/* Radar Plotting Practice: a maneuvering board printed in green on white (as NGA charts 5090 and 5091 are), navy
   chart ink, a grease-pencil red for plots and the relative movement line, and a radar-phosphor night mode. Numbers in
   a monospace so bearings line up. On paper: black and green line work at true scale, 1 nm = 6 mm. */
:root {
  --bg: #eef3ef;
  --paper: #ffffff;
  --ink: #0f2233;
  --muted: #4a5a63;
  --line: #cbd8cf;
  --edge: #7f948a;
  --accent: #0f4c6e;
  --accent-ink: #ffffff;
  --accent-soft: #dcebf2;
  --grid: #2a7a4f;
  --grid-soft: #9cc7ae;
  --pencil: #c0262d;
  --vec: #1d1d1d;
  --vtrue: #157a3b;
  --vnew: #1559a8;
  --ok: #17663a;
  --ok-soft: #dcefe2;
  --close: #7a5300;
  --close-soft: #f6ebd2;
  --bad: #a2261f;
  --bad-soft: #f8e1de;
  --focus: #c25a00;
  --head: "Gill Sans", "Gill Sans MT", Seravek, "Trebuchet MS", Calibri, "Segoe 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: 4px;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #08130f;
    --paper: #0d1c17;
    --ink: #dcefe5;
    --muted: #9db5a9;
    --line: #1f3a30;
    --edge: #4d6e60;
    --accent: #ffb547;
    --accent-ink: #1f1300;
    --accent-soft: #33240c;
    --grid: #52d68f;
    --grid-soft: #2b6b4a;
    --pencil: #ff6b6b;
    --vec: #e8f3ec;
    --vtrue: #7ef0a8;
    --vnew: #7cb8ff;
    --ok: #8adca6;
    --ok-soft: #14301f;
    --close: #f0c56b;
    --close-soft: #352a12;
    --bad: #ff9c8f;
    --bad-soft: #3a1c18;
    --focus: #ffd27a;
  }
}
* { 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); }
a { color: var(--accent); }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }
.skip { position: absolute; left: -999px; top: 0; background: var(--paper); padding: 8px 12px; z-index: 10; }
.skip:focus { left: 8px; }
[hidden] { display: none !important; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.wrap { max-width: 1180px; margin: 0 auto; padding: 0 16px; }
.hero { padding: 22px 0 10px; border-bottom: 3px solid var(--grid); margin-bottom: 16px; }
h1 { font: 600 clamp(1.75rem, 5vw, 2.55rem)/1.08 var(--head); margin: 0 0 6px; letter-spacing: 0.01em; }
.lede { margin: 0; max-width: 62ch; color: var(--muted); }
h2 { font: 600 1.35rem/1.2 var(--head); margin: 0 0 10px; }
h3 { font: 600 1.15rem/1.25 var(--head); margin: 0; }

/* setup */
.tool { display: grid; gap: 16px; }
@media (min-width: 900px) { .tool { grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr); } .work-area { grid-column: 1 / -1; } }
.setup { display: grid; gap: 12px; align-content: start; }
.setgrid { display: grid; gap: 12px; grid-template-columns: minmax(0, 1fr); }
@media (min-width: 560px) { .setgrid { grid-template-columns: minmax(0, 3fr) minmax(0, 2fr); } }
fieldset { border: 0; margin: 0; padding: 0; min-width: 0; }
legend { font-weight: 600; padding: 0; margin-bottom: 4px; }
.seg { display: grid; border: 1px solid var(--edge); border-radius: var(--r); overflow: hidden; background: var(--paper); }
.seg3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.seg2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.sg { position: relative; }
.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; min-height: 44px; padding: 4px 6px; text-align: center; font: 600 0.95rem/1.15 var(--head); }
.sg input:checked + span { background: var(--accent); color: var(--accent-ink); }
.sg input:focus-visible + span { outline: 3px solid var(--focus); outline-offset: -3px; }
.tdet { border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); padding: 6px 0; }
.tdet summary { cursor: pointer; font-weight: 600; min-height: 36px; display: flex; align-items: center; gap: 6px; }
.tsum { font-weight: 400; color: var(--muted); font-size: 0.92rem; }
.toggles { display: grid; gap: 6px; grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); padding: 6px 0; }
.tg { display: flex; gap: 8px; align-items: flex-start; padding: 6px 8px; border: 1px solid var(--line); border-radius: var(--r); background: var(--paper); cursor: pointer; }
.tg input { width: 20px; height: 20px; margin: 2px 0 0; accent-color: var(--accent); flex: none; }
.tg b { display: block; font: 600 0.95rem/1.2 var(--head); }
.tg small { color: var(--muted); font-size: 0.9rem; }
.setrow { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.inline { display: flex; gap: 8px; align-items: center; font-weight: 600; }
select, input { font: inherit; font-size: 16px; color: var(--ink); background: var(--paper); border: 1px solid var(--edge); border-radius: var(--r); min-height: 44px; padding: 6px 8px; }
.btn { font: 600 1rem/1 var(--sans); min-height: 44px; padding: 10px 16px; border-radius: var(--r); border: 1px solid var(--accent); background: var(--paper); color: var(--accent); cursor: pointer; }
.btn.primary { background: var(--accent); color: var(--accent-ink); }
.btn.small { min-height: 40px; padding: 8px 12px; font-size: 0.95rem; }
.btn:hover { filter: brightness(1.08); }
.link { background: none; border: 0; color: var(--accent); text-decoration: underline; font: inherit; cursor: pointer; padding: 8px 4px; min-height: 44px; }

.refcard { background: var(--paper); border-left: 4px solid var(--grid); padding: 12px 14px; align-self: start; }
.refcard h2 { font-size: 1.1rem; }
.refcard dl { margin: 0; display: grid; gap: 4px 10px; grid-template-columns: minmax(0, 7.5em) minmax(0, 1fr); font-size: 0.93rem; }
.refcard dt { font-weight: 600; }
.refcard dd { margin: 0; color: var(--muted); }
@media (max-width: 899px) { .refcard { order: 3; } }

.note { margin: 0 0 10px; padding: 10px 12px; border-left: 4px solid var(--bad); background: var(--bad-soft); }
.note.info { border-color: var(--accent); background: var(--accent-soft); }
section.sheet { background: var(--paper); border-top: 4px solid var(--accent); padding: 12px 14px 14px; }
section.sheet:focus { outline: none; }
.sheet-head { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: baseline; gap: 4px 16px; }
.code { font-family: var(--mono); letter-spacing: 0.08em; color: var(--accent); }
.score { margin: 0; color: var(--muted); font-size: 0.95rem; }
.practice { margin: 2px 0 8px; color: var(--muted); font-size: 0.93rem; }
.qs { list-style: none; margin: 0; padding: 0; }
.q { padding: 14px 0 16px; border-top: 1px solid var(--line); }
.q:first-child { border-top: 0; }
.qhead { display: flex; align-items: baseline; gap: 10px; }
.qn { color: var(--grid); margin-right: 6px; font-family: var(--mono); }
.scen { margin: 4px 0 10px; max-width: 75ch; }
.qbody { display: grid; gap: 14px; }
@media (min-width: 1000px) { .qbody { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); align-items: start; } }
.obswrap { overflow-x: auto; }
table.obs { border-collapse: collapse; font-family: var(--mono); font-size: 0.95rem; margin: 0 0 8px; }
table.obs th, table.obs td { border: 1px solid var(--line); padding: 4px 9px; text-align: right; white-space: nowrap; }
table.obs thead th { font: 600 0.85rem/1.2 var(--sans); text-align: center; background: var(--bg); }
/* three targets on a phone: tighter cells, and the unit headers may wrap ("Range, / nm") */
@media (max-width: 480px) {
  table.obs.multi { font-size: 0.86rem; }
  table.obs.multi th, table.obs.multi td { padding: 3px 4px; }
  table.obs.multi thead th { font-size: 0.74rem; white-space: normal; }
}
@media (max-width: 359px) {
  .q .qparts, .q .qdata { margin-left: -6px; margin-right: -6px; }
  table.obs.multi { font-size: 0.78rem; letter-spacing: -0.02em; }
  table.obs.multi th, table.obs.multi td { padding: 2px 2px; }
  table.obs.multi thead th { font-size: 0.68rem; }
}
table.obs tbody th { font-weight: 600; }
.figtools { display: flex; flex-wrap: wrap; gap: 8px 14px; align-items: center; margin: 4px 0 6px; }
.chk { display: flex; gap: 8px; align-items: center; min-height: 44px; cursor: pointer; }
.chk input { width: 20px; height: 20px; min-height: 0; accent-color: var(--accent); }
.qdata { min-width: 0; }
.figview { overflow-x: auto; max-width: 100%; }
.figview svg { display: block; width: 100%; max-width: 560px; height: auto; }
.zoomed .figview svg { width: 900px; max-width: none; }

/* the sheets */
svg.sheet { font-family: var(--sans); }
svg.sheet .face { fill: var(--paper); stroke: var(--grid); stroke-width: 0.45; }
svg.sheet .ring { fill: none; stroke: var(--grid); stroke-width: 0.18; }
svg.sheet .ring.outer { stroke-width: 0.45; }
svg.sheet .ring.mid { stroke-width: 0.3; }
svg.sheet .rad { stroke: var(--grid-soft); stroke-width: 0.15; }
svg.sheet .rad.dotted { stroke: var(--grid); stroke-dasharray: 0.3 0.9; stroke-width: 0.2; }
svg.sheet .tk { stroke: var(--grid); stroke-width: 0.15; fill: none; }
svg.sheet .tk5 { stroke-width: 0.22; }
svg.sheet .tk10 { stroke-width: 0.32; }
svg.sheet .bl { font-size: 3.1px; text-anchor: middle; fill: var(--ink); }
svg.sheet .rb { font-size: 1.9px; text-anchor: middle; fill: var(--muted); }
svg.sheet .rl { font-size: 2.4px; fill: var(--grid); }
svg.sheet .hdg { stroke: var(--ink); stroke-width: 0.3; stroke-dasharray: 2 1.2; }
svg.sheet .own { fill: var(--ink); }
svg.sheet .cap { font-size: 2.7px; fill: var(--muted); }
svg.sheet .bar, svg.sheet .bt { stroke: var(--ink); stroke-width: 0.25; }
svg.sheet .bn { font-size: 2.4px; text-anchor: middle; fill: var(--ink); }
svg.sheet .bc { font-size: 2.4px; fill: var(--ink); }
svg.sheet .plot { fill: var(--pencil); }
svg.sheet .pl, svg.sheet .kl { font-size: 2.7px; fill: var(--ink); font-weight: 600; }
svg.sheet .rml { stroke: var(--pencil); stroke-width: 0.4; fill: none; }
svg.sheet .rml.ah { fill: none; }
svg.sheet .nrml { stroke: var(--vnew); stroke-width: 0.4; }
svg.sheet .perp { stroke: var(--vec); stroke-width: 0.25; stroke-dasharray: 1 0.7; }
svg.sheet .vown, svg.sheet .vtrue, svg.sheet .vrel, svg.sheet .vnew, svg.sheet .par { stroke: var(--vec); stroke-width: 0.38; fill: none; }
svg.sheet .vtrue { stroke: var(--vtrue); }
svg.sheet .vrel { stroke: var(--pencil); }
svg.sheet .vnew { stroke: var(--vnew); }
svg.sheet .par { stroke-dasharray: 1 0.8; stroke-width: 0.28; }
svg.sheet .dz { fill: none; stroke: var(--vnew); stroke-width: 0.28; stroke-dasharray: 1.6 1; }
svg.sheet .kp { fill: var(--vec); }
svg.sheet .kp.cpa, svg.sheet .kp.ncpa { fill: var(--pencil); }

/* answers */
.qparts { min-width: 0; }
.grp { margin: 0 0 10px; }
.grp h4 { font: 600 1rem/1.2 var(--head); margin: 0 0 6px; color: var(--accent); }
.grp.avoid { border-top: 1px dashed var(--edge); padding-top: 8px; }
.pgrid { display: grid; gap: 10px 12px; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); align-items: end; }
.part { min-width: 0; }
.part.wide { grid-column: 1 / -1; }
.prompt { display: block; font-size: 0.9rem; line-height: 1.25; margin-bottom: 3px; }
.ain { display: flex; align-items: center; gap: 6px; }
.ain input { width: 100%; max-width: 9.5em; font-family: var(--mono); }
.unit { color: var(--muted); font-size: 0.9rem; }
fieldset.part legend { font-weight: 400; font-size: 0.9rem; }
.opts { display: flex; flex-wrap: wrap; gap: 6px; }
.opt { display: flex; gap: 6px; align-items: center; min-height: 44px; padding: 4px 10px; border: 1px solid var(--line); border-radius: var(--r); background: var(--paper); cursor: pointer; }
.opt input { width: 20px; height: 20px; min-height: 0; accent-color: var(--accent); }
.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: 3px 0 0; font-size: 0.88rem; line-height: 1.3; }
.fb.right { color: var(--ok); }
.fb.wrong, .fb.unread { color: var(--bad); }
.fb.close { color: var(--close); }
.qfoot { display: flex; flex-wrap: wrap; gap: 6px 14px; align-items: center; margin: 6px 0 4px; }
.tolnote { color: var(--muted); font-size: 0.88rem; }
.work { margin-top: 8px; border-top: 1px solid var(--line); padding-top: 6px; }
.work summary { cursor: pointer; font-weight: 600; color: var(--accent); min-height: 40px; display: flex; align-items: center; }
.keyfig svg { display: block; width: 100%; max-width: 520px; height: auto; margin: 4px 0 8px; }
.ans { margin: 8px 0 2px; }
.steps { margin: 0; padding-left: 20px; color: var(--muted); font-size: 0.93rem; }
.trail { color: var(--muted); font-size: 0.93rem; }
.sheet-foot .saved { flex-basis: 100%; margin: 0; }
.sheet-foot { display: flex; flex-wrap: wrap; gap: 8px 14px; align-items: center; border-top: 1px solid var(--line); padding-top: 10px; }
.ask { display: inline-flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.share { margin-top: 14px; }
.print-row { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.print-row label { display: flex; gap: 8px; align-items: center; font-weight: 600; }
.share-out label { display: grid; gap: 4px; font-weight: 600; }
.share-out input { width: 100%; font-family: var(--mono); font-size: 14px; }
.recent { margin-top: 12px; }
.recent summary { cursor: pointer; font-weight: 600; min-height: 44px; display: flex; align-items: center; }
.recent ul { list-style: none; margin: 0; padding: 0; }
.recent li { display: flex; justify-content: space-between; gap: 10px; align-items: center; padding: 6px 0; border-bottom: 1px solid var(--line); }
.recent small { display: block; color: var(--muted); }
.hint { color: var(--muted); font-size: 0.9rem; }
.toast { position: fixed; left: 50%; bottom: 16px; transform: translate(-50%, 140%); max-width: min(92vw, 520px); background: var(--ink); color: var(--paper); padding: 10px 14px; border-radius: var(--r); transition: transform 0.2s; z-index: 20; }
.toast.on { transform: translate(-50%, 0); }
@media (prefers-reduced-motion: reduce) { .toast { transition: none; } }

/* content */
.content { max-width: 75ch; padding: 28px 0 12px; }
.content p { margin: 0 0 16px; }
.ltab { width: 100%; border-collapse: collapse; font-size: 0.93rem; margin-bottom: 20px; }
.ltab th, .ltab td { text-align: left; vertical-align: top; padding: 6px 8px; border-bottom: 1px solid var(--line); }
.ltab thead th { border-bottom: 2px solid var(--grid); }
.faq details { border-bottom: 1px solid var(--line); padding: 4px 0; }
.faq summary { cursor: pointer; font-weight: 600; min-height: 44px; display: flex; align-items: center; }
.faq p { margin: 4px 0 10px; }
.sources { font-size: 0.9rem; color: var(--muted); }
footer { border-top: 3px solid var(--grid); margin-top: 24px; padding: 16px 0 28px; font-size: 0.92rem; color: var(--muted); }
.indep { margin: 0 0 10px; }
.sb-footer p { margin: 0 0 8px; }
.sb-more { line-height: 1.7; }
.print-root { display: none; }
@media (max-width: 480px) {
  .pgrid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .refcard dl { grid-template-columns: minmax(0, 1fr); }
  .refcard dd { margin-bottom: 4px; }
}

/* ---------- print: one page per plotting sheet, then the key; the sheet at 1 nm = 6 mm ---------- */
@page { margin: 9mm; }
@media print {
  :root { --ink: #000; --muted: #333; --paper: #fff; --grid: #1f6b43; --grid-soft: #8db99f; --pencil: #b3121b; --vec: #000; --vtrue: #12652f; --vnew: #0b4a96; --line: #999; }
  body { background: #fff; color: #000; font: 9.5pt/1.32 var(--sans); }
  main, footer, .toast, .skip { display: none !important; }
  .print-root { display: block; }
  svg { print-color-adjust: exact; -webkit-print-color-adjust: exact; }
  .ppage { break-before: page; page-break-before: always; }
  .ppage:first-child { break-before: auto; page-break-before: auto; }
  .ph { display: flex; justify-content: space-between; align-items: baseline; border-bottom: 1.5pt solid #000; margin-bottom: 2mm; }
  .ph h2 { font: 600 13pt var(--head); margin: 0; }
  .ph p { margin: 0; font-size: 9pt; }
  .pmeta { display: flex; justify-content: space-between; gap: 8mm; margin: 0 0 1.5mm; font-size: 8.5pt; }
  .ptop { display: flex; gap: 6mm; align-items: flex-start; }
  .pscen { flex: 1 1 auto; }
  .pscen h3 { font: 600 10.5pt var(--head); margin: 0 0 1mm; }
  .pscen p { margin: 0; font-size: 8.6pt; line-height: 1.28; }
  .ptop .obswrap { flex: none; overflow: visible; }
  table.obs { font-size: 8.5pt; margin: 0; }
  table.obs th, table.obs td { padding: 0.6mm 2mm; border-color: #777; }
  table.obs thead th { background: #fff; font-size: 8pt; }
  .psvg { margin: 1mm 0 0; break-inside: avoid; }
  .psvg svg.sheet { display: block; width: 168mm; height: auto; margin: 0 auto; }
  .psvg svg.sheet.mob { width: 152mm; }
  .psvg svg.sheet .face { fill: #fff; }
  table.pgrid-t { width: 100%; border-collapse: collapse; table-layout: fixed; font-size: 8.5pt; margin: 1.5mm 0 1mm; }
  table.pgrid-t th, table.pgrid-t td { border: 0.6pt solid #777; height: 5.3mm; padding: 0 1.2mm; text-align: center; }
  table.pgrid-t thead th { height: auto; padding: 0.6mm 1mm; font-weight: 600; line-height: 1.1; }
  table.pgrid-t tbody th { width: 13mm; }
  table.pgrid-t .na { color: #777; font-size: 7.5pt; }
  .pparts { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0 4mm; font-size: 8.2pt; }
  .pp.pch { grid-column: 1 / -1; }
  .pp { margin: 0; display: flex; align-items: flex-end; gap: 2mm; min-height: 6mm; break-inside: avoid; }
  .pp .pline { flex: 1 1 10mm; min-width: 10mm; border-bottom: 0.6pt solid #000; height: 4mm; }
  .pp .pl { white-space: nowrap; }
  .pp .popts { white-space: pre-wrap; }
  .pkbody { display: block; }
  .pkfig svg.sheet { display: block; width: 104mm; height: auto; margin: 0 auto 2mm; }
  .pkt { width: 100%; border-collapse: collapse; font-size: 8pt; line-height: 1.25; }
  .pkt .prun { border: 0; text-align: right; font-size: 7.5pt; color: #555; padding: 0 0 1mm; }
  .pkt td { border-bottom: 0.5pt solid #bbb; padding: 0.8mm 2mm 0.8mm 0; vertical-align: top; }
  .pkt tr { break-inside: avoid; page-break-inside: avoid; }
  .pkt .pkq { width: 28%; }
  .pkt .pka { width: 14%; font-weight: 700; white-space: nowrap; }
  .pkt .pkw { color: #222; }
  .pkt .pkt-tol { display: block; font-weight: 400; font-size: 7pt; color: #444; }
  .ptol { font-size: 8.5pt; margin: 0 0 1mm; }
}