/* Meter Reading Practice: a meter reader's route book. Cool slate ground like meter glass, white meter faces with
   black numerals and pointers, a dark band across the top of each question like a meter's name plate, and an amber
   accent (the color of a reader's handheld) for actions and question numbers. Black on white on paper: every dial
   reads without color, and the liter wheels are labeled as well as red. */
:root {
  --bg: #eef2f6;
  --paper: #ffffff;
  --ink: #17212e;
  --muted: #4a5666;
  --line: #ccd5df;
  --edge: #7a8797;
  --band: #23324a;
  --band-ink: #ffffff;
  --accent: #a54d00;
  --accent-ink: #ffffff;
  --accent-soft: #fbeadb;
  --info: #1f5d9e;
  --ok: #17693c;
  --ok-soft: #dcefe3;
  --close: #7a5200;
  --close-soft: #f6ecd3;
  --bad: #a3241d;
  --bad-soft: #f8e0dd;
  --focus: #1b5fd0;
  --face: #ffffff;
  --dial: #17212e;
  --red: #b3261e;
  --red-soft: #fdeceb;
  --head: "Avenir Next", Avenir, "Segoe UI", "Trebuchet MS", system-ui, sans-serif;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, "DejaVu Sans Mono", monospace;
  --r: 8px;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #11161d;
    --paper: #19212b;
    --ink: #e4eaf1;
    --muted: #a3afbd;
    --line: #2c3745;
    --edge: #5d6b7c;
    --band: #2c3d57;
    --band-ink: #f2f6fb;
    --accent: #f0a35c;
    --accent-ink: #261200;
    --accent-soft: #3a2918;
    --info: #8fbdf0;
    --ok: #8adca6;
    --ok-soft: #14301f;
    --close: #f0c56b;
    --close-soft: #352a12;
    --bad: #ff9c8f;
    --bad-soft: #3a1c18;
    --focus: #8ab8ff;
    --face: #f4f6f8;
    --dial: #111820;
    --red: #ff8a80;
    --red-soft: #3b1d1b;
  }
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 17px/1.55 var(--sans); }
.wrap { max-width: 1160px; margin: 0 auto; padding: 0 16px; }
a { color: var(--info); text-underline-offset: 2px; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--paper); padding: 8px 12px; z-index: 10; }
.skip:focus { left: 8px; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }
h1, h2, h3 { font-family: var(--head); line-height: 1.15; font-weight: 700; }
.hero { padding: 22px 0 12px; }
.hero h1 { font-size: clamp(30px, 6vw, 44px); margin: 0 0 6px; letter-spacing: -0.015em; }
.lede { margin: 0; max-width: 62ch; color: var(--muted); }

/* ---------- controls ---------- */
.tool { display: grid; gap: 14px; grid-template-columns: 1fr; align-items: start; }
.setup { background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); padding: 12px 14px; }
.setgrid { display: grid; grid-template-columns: 1fr auto; gap: 10px 14px; align-items: end; }
.setgrid .span { grid-column: 1 / -1; }
fieldset { border: 0; margin: 0; padding: 0; min-width: 0; }
legend { font: 600 14px var(--sans); color: var(--muted); padding: 0; margin-bottom: 4px; }
.seg { display: grid; border: 1px solid var(--edge); border-radius: var(--r); overflow: hidden; }
.seg3 { grid-template-columns: 1fr 1fr 1fr; }
.sg { position: relative; display: block; min-width: 0; }
.sg + .sg { border-left: 1px solid var(--edge); }
.sg input { position: absolute; opacity: 0; inset: 0; margin: 0; cursor: pointer; }
.sg span { display: flex; align-items: center; justify-content: center; text-align: center; min-height: 44px; padding: 4px 6px; font-size: 15px; line-height: 1.15; }
.sg input:checked + span { background: var(--band); color: var(--band-ink); font-weight: 600; }
.sg input:focus-visible + span { outline: 3px solid var(--focus); outline-offset: -3px; }
.tdet { margin-top: 6px; }
.tdet summary, .rules summary { cursor: pointer; font-weight: 600; min-height: 44px; padding: 10px 0; }
.tsum { font-weight: 400; color: var(--muted); font-size: 15px; }
.toggles { display: grid; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); gap: 6px; padding-top: 4px; }
.tg { display: flex; gap: 8px; align-items: flex-start; padding: 8px; border: 1px solid var(--line); border-radius: var(--r); cursor: pointer; min-height: 44px; }
.tg input { width: 20px; height: 20px; margin: 2px 0 0; accent-color: var(--accent); flex: none; }
.tg b { display: block; font-weight: 600; font-size: 15.5px; }
.tg small { display: block; color: var(--muted); font-size: 14px; line-height: 1.3; }
.tg.off { opacity: 0.55; }
.inline { display: inline-flex; align-items: center; gap: 8px; font-weight: 600; }
select, input { font: inherit; font-size: 16px; color: var(--ink); background: var(--paper); border: 1px solid var(--edge); border-radius: 6px; min-height: 44px; padding: 6px 10px; }
.btn { font: 600 16px var(--sans); min-height: 44px; padding: 8px 16px; border-radius: 6px; border: 1px solid var(--edge); background: var(--paper); color: var(--ink); cursor: pointer; }
.btn:hover { border-color: var(--ink); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.small { min-height: 40px; padding: 6px 14px; font-size: 15px; }
.link { font: inherit; background: none; border: 0; color: var(--info); text-decoration: underline; text-underline-offset: 2px; cursor: pointer; min-height: 44px; padding: 0 4px; }

/* ---------- reading rules ---------- */
.rules { background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); padding: 4px 14px 10px; align-self: start; }
.why { margin: 2px 0 8px; font-size: 15px; line-height: 1.45; }
.rl { margin: 4px 0 0; padding-left: 20px; font-size: 15px; line-height: 1.45; }
.rl li { margin: 0 0 6px; }
.rl .src { display: block; color: var(--muted); font-size: 13.5px; }

/* ---------- the sheet ---------- */
.note { margin: 0 0 10px; padding: 10px 12px; border-left: 4px solid var(--bad); background: var(--bad-soft); border-radius: 6px; font-size: 15.5px; }
.note.info { border-color: var(--info); background: var(--paper); }
.sheet:focus { outline: none; }
.sheet-head { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 4px 14px; }
.sheet-head h2 { font-size: 26px; margin: 6px 0 0; }
.code { font-family: var(--mono); letter-spacing: 0.06em; }
.score { margin: 0; color: var(--muted); font-size: 15px; }
.sline { margin: 2px 0 10px; color: var(--muted); font-size: 14.5px; }
.qs { list-style: none; margin: 0; padding: 0; display: grid; gap: 16px; }
.q { background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); overflow: hidden; min-width: 0; }
.q h3 { margin: 0; background: var(--band); color: var(--band-ink); font-size: 19px; padding: 9px 14px; display: flex; align-items: center; gap: 10px; }
.qn { display: inline-grid; place-items: center; min-width: 28px; height: 28px; border-radius: 14px; background: var(--accent); color: var(--accent-ink); font-size: 15px; }
.scen { margin: 10px 14px 6px; max-width: 75ch; }
.figview { padding: 0 14px; min-width: 0; }
.meters { display: flex; flex-wrap: wrap; gap: 10px 18px; align-items: flex-start; }
.mwrap { min-width: 0; max-width: 100%; }
svg.meter { display: block; max-width: 100%; height: auto; }
.qparts { display: grid; grid-template-columns: 1fr; gap: 10px; padding: 8px 14px 14px; }
/* meter ink: the face stays white in dark mode, like a real meter behind its glass */
.frame { fill: var(--face); stroke: var(--edge); stroke-width: 1.5; }
.mtitle { fill: var(--dial); font: 700 11.5px var(--sans); letter-spacing: 0.12em; }
.cap { fill: var(--muted); font: italic 12.5px var(--sans); }
.face { fill: #fff; stroke: var(--dial); stroke-width: 1.8; }
.focus .face { stroke-width: 4; }
.tk { stroke: var(--dial); stroke-width: 1.2; }
.nm { fill: var(--dial); font: 700 13.5px var(--sans); }
.nm.sm { font-size: 10px; }
.ptr { fill: var(--dial); }
.hub { fill: #fff; stroke: var(--dial); stroke-width: 1.4; }
.arc { fill: none; stroke: var(--dial); stroke-width: 1.2; }
.ah { fill: var(--dial); }
.dlab { fill: var(--dial); font: 600 11px var(--sans); }
.dlab.sm { font-size: 10px; }
.test .face { stroke-dasharray: 3 2; }
.wh { fill: #fff; stroke: var(--dial); stroke-width: 1.6; }
.wh.red { stroke: #b3261e; fill: #fdeceb; stroke-width: 2.2; }
.wd { fill: var(--dial); font: 700 22px var(--mono); }
.wd.red, .grp.red { fill: #b3261e; }
.grp { fill: var(--dial); font: 600 12px var(--sans); }
.leak { stroke: var(--dial); stroke-width: 2.4; stroke-linecap: round; }
.kbox rect { fill: #fff; stroke: #a54d00; stroke-width: 1.6; }
.kd { fill: #7a3a00; font: 700 15px var(--sans); }
.kd.sm { font-size: 11px; }
.kd.wide { font-size: 14px; }
table.rates { border-collapse: collapse; margin: 8px 0 4px; font-size: 15px; font-variant-numeric: tabular-nums; }
table.rates caption { text-align: left; font-weight: 600; font-size: 14px; color: var(--muted); padding-bottom: 2px; }
table.rates th, table.rates td { border: 1px solid var(--line); padding: 4px 8px; text-align: left; }
table.rates th { font-weight: 500; }

/* answer boxes */
.part { border: 0; margin: 0; padding: 0; min-width: 0; }
.part .prompt, .part legend { display: block; font-weight: 600; font-size: 16px; line-height: 1.3; margin-bottom: 4px; color: var(--ink); }
.ain { display: flex; align-items: center; gap: 8px; }
.ain input { width: 10em; max-width: 100%; font-variant-numeric: tabular-nums; }
.unit, .cur { color: var(--muted); }
.opts { display: grid; gap: 6px; }
.opts.row { grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); }
.opts.four { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.opt { display: flex; align-items: center; gap: 8px; min-height: 44px; padding: 6px 10px; border: 1px solid var(--line); border-radius: 6px; cursor: pointer; }
.opt input { width: 20px; height: 20px; min-height: 0; margin: 0; accent-color: var(--accent); flex: none; }
.opt i { font-style: normal; font-weight: 700; color: var(--muted); }
.part.is-right input:not([type="radio"]) { border-color: var(--ok); background: var(--ok-soft); }
.part.is-wrong input:not([type="radio"]) { border-color: var(--bad); background: var(--bad-soft); }
.part.is-close input:not([type="radio"]) { border-color: var(--close); background: var(--close-soft); }
.fb { margin: 4px 0 0; font-size: 15px; line-height: 1.4; padding: 4px 8px; border-radius: 6px; }
.fb.right { color: var(--ok); background: var(--ok-soft); }
.fb.wrong { color: var(--bad); background: var(--bad-soft); }
.fb.close, .fb.unread { color: var(--close); background: var(--close-soft); }
.qfoot { display: flex; gap: 10px; align-items: center; }
details.work { margin-top: 4px; border-top: 1px dashed var(--line); padding-top: 4px; }
details.work summary { cursor: pointer; color: var(--info); min-height: 44px; display: flex; align-items: center; font-weight: 600; }
details.work .figview { padding: 0; margin: 6px 0 8px; }
.ans { margin: 8px 0 2px; }
.steps { margin: 0 0 4px; padding-left: 20px; color: var(--muted); font-size: 15.5px; }
.sheet-foot { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 14px; margin: 14px 0 6px; }
.ask { display: inline-flex; flex-wrap: wrap; align-items: center; gap: 6px 10px; background: var(--accent-soft); padding: 6px 10px; border-radius: 6px; }
.share { margin: 16px 0 6px; }
.print-row { display: flex; flex-wrap: wrap; gap: 8px 12px; align-items: center; }
.print-row label { display: inline-flex; align-items: center; gap: 8px; font-weight: 600; }
.print-row select { max-width: 100%; }
.share-out label { display: grid; gap: 4px; font-weight: 600; margin-top: 8px; }
.share-out input { width: 100%; }
.recent { margin-top: 12px; background: var(--paper); border: 1px solid var(--line); border-radius: var(--r); padding: 4px 12px; }
.recent summary { cursor: pointer; min-height: 44px; display: flex; align-items: center; font-weight: 600; }
.recent ul { list-style: none; margin: 0; padding: 0; }
.recent li { display: flex; justify-content: space-between; align-items: center; gap: 10px; padding: 6px 0; border-top: 1px solid var(--line); }
.recent small { display: block; color: var(--muted); font-size: 14px; }
.hint { color: var(--muted); font-size: 14px; }
.toast { position: fixed; left: 50%; bottom: 16px; transform: translateX(-50%) translateY(150%); background: var(--ink); color: var(--paper); padding: 10px 16px; border-radius: 6px; max-width: min(92vw, 520px); font-size: 15.5px; transition: transform 0.2s; z-index: 20; }
.toast.on { transform: translateX(-50%) translateY(0); }
@media (prefers-reduced-motion: reduce) { .toast { transition: none; } }

/* ---------- content ---------- */
.content { max-width: 75ch; padding: 26px 0 20px; }
.content h2 { font-size: 25px; margin: 26px 0 6px; }
.tscroll { overflow-x: auto; }
/* under 400 px the comparison stacks: one block per source, each rule labeled, so nothing is cut off at 320 px */
.rstack { display: none; }
@media (max-width: 399px) {
  .tscroll { display: none; }
  .rstack { display: grid; gap: 8px; }
  .rcard { background: var(--paper); border: 1px solid var(--line); border-radius: 6px; overflow: hidden; }
  .rname { margin: 0; background: var(--band); color: var(--band-ink); font-weight: 600; padding: 5px 10px; }
  .rcard dl { display: grid; grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr); margin: 0; font-size: 15px; }
  .rcard dt, .rcard dd { margin: 0; padding: 4px 10px; border-top: 1px solid var(--line); overflow-wrap: anywhere; }
  .rcard dt { font-weight: 600; }
  .rcard dl > :nth-child(-n+2) { border-top: 0; }
}
table.ltab { border-collapse: collapse; width: 100%; font-size: 15px; background: var(--paper); }
table.ltab th, table.ltab td { border: 1px solid var(--line); padding: 5px 7px; text-align: left; vertical-align: top; }
table.ltab thead th { background: var(--band); color: var(--band-ink); font-weight: 600; }
table.ltab tbody th { font-weight: 600; }
.faq details { border-top: 1px solid var(--line); }
.faq summary { cursor: pointer; font-weight: 600; padding: 10px 0; min-height: 44px; }
.faq p { margin: 0 0 12px; }
.sources { font-size: 14.5px; color: var(--muted); }
footer { border-top: 1px solid var(--line); padding: 16px 0 28px; font-size: 14.5px; color: var(--muted); }
.indep { margin: 0 0 10px; }
.sb-footer p { margin: 6px 0; }
.sb-more { line-height: 1.8; }
.print-root { display: none; }

@media (min-width: 900px) {
  .setgrid { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) auto auto; }
  .setgrid .span { grid-column: auto; }
  .rl { columns: 2; column-gap: 32px; }
  .rl li { break-inside: avoid; }
  .qparts { grid-template-columns: 1fr 1fr; gap: 12px 22px; }
  .qparts .qfoot, .qparts details.work { grid-column: 1 / -1; }
}
@media (max-width: 480px) {
  .setgrid { gap: 8px 10px; }
  .sg span { font-size: 14px; padding: 4px 2px; }
  .hero { padding-top: 14px; }
  .lede { font-size: 16px; }
  .q h3 { font-size: 17.5px; padding: 8px 10px; }
  .scen { margin: 8px 10px 4px; }
  .figview { padding: 0 10px; }
  .qparts { padding: 8px 10px 12px; }
  table.ltab { font-size: 13.5px; }
  table.ltab th, table.ltab td { padding: 4px 4px; }
}

/* ---------- print ---------- */
@media print {
  :root { --ink: #000; --muted: #333; --line: #999; --paper: #fff; --edge: #555; --dial: #000; --face: #fff; --accent: #000; }
  @page { margin: 12mm 12mm; }
  body { background: #fff; color: #000; font: 10.5pt/1.36 var(--sans); }
  main, footer, .toast, .skip { display: none !important; }
  .print-root { display: block; }
  svg { print-color-adjust: exact; -webkit-print-color-adjust: exact; }
  table.pt { width: 100%; border-collapse: collapse; }
  table.pt > tbody > tr > td, table.pt > thead > tr > td { padding: 0; }
  .prun { font: 8.5pt var(--sans); color: #444; text-align: right; padding-bottom: 5pt !important; }
  .ph { display: flex; justify-content: space-between; align-items: baseline; gap: 10pt; border-bottom: 2pt solid #000; margin-bottom: 4pt; }
  .ph h2 { font: 700 16pt var(--head); margin: 0; white-space: nowrap; }
  .ph p { margin: 0; font-size: 9pt; text-align: right; }
  .pmeta { display: flex; justify-content: space-between; gap: 12pt; margin: 4pt 0 6pt; }
  .prules { border: 0.8pt solid #000; padding: 3pt 6pt; margin: 0 0 6pt; font-size: 8.6pt; break-inside: avoid; }
  .prules p { margin: 0 0 2pt; }
  .prules .rl { columns: 2; column-gap: 8mm; font-size: 8.6pt; margin: 0; padding-left: 12pt; }
  .prules .rl li { margin: 0 0 2pt; break-inside: avoid; }
  .prules .rl .src { display: inline; font-size: 7.6pt; color: #444; }
  .prules .rl .src::before { content: "("; }
  .prules .rl .src::after { content: ")"; }
  .pq { list-style: none; margin: 0; padding: 0; }
  .pq > li { padding: 5pt 0 6pt; border-bottom: 0.75pt solid #999; break-inside: avoid; page-break-inside: avoid; }
  .pq h3 { font: 700 12pt var(--head); margin: 0 0 2pt; }
  .pscen { margin: 0 0 4pt; }
  .pfig .meters { gap: 3mm 6mm; }
  .pfig svg.meter { width: auto; max-width: 100%; max-height: 50mm; }
  .pfig .meters.two svg.meter { max-height: 44mm; }
  .pfig .mwrap.wide, .pkfigs .mwrap.wide { flex: 0 0 100%; }
  .pfig .mwrap.wide svg.meter { max-height: 56mm; }
  .frame { fill: #fff; stroke: #000; }
  .cap { fill: #000; font-size: 13px; }
  table.rates { font-size: 9.5pt; margin: 4pt 0 2pt; }
  table.rates caption { font-size: 8.8pt; color: #000; }
  table.rates th, table.rates td { border-color: #000; padding: 1.5pt 5pt; }
  .pparts { display: grid; grid-template-columns: 1fr 1fr; gap: 1pt 8mm; font-size: 9.8pt; margin-top: 3pt; }
  .pparts .pp { break-inside: avoid; }
  .pparts .pp.wide { grid-column: 1 / -1; }
  .pparts .pp p { margin: 0; }
  .pline { margin: 6pt 0 3pt !important; }
  .popts span { margin-right: 10pt; display: inline-block; }
  .pkey { break-before: page; page-break-before: always; }
  .pk { list-style: none; margin: 0; padding: 0; }
  .pk > li { padding: 5pt 0 7pt; border-bottom: 0.75pt solid #999; break-inside: avoid; page-break-inside: avoid; }
  .pk h3 { font: 700 11.5pt var(--head); margin: 0 0 3pt; }
  .pkfigs { display: flex; flex-wrap: wrap; gap: 2mm 6mm; }
  .pkfigs svg.meter { max-height: 42mm; width: auto; max-width: 100%; }
  /* meters with test dials are tall: give them more height so the dials are not drawn smaller than the others, and set
     a previous/present pair side by side (QA 2026-10-26) */
  .pkfigs .mwrap.wide svg.meter { max-height: 52mm; }
  .pkfigs:has(> .mwrap.wide ~ .mwrap.wide) > .mwrap.wide { flex: 1 1 0; min-width: 0; }
  .kbox rect { stroke: #000; }
  .kd { fill: #000; }
  table.pkt { width: 100%; border-collapse: collapse; font-size: 9pt; margin-top: 3pt; table-layout: fixed; }
  table.pkt td { border-top: 0.5pt solid #bbb; padding: 2pt 4pt; vertical-align: top; }
  table.pkt td.pkq { width: 34%; }
  table.pkt td.pka { width: 18%; font-weight: 700; }
}