@font-face { font-family: "Barlow SC"; src: url("fonts/barlow-semi-condensed-700.woff2") format("woff2"); font-weight: 700; font-style: normal; font-display: swap; }

:root {
  --bg: #f4f5f7;
  --paper: #ffffff;
  --ink: #15171c;
  --muted: #4d5361;
  --line: #cdd1d9;
  --rule: #e4e7ec;
  --accent: #1f3fbf;        /* ballpoint blue */
  --accent-ink: #ffffff;
  --accent-soft: #e6ebfb;
  --pen: #c42b1c;           /* grader's red */
  --pen-soft: #fbe7e4;
  --ok: #1c6b3a;
  --ok-soft: #e1f1e6;
  --head: "Barlow SC", "Arial Narrow", "Roboto Condensed", system-ui, sans-serif;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --serif: "Times New Roman", Tinos, "Liberation Serif", Times, serif;
  --r: 6px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #11141b; --paper: #191d26; --ink: #e9ebf0; --muted: #a8afbd; --line: #343a48; --rule: #262b36;
    --accent: #8ea6ff; --accent-ink: #0d1020; --accent-soft: #232b48; --pen: #ff8a7a; --pen-soft: #3a1f1c; --ok: #7fd49a; --ok-soft: #1b3324;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 17px/1.55 var(--sans); }
.wrap { max-width: 820px; margin: 0 auto; padding: 0 16px; }
a { color: var(--accent); }
.skip { position: absolute; left: -999px; top: 8px; background: var(--paper); padding: 8px 12px; z-index: 10; }
.skip:focus { left: 8px; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
h1, h2 { font-family: var(--head); font-weight: 700; line-height: 1.12; letter-spacing: 0.005em; }
h1 { font-size: clamp(1.9rem, 6vw, 2.7rem); margin: 22px 0 6px; }
h2 { font-size: 1.55rem; margin: 30px 0 10px; }
.lede { margin: 0 0 16px; color: var(--muted); max-width: 62ch; }

/* level switch */
.levels { display: grid; grid-template-columns: 1fr 1fr; gap: 0; border: 2px solid var(--ink); border-radius: var(--r); overflow: hidden; max-width: 520px; }
.lvl { min-height: 52px; border: 0; background: var(--paper); color: var(--ink); font: 700 1.05rem var(--head); cursor: pointer; padding: 6px 8px; line-height: 1.15; }
.lvl small { display: block; font: 400 0.82rem var(--sans); color: var(--muted); }
.lvl + .lvl { border-left: 2px solid var(--ink); }
.lvl[aria-checked="true"] { background: var(--ink); color: var(--bg); }
.lvl[aria-checked="true"] small { color: var(--bg); opacity: 0.85; }

/* the test card */
.card { background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); padding: 16px; margin-top: 14px; }
.test-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap; }
.test-id { margin: 0; font: 700 1.35rem var(--head); }
.code { font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace; letter-spacing: 0.08em; font-size: 0.95em; }
.code .ver { font-family: var(--head); letter-spacing: 0; font-size: 1.05em; }
.peek { list-style: none; margin: 12px 0 4px; padding: 10px 0 0; border-top: 1px solid var(--rule); font-family: var(--serif); font-size: 1.12rem; columns: 2 220px; column-gap: 28px; }
.peek li { padding: 3px 0; break-inside: avoid; }
.peek .n, .problems .n, .preview-list .n, .ex-list .n { display: inline-block; min-width: 3.1em; color: var(--muted); font-variant-numeric: tabular-nums; }
.peek .more-line { color: var(--muted); font: 0.92rem var(--sans); }
.actions { display: flex; flex-wrap: wrap; gap: 10px; margin: 14px 0 6px; }
.btn { min-height: 46px; padding: 10px 18px; border-radius: var(--r); border: 2px solid var(--ink); background: var(--paper); color: var(--ink); font: 700 1.02rem var(--head); letter-spacing: 0.01em; cursor: pointer; }
.btn:hover { background: var(--accent-soft); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.primary:hover { filter: brightness(1.08); }
.btn.ghost { border-color: var(--line); }
.btn.small { min-height: 44px; padding: 6px 12px; font-size: 0.98rem; }
.btn:disabled { opacity: 0.5; cursor: default; }
.link { background: none; border: 0; padding: 10px 2px; min-height: 44px; color: var(--accent); text-decoration: underline; font: inherit; cursor: pointer; }
details.more { border-top: 1px solid var(--rule); margin-top: 10px; }
details.more > summary { cursor: pointer; padding: 11px 0; min-height: 44px; font-weight: 600; }
.opt-grid { display: flex; flex-wrap: wrap; gap: 12px 20px; align-items: center; }
label { font-weight: 600; }
select, input[type="text"], input:not([type]) { font: 16px var(--sans); color: var(--ink); background: var(--paper); border: 1px solid var(--muted); border-radius: var(--r); min-height: 44px; padding: 6px 8px; }
.opt-grid label, .drill-setup label { display: flex; align-items: center; gap: 8px; }
.check input { width: 22px; height: 22px; accent-color: var(--accent); }
.hint { margin: 6px 0; color: var(--muted); font-size: 0.95rem; }
.share-row { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin: 10px 0 12px; }
.open-code { display: flex; align-items: center; gap: 8px; }
.open-code input { width: 6.5em; text-transform: uppercase; font-family: ui-monospace, Menlo, Consolas, monospace; }
.note { padding: 10px 12px; border-left: 4px solid var(--accent); background: var(--accent-soft); border-radius: 0 var(--r) var(--r) 0; margin: 10px 0; }
.note.warn { border-left-color: var(--pen); background: var(--pen-soft); }
.preview-list { list-style: none; padding: 0; margin: 0 0 12px; font-family: var(--serif); font-size: 1.05rem; }
.preview-list li { padding: 5px 0; border-bottom: 1px solid var(--rule); }
.preview-list .k { color: var(--muted); font: 0.9rem var(--sans); white-space: nowrap; }

/* math bits */
.fr { display: inline-flex; flex-direction: column; vertical-align: middle; text-align: center; font-size: 0.82em; line-height: 1.08; margin: 0 0.12em; }
.fr > span:first-child { border-bottom: 1px solid currentColor; padding: 0 0.15em; }
.nw { white-space: nowrap; }
.rad { border-top: 1px solid currentColor; padding: 0 0.12em; margin-left: 0.04em; }
.idx { font-size: 0.6em; vertical-align: 0.85em; margin-right: -0.3em; }
sup { font-size: 0.7em; line-height: 0; }

/* the on-screen test */
.sheet { background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); margin-top: 14px; padding: 0 16px 16px; }
.timer-bar { position: sticky; top: 0; z-index: 5; display: flex; align-items: center; gap: 12px; flex-wrap: wrap; background: var(--paper); border-bottom: 2px solid var(--ink); padding: 10px 0; margin: 0 0 4px; }
.clock { font: 700 2rem/1 var(--head); font-variant-numeric: tabular-nums; min-width: 3.2em; }
.clock.low { color: var(--pen); }
.answered { color: var(--muted); }
.bar-btns { margin-left: auto; display: flex; gap: 8px; }
.sheet-title { font-size: 1.2rem; margin: 12px 0 6px; }
.problems { list-style: none; margin: 0; padding: 0; font-family: var(--serif); font-size: 1.15rem; max-width: 640px; } /* answer box near its problem on wide screens */
.problems li { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 10px; padding: 9px 0; border-bottom: 1px solid var(--rule); scroll-margin-top: 90px; }
.problems .qt { flex: 1 1 170px; min-width: 0; padding-left: 3.1em; text-indent: -3.1em; } /* wrapped lines start under the problem, not under its number */
.problems .qt * { text-indent: 0; }
.problems .ans { display: flex; align-items: center; gap: 6px; font-family: var(--sans); font-size: 1rem; }
.problems input { width: 8.5em; font: 18px var(--sans); font-variant-numeric: tabular-nums; }
.problems .ans { margin-left: auto; }
.problems .unit { color: var(--muted); }
.problems li.star .n { color: var(--ink); font-weight: 700; }
.mk { font: 0.95rem var(--sans); flex-basis: 100%; padding-left: 3.1em; }
.mk.right { color: var(--ok); }
.mk.wrong { color: var(--pen); }
li.is-wrong .n, li.is-skip .n { position: relative; color: var(--pen); }
li.is-wrong .n::after, li.is-skip .n::after { content: "×"; position: absolute; left: 0.55em; top: -0.42em; font: 700 1.55em/1 var(--sans); color: var(--pen); }
li.is-right input, li.is-wrong input, li.is-skip input { background: var(--bg); }
.paused { text-align: left; padding: 30px 0; }
.paused p { font-size: 1.15rem; margin: 0 0 12px; }
.result { padding: 12px 0 6px; }
.score-big { font: 700 3rem/1 var(--head); margin: 4px 0 6px; }
.score-line { margin: 0 0 6px; color: var(--muted); }
.sheet-foot { display: flex; flex-wrap: wrap; gap: 10px; padding-top: 14px; }

/* drill */
.drill { margin-top: 8px; }
.drill-setup { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.drill-setup .wide { flex: 1 1 100%; display: grid; grid-template-columns: 1fr; gap: 4px; }
.drill-setup .wide select { width: 100%; min-width: 0; }
.drill-run { background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); padding: 4px 16px 16px; margin-top: 12px; }
.drill-bar { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 6px; padding: 10px 0; border-bottom: 2px solid var(--ink); font-weight: 700; }
.drill-score { font-variant-numeric: tabular-nums; }

/* history */
.hist { list-style: none; padding: 0; margin: 0; }
.hist li { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 12px; padding: 8px 0; border-bottom: 1px solid var(--rule); }
.hist .what { flex: 1 1 220px; }
.hist .when { color: var(--muted); font-size: 0.92rem; }
.hist .sc { font-weight: 700; font-variant-numeric: tabular-nums; }
.hist-tools { margin: 6px 0; }

/* content */
.content { margin-top: 26px; max-width: 70ch; }
.example { margin: 0; background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); padding: 14px 16px; }
.ex-list { list-style: none; padding: 0; margin: 0 0 8px; font-family: var(--serif); font-size: 1.12rem; }
.ex-list li { padding: 4px 0; }
.blank { display: inline-block; width: 6em; border-bottom: 1px solid currentColor; vertical-align: -2px; }
figcaption { color: var(--muted); font-size: 0.97rem; }
.faq details { border-bottom: 1px solid var(--rule); }
.faq summary { cursor: pointer; padding: 12px 0; min-height: 44px; font-weight: 600; }
.faq p { margin: 0 0 14px; }
.sources { font-size: 0.93rem; color: var(--muted); margin-top: 22px; }

footer { margin-top: 40px; border-top: 1px solid var(--line); padding: 18px 0 30px; color: var(--muted); font-size: 0.93rem; }
.indep { margin: 0 0 10px; }
.sb-more { line-height: 1.9; }
.sb-more a { color: var(--muted); }
.sb-privacy, .sb-credit { margin: 6px 0; }

/* answer keys on touch screens (app.js) */
.keys { flex-basis: 100%; padding: 4px 0 2px; font-family: var(--sans); }
.krow { display: flex; flex-wrap: wrap; gap: 6px; }
.kgrid { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 6px; }
.kgrid .kk { min-width: 0; } /* six columns fit a 320 px phone */
@media (max-width: 380px) { .krow { gap: 4px; } .krow .kk { min-width: 0; padding: 0 2px; } .kgrid { gap: 4px; } }
.kk { min-height: 46px; min-width: 48px; border: 1px solid var(--line); border-radius: var(--r); background: var(--bg); color: var(--ink);
  font: 600 1.15rem var(--sans); touch-action: manipulation; -webkit-user-select: none; user-select: none; cursor: pointer; }
.krow .kk { flex: 1 1 0; }
.krow .kk[data-k="next"] { flex-grow: 1.5; }
.kk:active { background: var(--accent-soft); }
.kk { -webkit-tap-highlight-color: transparent; }
.kk[data-k=" "] { font-size: 0.85rem; }
.kk[data-k="next"] { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.kk[aria-pressed="true"] { border: 2px solid var(--accent); }
.kgrid .kk[data-k="next"] { grid-column: span 2; }
[hidden] { display: none !important; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap; }
.myv { display: flex; align-items: center; gap: 8px; }
.print-root { display: none; }
@media (prefers-reduced-motion: no-preference) { html { scroll-behavior: smooth; } }
@media (max-width: 520px) {
  .actions .btn { flex: 1 1 100%; }
  .problems input { width: 6.6em; }
  .problems li { padding: 7px 0; }
  .timer-bar { gap: 6px 8px; }
  .answered { font-size: 0.88rem; }
  .bar-btns .btn.small { padding: 6px 10px; }
  .clock { font-size: 1.7rem; min-width: 2.9em; }
}
@media (max-width: 380px) { /* 320 px phones: clock, count and both buttons on one line */
  .sheet { padding: 0 10px 12px; }
  .timer-bar { gap: 6px; }
  .clock { font-size: 1.5rem; min-width: 0; }
  .answered { font-size: 0.8rem; }
  .bar-btns { gap: 6px; }
  .bar-btns .btn.small { padding: 6px 8px; }
}

/* ===================== print: the test sheet and key ===================== */
@page { margin: 0.45in; }
@media print {
  body { background: #fff; color: #000; font: 11pt/1.3 var(--serif); }
  main, footer, .skip { display: none !important; }
  .print-root { display: block; }
  .ps-page { height: 9.85in; display: flex; flex-direction: column; break-after: page; overflow: hidden; }
  .ps-page:last-child { break-after: auto; }
  .ps-head { display: grid; grid-template-columns: 1fr auto; gap: 4pt 16pt; align-items: start; border-bottom: 1.5pt solid #000; padding-bottom: 6pt; }
  .ps-title { font: 700 14pt/1.15 var(--head); margin: 0; }
  .ps-sub { margin: 2pt 0 0; font: 10pt var(--sans); }
  .ps-num { font: 10pt var(--sans); margin: 0 0 6pt; }
  .ps-score { font: 10pt var(--sans); text-align: right; }
  .ps-score span { display: inline-block; width: 0.75in; border-bottom: 0.75pt solid #000; }
  .ps-dir { font: 9.5pt/1.35 var(--sans); margin: 6pt 0 4pt; }
  .ps-run { font: 9pt var(--sans); display: flex; justify-content: space-between; border-bottom: 0.75pt solid #000; padding-bottom: 3pt; }
  .ps-cols { flex: 1; display: grid; grid-template-columns: 1fr 1fr; column-gap: 0.3in; padding-top: 6pt; min-height: 0; }
  .ps-col { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; }
  .ps-col li { flex: 1 1 auto; display: flex; align-items: center; font-size: 11pt; line-height: 1.22; padding: 1pt 0; }
  .ps-col .n { flex: 0 0 0.42in; font-variant-numeric: tabular-nums; }
  .ps-col .qt { flex: 1; }
  .ps-col .bl { display: inline-block; min-width: 1.05in; border-bottom: 0.75pt solid #000; height: 1em; vertical-align: -2pt; margin: 0 2pt; }
  .ps-key { break-before: page; }
  .ps-key-title { font: 700 13pt var(--head); margin: 0 0 4pt; }
  .ps-key-grid { display: grid; grid-template-columns: repeat(4, 1fr); grid-auto-flow: column; grid-template-rows: repeat(20, auto); column-gap: 0.18in; border-top: 1.5pt solid #000; padding-top: 4pt; }
  .ps-key-grid div { display: flex; align-items: center; min-height: 0.4in; border-bottom: 0.5pt solid #999; font-size: 10.5pt; }
  .ps-key-grid .n { flex: 0 0 0.4in; }
  .ps-key-note { font: 9pt/1.35 var(--sans); margin-top: 8pt; }
  .ps-key-page { height: 9.85in; break-after: page; }
  .ps-key-page:last-child { break-after: auto; }
  .fr > span:first-child { border-bottom: 0.75pt solid #000; }
}