--muted); font: 12px var(--mono); text-transform: uppercase; letter-spacing: .06em; }

/* ---------- prose ---------- */
.prose { overflow-wrap: break-word; }
.prose h2 { font-size: 26px; letter-spacing: -.025em; margin: 40px 0 12px; font-weight: 800; }
.prose h3 {
  font: 700 13px var(--mono); text-transform: uppercase; letter-spacing: .12em;
  margin: 44px 0 14px; padding: 10px 0 0; border-top: 2px solid var(--line);
}
.prose h4 { font-size: 16px; margin: 26px 0 8px; font-weight: 700; }
.prose p, .prose ul, .prose ol { margin: 10px 0; }
.prose li { margin: 4px 0; }
.prose hr { border: 0; border-top: 1px solid var(--line); margin: 28px 0; }
.prose strong { font-weight: 700; }
.prose code { font: 13.2px var(--mono); background: var(--bg-2); padding: 1px 4px; }
.prose pre { background: var(--bg); border: 1px solid var(--line); border-left: 4px solid var(--line); padding: 14px 16px; overflow-x: auto; }
.prose pre code { background: none; padding: 0; font-size: 13.5px; line-height: 1.6; }
.prose table { border-collapse: collapse; width: 100%; font-size: 14px; display: block; overflow-x: auto; }
.prose th, .prose td { border: 1px solid var(--line); padding: 7px 10px; text-align: left; vertical-align: top; }
.prose th { background: var(--text); color: var(--inv); font: 700 12px var(--mono); text-transform: uppercase; letter-spacing: .06em; }
.prose th code { background: none; color: inherit; }
.prose blockquote { margin: 18px 0; padding: 14px 18px; border: 2px solid var(--line); background: var(--bg-2); }
.prose blockquote table { display: table; background: var(--bg); }

/* ---------- question cards ---------- */
.q { border: 2px solid var(--line); padding: 18px 20px; margin: 18px 0; scroll-margin-top: 180px; background: var(--bg); }
.q-head { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin: -18px -20px 14px; padding: 8px 12px; border-bottom: 1px solid var(--line); }
.q-num { font: 800 15px var(--mono); margin-right: 6px; }
.q-sub { color: var(--muted); font-size: 13px; margin-left: auto; }
.chip.t-MCQ { background: var(--bg); }
.chip.t-MSQ { background: var(--text); color: var(--inv); }
.chip.t-NAT { border-style: dashed; }
.q .opts { display: grid; margin: 14px 0 4px; border-top: 1px solid var(--line); }
.q .opt {
  display: flex; gap: 12px; align-items: center; padding: 8px 10px; border: 1px solid var(--line); border-top: 0;
  cursor: pointer; user-select: none;
}
.q .opt:hover { background: var(--bg-2); }
.q .opt.sel { background: var(--text); color: var(--inv); }
.q .opt.sel code { background: transparent; color: var(--inv); }
.q .opt .lbl { flex: none; width: 24px; height: 24px; display: grid; place-items: center; font: 800 12px var(--mono); border: 1px solid currentColor; }
.q .nat { margin-top: 14px; display: flex; gap: 10px; align-items: center; }
.q .nat input { font: 14px var(--mono); padding: 7px 10px; border: 1.5px solid var(--line); background: var(--bg); color: var(--text); width: 170px; outline: none; }
.q .nat input:focus { box-shadow: 3px 3px 0 var(--text); }
.q .nat span { color: var(--muted); font: 11px var(--mono); text-transform: uppercase; letter-spacing: .06em; }

.daynav { display: flex; justify-content: space-between; gap: 12px; padding: 24px 0 48px; border-top: 2px solid var(--line); }

footer { color: var(--muted); font: 11px var(--mono); text-transform: uppercase; letter-spacing: .08em; text-align: center; padding: 24px 0 40px; border-top: 1px solid var(--hair); }
.loading { color: var(--muted); padding: 48px 0; text-align: center; font-family: var(--mono); }

/* ---------- syntax: monochrome via weight & tone ---------- */
.hljs-keyword, .hljs-type, .hljs-built_in, .hljs-literal { font-weight: 700; color: #000; }
.hljs-string, .hljs-char, .hljs-number { color: #444; }
.hljs-comment { color: #8a8a8a; font-style: italic; }
.hljs-meta, .hljs-meta .hljs-keyword { color: #6b6b6b; font-weight: 600; }
.hljs-title.function_, .hljs-title { text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 2px; }

/* show operators literally (no ligatures) */
code, pre, .q-num, .clock, .cell, .daycard .num, .eyebrow, .btn, .chip, .tab { font-variant-ligatures: none; font-feature-settings: "liga" 0, "calt" 0; }

@media print {
  .topbar, .tabs, .timer, .daynav, footer { display: none !important; }
  .panel { display: block !important; padding: 0; }
  .q { break-inside: avoid; }
}