/* Layout: one drafting sheet on a ruled grid. A title-block strip across the top carries
   the sheet number (the question) and the clock; the drawing area below holds the work. */
:root {
  --paper: #EDF2F9;
  --sheet: #FFFFFF;
  --ink: #0F2F5F;
  --ink-2: #48628C;
  --rule: #C2D1E7;
  --grid: rgba(15, 47, 95, .065);
  --accent: #F5B800;
  --on-accent: #17223B;
  --mark: #FFF1BF;
  --pick: #0F2F5F;
  --good: #17754A;
  --good-bg: #E3F4EB;
  --bad: #B23A2E;
  --bad-bg: #FBE8E5;
  --display: "Barlow Condensed", "Arial Narrow", "Helvetica Neue", Arial, sans-serif;
  --body: "IBM Plex Sans", "Segoe UI", system-ui, -apple-system, Helvetica, Arial, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0A2750; --sheet: #0F3466; --ink: #EDF3FC; --ink-2: #A9BFE0; --rule: #37598F;
    --grid: rgba(255, 255, 255, .05); --accent: #FFC629; --on-accent: #14213D; --mark: #1D4A88; --pick: #FFC629;
    --good: #72DFA9; --good-bg: #114437; --bad: #FFA092; --bad-bg: #572932;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0A2750; --sheet: #0F3466; --ink: #EDF3FC; --ink-2: #A9BFE0; --rule: #37598F;
  --grid: rgba(255, 255, 255, .05); --accent: #FFC629; --on-accent: #14213D; --mark: #1D4A88; --pick: #FFC629;
  --good: #72DFA9; --good-bg: #114437; --bad: #FFA092; --bad-bg: #572932;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
body {
  background-color: var(--paper);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
  color: var(--ink);
  font: 400 1.0625rem/1.55 var(--body);
  padding-inline: 16px;
  padding-block: 20px 48px;
}
.sheet {
  max-width: 46rem;
  margin-inline: auto;
  background: var(--sheet);
  border: 1.5px solid var(--ink);
}
.sheet.wide { max-width: 68rem; }

/* title block */
.tb { display: grid; grid-template-columns: 1fr auto auto; border-bottom: 1.5px solid var(--ink); background: var(--sheet); }
.tb > div { padding: 8px 14px; border-left: 1px solid var(--rule); min-width: 0; display: flex; flex-direction: column; justify-content: center; }
.tb > div:first-child { border-left: 0; }
.tb .clock { text-align: right; }
.tb.run { grid-template-columns: auto 1fr auto auto; position: sticky; top: env(safe-area-inset-top, 0px); z-index: 5; }
@media (max-width: 39.99rem) {
  .tb.run { grid-template-columns: 1fr auto auto; }
  .tb.run .brand { display: none; }
  .tb.run .brand + div { border-left: 0; }
  .tb.run > div { padding: 7px 10px; }
  .tb.run .val { font-size: 1.0625rem; line-height: 1.08; }
  .tb.run .clock .val { font-size: 1.375rem; }
}
.lbl { font: 500 .6875rem/1.3 var(--mono); letter-spacing: .09em; text-transform: uppercase; color: var(--ink-2); }
.val { font: 700 1.25rem/1.15 var(--display); letter-spacing: .03em; text-transform: uppercase; }
.brand .val { font-size: 1.5rem; font-weight: 800; }
.tb .clock .val { font: 500 1.5rem/1.15 var(--mono); letter-spacing: 0; font-variant-numeric: tabular-nums; }
.clock.low .val { color: var(--bad); }

.area { padding: 22px 18px 26px; display: flex; flex-direction: column; gap: 20px; }
@media (min-width: 40rem) { .area { padding: 30px 34px 36px; gap: 24px; } }

h1, h2, h3 { margin: 0; text-wrap: balance; }
h1 { font: 800 clamp(2.1rem, 7.2vw, 3.4rem)/.98 var(--display); letter-spacing: .005em; text-transform: uppercase; }
h2 { font: 700 1.75rem/1.05 var(--display); letter-spacing: .02em; text-transform: uppercase; }
h3 { font: 600 1.0625rem/1.3 var(--body); }
h1:focus, h2:focus { outline: none; }
p { margin: 0; max-width: 62ch; }
.lead { font-size: 1.1875rem; color: var(--ink); }
.muted { color: var(--ink-2); }
.small { font-size: .9375rem; }
a { color: inherit; text-underline-offset: 3px; }
button, a { -webkit-tap-highlight-color: transparent; }
a:focus-visible, button:focus-visible, summary:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

/* schedule table */
.tablewrap { overflow-x: auto; }
table.sched { border-collapse: collapse; width: 100%; font-variant-numeric: tabular-nums; }
.sched th, .sched td { border: 1px solid var(--rule); padding: 9px 12px; text-align: left; }
.sched thead th { font: 500 .6875rem/1.3 var(--mono); letter-spacing: .09em; text-transform: uppercase; color: var(--ink-2); }
.sched td.n, .sched th.n { text-align: right; font-family: var(--mono); }

ul.rules { margin: 0; padding: 0; list-style: none; display: grid; gap: 10px; }
ul.rules li { display: grid; grid-template-columns: 1.75rem 1fr; gap: 10px; align-items: start; }
ul.rules .k { font: 500 .75rem/1.75rem var(--mono); width: 1.75rem; height: 1.75rem; text-align: center; border: 1px solid var(--ink); }

.btn {
  font: 700 1.25rem/1 var(--display); letter-spacing: .05em; text-transform: uppercase;
  padding: 15px 22px; border: 1.5px solid var(--ink); background: var(--sheet); color: var(--ink);
  cursor: pointer; border-radius: 0; text-decoration: none; display: inline-flex; align-items: center; justify-content: center; gap: 10px; min-height: 52px;
}
.btn.primary { background: var(--accent); color: var(--on-accent); border-color: var(--on-accent); }
.btn:hover { filter: brightness(.96); }
.btn[disabled] { opacity: .45; cursor: default; }
.row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.row.split { justify-content: space-between; }

/* question */
.qnav { display: flex; flex-wrap: wrap; gap: 6px; position: relative; }
/* phones: the question numbers become one row that scrolls sideways, so the question itself starts near the top */
@media (max-width: 39.99rem) {
  .qnav { flex-wrap: nowrap; overflow-x: auto; padding: 4px 4px 10px; margin: -4px -4px 0; scrollbar-width: thin; overscroll-behavior-x: contain; }
  .qnav button { flex: 0 0 auto; }
}
.qnav button {
  width: 2.5rem; height: 2.5rem; border: 1px solid var(--ink); background: var(--sheet); color: var(--ink);
  font: 500 .9375rem/1 var(--mono); cursor: pointer; border-radius: 0; position: relative;
}
.qnav button.done { background: var(--ink); color: var(--sheet); }
.qnav button.cur { box-shadow: 0 0 0 3px var(--accent); }
.stem { font-size: 1.1875rem; line-height: 1.5; max-width: 60ch; }
.eq { font-size: 1.3em; white-space: nowrap; }
.stem .eq { display: inline-block; margin: 0 .15em; }
.seq { display: block; font: 500 1.6rem/1.3 var(--mono); margin-top: 12px; letter-spacing: .02em; }
i { font-style: italic; }
sup { font-size: .65em; line-height: 0; }
.choices { display: grid; gap: 10px; grid-template-columns: 1fr; }
@media (min-width: 34rem) { .choices.math { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.choice {
  display: grid; grid-template-columns: 2.5rem 1fr; gap: 14px; align-items: center; text-align: left;
  padding: 11px 14px 11px 11px; border: 1px solid var(--ink); background: var(--sheet); color: var(--ink);
  font: 400 1.0625rem/1.4 var(--body); cursor: pointer; border-radius: 0; min-height: 60px; min-width: 0;
}
.choices.math .choice { font-size: 1.25rem; }
.choice .ltr { width: 2.5rem; height: 2.5rem; display: grid; place-items: center; border: 1px solid var(--ink); font: 500 1rem/1 var(--mono); }
.choice[aria-checked="true"] { background: var(--mark); box-shadow: inset 0 0 0 2px var(--pick); }
.choice[aria-checked="true"] .ltr { background: var(--accent); color: var(--on-accent); border-color: var(--on-accent); }
.choice > span:last-child { min-width: 0; overflow-wrap: anywhere; }

.figure { border: 1px solid var(--rule); padding: 10px; max-width: 22rem; }
.figure svg { display: block; width: 100%; height: auto; }
.xy { border-collapse: collapse; font: 500 1.125rem/1 var(--mono); font-variant-numeric: tabular-nums; }
.xy th, .xy td { border: 1px solid var(--ink); padding: 10px 16px; text-align: center; }
.xy th { font-family: var(--body); font-style: italic; font-weight: 500; background: var(--mark); }

.confirm { border: 1.5px solid var(--ink); background: var(--mark); padding: 16px; display: flex; flex-direction: column; gap: 12px; }

/* reading layout */
.read { display: grid; gap: 24px; grid-template-columns: 1fr; }
@media (min-width: 60rem) {
  .read { grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr); gap: 36px; align-items: start; }
  .read .passage { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 78px); max-height: calc(100vh - 100px); overflow: auto; }
}
.passage { border-left: 3px solid var(--ink); padding: 2px 0 2px 16px; display: flex; flex-direction: column; gap: 12px; }
.passage p { max-width: 64ch; }
.qcol { display: flex; flex-direction: column; gap: 20px; min-width: 0; scroll-margin-top: 84px; }

/* results */
.score { display: flex; flex-wrap: wrap; align-items: flex-end; gap: 8px 22px; }
.score .big { font: 800 clamp(4rem, 17vw, 6.5rem)/.82 var(--display); letter-spacing: -.01em; }
.score .of { font: 700 1.75rem/1 var(--display); text-transform: uppercase; letter-spacing: .03em; color: var(--ink-2); padding-bottom: 6px; }
.bars { display: grid; gap: 14px; }
.bar { display: grid; gap: 6px; }
.bar .top { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.bar .track { display: grid; grid-auto-flow: column; grid-auto-columns: 1fr; gap: 4px; }
.bar .seg { height: 14px; border: 1px solid var(--ink); }
.bar .seg.on { background: var(--ink); }
.note { border: 1px solid var(--rule); padding: 14px 16px; display: flex; flex-direction: column; gap: 8px; }
.work { margin: 0; padding: 0; list-style: none; display: grid; gap: 12px; }
.work li { border-left: 3px solid var(--bad); padding-left: 14px; display: flex; flex-direction: column; gap: 3px; }
details.rev { border: 1px solid var(--rule); }
details.rev + details.rev { border-top: 0; }
details.rev summary { cursor: pointer; padding: 12px 14px; display: grid; grid-template-columns: auto 1fr auto; gap: 12px; align-items: center; list-style: none; }
details.rev summary::-webkit-details-marker { display: none; }
.pill { font: 500 .6875rem/1 var(--mono); letter-spacing: .08em; text-transform: uppercase; padding: 6px 8px; border: 1px solid currentColor; white-space: nowrap; }
.pill.ok { color: var(--good); background: var(--good-bg); }
.pill.no { color: var(--bad); background: var(--bad-bg); }
details.rev .body { padding: 4px 14px 16px; display: flex; flex-direction: column; gap: 12px; border-top: 1px solid var(--rule); }
details.rev .body .stem { font-size: 1.0625rem; padding-top: 10px; }
.ans { display: grid; gap: 6px; }
.ans div { display: grid; grid-template-columns: 7.5rem 1fr; gap: 10px; }
.ans .t { font: 500 .6875rem/1.9 var(--mono); letter-spacing: .08em; text-transform: uppercase; color: var(--ink-2); }
details.psg summary { cursor: pointer; font: 500 .75rem/1.6 var(--mono); letter-spacing: .08em; text-transform: uppercase; color: var(--ink-2); }
details.psg .passage { margin-top: 10px; }
.cta { border: 1.5px solid var(--ink); padding: 20px 18px; display: flex; flex-direction: column; gap: 14px; background-image: repeating-linear-gradient(135deg, var(--grid) 0 2px, transparent 2px 10px); }
.foot { max-width: 46rem; margin: 18px auto 0; color: var(--ink-2); font-size: .875rem; }
.sheet.wide + .foot { max-width: 68rem; }
.kbd { display: none; }
@media (hover: hover) and (min-width: 60rem) { .kbd { display: block; } }
@media (prefers-reduced-motion: no-preference) { .choice, .qnav button, .btn { transition: background-color .12s ease, box-shadow .12s ease; } }