/* Stormtoplan – the look of a surface weather chart: chart paper, graphite ink, red fronts, blue isobars. */
:root {
  --paper: #e9e6dd; --paper-2: #f3f1ea; --ink: #141a22; --muted: #5f6873; --rule: #c9c5b9; --hair: rgba(20, 26, 34, .16);
  --front: #c62f1c; --isobar: #2d5a8a; --code-bg: #dedbd0;
  --sans: system-ui, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --serif: Charter, "Bitstream Charter", "Iowan Old Style", Cambria, Georgia, serif;
  --mono: ui-monospace, "Cascadia Mono", Consolas, Menlo, monospace;
}
@media (prefers-color-scheme: dark) {
  :root { --paper: #0f151c; --paper-2: #151d27; --ink: #e6e3d9; --muted: #9aa3ad; --rule: #2b3540; --hair: rgba(230, 227, 217, .16);
    --front: #ff6b52; --isobar: #8db4e3; --code-bg: #182230; }
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 17px/1.6 var(--serif); overflow-x: clip; }
a { color: var(--isobar); text-underline-offset: 3px; text-decoration-thickness: 1px; }
h1, h2, h3 { font-family: var(--sans); font-weight: 800; line-height: 1.02; margin: 0; letter-spacing: -.025em; }
pre { margin: 12px 0 0; padding: 12px 14px; background: var(--code-bg); border-left: 3px solid var(--ink); overflow-x: auto; font: 13px/1.5 var(--mono); }
code { font-family: var(--mono); }
b { font-weight: 700; }

.top, .hero, .sec, .foot, .station { width: min(1120px, 100% - 48px); margin-inline: auto; }

/* masthead: a band of ink across the whole width */
.top { display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 16px 0; background: var(--ink); color: var(--paper); box-shadow: 0 0 0 100vmax var(--ink); clip-path: inset(0 -100vmax); }
.brand { display: flex; align-items: center; gap: 11px; color: inherit; text-decoration: none; }
.brand img { display: block; }
.wordmark { font: 800 20px/1 var(--sans); letter-spacing: -.03em; }
.wordmark i { font: italic 400 18px var(--serif); letter-spacing: 0; opacity: .72; margin: 0 1px; }
.top nav { display: flex; align-items: center; gap: 22px; font: 12px var(--mono); text-transform: uppercase; letter-spacing: .08em; }
.top nav a { color: inherit; opacity: .78; text-decoration: none; }
.top nav a:hover { opacity: 1; }
.top nav .fb { color: var(--front); opacity: 1; filter: brightness(1.35); }
.top nav .open { opacity: 1; color: var(--ink); background: var(--paper); padding: 8px 14px; }
.top nav .open:hover { background: var(--front); color: #fff; }
.station { display: flex; justify-content: space-between; gap: 16px; padding: 8px 0; border-bottom: 1px solid var(--rule); font: 11px var(--mono); text-transform: uppercase; letter-spacing: .12em; color: var(--muted); }
.station span + span { text-align: right; }

/* hero */
.hero { display: grid; grid-template-columns: 1fr 1.05fr; gap: 48px; align-items: center; padding: 64px 0 72px; }
.label { margin: 0 0 20px; font: 12px var(--mono); text-transform: uppercase; letter-spacing: .14em; color: var(--front); }
.hero h1 { font-size: clamp(46px, 7.2vw, 92px); }
.hero h1 em { font-style: normal; color: var(--front); }
.lead { margin: 24px 0 0; max-width: 32em; font-size: 20px; line-height: 1.5; color: var(--ink); }
.cta { margin: 32px 0 0; display: flex; flex-wrap: wrap; align-items: center; gap: 12px 26px; }
.btn { display: inline-block; padding: 14px 24px; background: var(--ink); color: var(--paper); text-decoration: none; font: 700 15px var(--sans); border: 1px solid var(--ink); letter-spacing: -.01em; }
.btn:hover { background: var(--front); border-color: var(--front); color: #fff; }
.btn.alt { background: transparent; color: var(--ink); }
.btn.alt:hover { background: var(--front); color: #fff; }
.textlink { font: 15px var(--sans); color: var(--ink); }
.textlink:hover { color: var(--front); }

/* the chart */
.hero-art { margin: 0; }
.hero-art svg { display: block; width: 100%; height: auto; background: var(--paper-2); border: 1px solid var(--ink); }
.hero-art figcaption { margin-top: 10px; font: 12px/1.5 var(--mono); color: var(--muted); }
.chart-grid { stroke: var(--hair); stroke-width: 1; fill: none; }
.iso { fill: none; stroke: var(--isobar); stroke-width: 1.5; stroke-linejoin: round; }
.iso.far { stroke-width: 1.1; opacity: .55; }
.iso-label { font: 10px var(--mono); fill: var(--isobar); }
.low { font: italic 700 44px var(--serif); fill: var(--front); }
.low-val { font: 11px var(--mono); fill: var(--front); }
.front { fill: none; stroke: var(--front); stroke-width: 2.5; stroke-linecap: round; }
.front-sym { fill: var(--front); }
.plan-box { fill: var(--paper-2); stroke: var(--ink); stroke-width: 2; }
.plan-edge { stroke: var(--ink); stroke-width: 2; fill: none; }
.plan-head { fill: var(--ink); }
.plan-txt { font: 600 15px var(--sans); fill: var(--ink); letter-spacing: -.01em; }
.chart-note { font: 10px var(--mono); fill: var(--muted); letter-spacing: .08em; }

/* sections */
.sec { padding: 64px 0; border-top: 1px solid var(--rule); }
.sec-head { display: flex; align-items: baseline; gap: 18px; }
.no { font: 12px var(--mono); color: var(--front); letter-spacing: .1em; }
.no::before { content: "§ "; }
.sec h2 { font-size: clamp(30px, 4vw, 46px); }
.sec-intro { max-width: 38em; margin: 16px 0 0 calc(4ch + 18px); font-size: 19px; color: var(--muted); }
.sec > p { max-width: 44em; }

.rows { margin: 40px 0 0; }
.rows > div { display: grid; grid-template-columns: 260px 1fr; gap: 12px 40px; padding: 24px 0; border-top: 1px solid var(--rule); }
.rows dt { font: 700 22px/1.15 var(--sans); letter-spacing: -.02em; }
.rows dd { margin: 0; max-width: 44em; }

.formats { display: grid; grid-template-columns: repeat(5, 1fr); margin-top: 40px; border-top: 3px solid var(--ink); }
.formats article { padding: 22px 18px 10px 0; min-width: 0; }
.formats article + article { padding-left: 18px; border-left: 1px solid var(--rule); }
.formats h3 { font-size: 21px; }
.formats p { margin: 8px 0 0; color: var(--muted); font-size: 15px; }
.note { margin: 28px 0 0; font: 13px/1.6 var(--mono); color: var(--muted); max-width: 70em; }

.spec { list-style: none; margin: 36px 0 0; padding: 0; border-top: 3px solid var(--ink); }
.spec li { display: grid; grid-template-columns: 180px 1fr; gap: 24px; padding: 14px 0; border-bottom: 1px solid var(--rule); }
.spec li span:first-child { font: 12px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); padding-top: 5px; }
.sec .cta { margin-top: 40px; }
.feedback-box { margin-top: 48px; padding: 22px 24px 24px; border-top: 3px solid var(--front); border-bottom: 1px solid var(--rule); max-width: 40em; }
.feedback-box h3 { font-size: 24px; }
.feedback-box p { margin: 8px 0 0; color: var(--muted); }
.feedback-box .btn { margin-top: 8px; }

details { border-top: 1px solid var(--rule); padding: 18px 0; max-width: 46em; }
details:last-of-type { border-bottom: 1px solid var(--rule); }
summary { cursor: pointer; font: 700 19px var(--sans); letter-spacing: -.015em; list-style: none; display: flex; justify-content: space-between; gap: 16px; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; font: 400 22px/1 var(--mono); color: var(--front); }
details[open] summary::after { content: "−"; }
details p { margin: 12px 0 0; color: var(--muted); }
.sec-head + details { margin-top: 36px; }

.foot { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; padding: 28px 0 56px; border-top: 3px solid var(--ink); font: 12px var(--mono); text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.foot nav { display: flex; flex-wrap: wrap; gap: 22px; }
.foot a { color: var(--muted); text-decoration: none; }
.foot a:hover { color: var(--ink); }

:focus-visible { outline: 3px solid var(--front); outline-offset: 3px; }

/* conversion demo and the table */
.demo { display: grid; grid-template-columns: 1fr 1fr; gap: 0 28px; margin-top: 36px; }
.demo h3 { font: 12px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); font-weight: 400; }
.demo .loss { grid-column: 1 / -1; margin-top: 26px; border-left: 3px solid var(--front); padding-left: 18px; }
.demo .loss h3 { color: var(--front); }
.demo .loss ul { list-style: none; margin: 8px 0 0; padding: 0; }
.demo .loss li { display: grid; grid-template-columns: 70px minmax(0, 1fr); gap: 2px 14px; padding: 8px 0; border-top: 1px solid var(--rule); }
.demo .loss b { font: 12px var(--mono); font-weight: 400; color: var(--muted); grid-row: span 2; padding-top: 2px; }
.demo .loss code { font-size: 13px; overflow-wrap: anywhere; }
.demo .loss span { color: var(--muted); font-size: 15px; }

.matrix { margin-top: 36px; overflow-x: auto; }
.matrix table { width: 100%; border-collapse: collapse; font-size: 15px; }
.matrix caption { text-align: left; padding-bottom: 10px; font: 12px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); }
.matrix th, .matrix td { padding: 11px 16px 11px 0; text-align: left; border-top: 1px solid var(--rule); white-space: nowrap; }
.matrix thead th { font: 11px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); font-weight: 400; border-top: 0; }
.matrix tbody tr:first-child th, .matrix tbody tr:first-child td { border-top: 3px solid var(--ink); }
.matrix tbody th { font: 700 16px var(--sans); letter-spacing: -.01em; }
.matrix .no-conv { color: var(--muted); }
.matrix kbd { font: 12px var(--mono); padding: 1px 6px; border: 1px solid var(--rule); background: var(--paper-2); }

/* guide and documentation pages */
.hero.single { grid-template-columns: 1fr; padding: 56px 0 48px; }
.hero.single h1 { font-size: clamp(36px, 5.6vw, 64px); max-width: 14em; }
.hero.single .lead { max-width: 40em; }
.cta .note { margin: 0; }
.sec pre + pre { margin-top: 8px; }
.sec .steps { margin: 24px 0 0; padding: 0; list-style: none; counter-reset: step; max-width: 44em; }
.sec .steps li { position: relative; padding: 10px 0 10px 56px; border-top: 1px solid var(--rule); counter-increment: step; }
.sec .steps li::before { content: counter(step, decimal-leading-zero); position: absolute; left: 0; top: 14px; font: 12px var(--mono); color: var(--front); letter-spacing: .08em; }
.related { margin: 20px 0 0; padding: 0; list-style: none; max-width: 36em; border-top: 3px solid var(--ink); }
.related li { padding: 10px 0; border-bottom: 1px solid var(--rule); }
.related a { color: var(--ink); font: 700 17px var(--sans); text-decoration: none; letter-spacing: -.01em; }
.related a:hover { color: var(--front); }
kbd { font: 12px var(--mono); padding: 1px 6px; border: 1px solid var(--rule); background: var(--paper-2); }

@media (max-width: 900px) {
  .hero > *, .formats > *, .rows > div > * { min-width: 0; }
  .hero { grid-template-columns: 1fr; gap: 36px; padding: 44px 0 56px; }
  .top nav a:not(.open) { display: none; }
  .station span + span { display: none; }
  .rows > div { grid-template-columns: 1fr; }
  .formats { grid-template-columns: 1fr; }
  .formats article, .formats article + article { padding: 20px 0; border-left: 0; border-top: 1px solid var(--rule); }
  .formats article:first-child { border-top: 0; }
  .spec li { grid-template-columns: 1fr; gap: 2px; }
  .sec-intro { margin-left: 0; }
  .demo { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

/* Easter egg: piggy.js toggles html.piggy (remembered, and also applied on the other pages) */
:root.piggy { --paper: #fdeef3; --paper-2: #fff6f9; --ink: #4a1a2c; --muted: #9a5b72; --rule: #f3c1d3; --hair: rgba(214, 51, 108, .14);
  --isobar: #d6336c; --front: #f06595; --code-bg: #fbdce7; }
@media (prefers-color-scheme: dark) {
  :root.piggy { --paper: #2b0f1c; --paper-2: #35142a; --ink: #ffe3ee; --muted: #e6a1bb; --rule: #5e2a40; --hair: rgba(255, 168, 197, .14);
    --isobar: #ff8fb8; --front: #ffa8c5; --code-bg: #220a15; }
}
:root.piggy body { transition: background-color .4s, color .4s; }
.piggy-btn { display: block; margin: 18px 0 0 auto; padding: 4px; background: none; border: 0; cursor: pointer; opacity: .18; transition: opacity .2s; }
.piggy-btn:hover, .piggy-btn:focus-visible, .piggy .piggy-btn { opacity: 1; }
.piggy-btn svg { display: block; fill: var(--muted); }
.piggy .piggy-btn svg, .piggy-btn:hover svg { fill: #f4a6c0; }
.piggy-btn .snout { fill: var(--paper); opacity: .5; }
.piggy-btn .eye { fill: var(--ink); }
.piggy-btn.oink { animation: oink .5s ease; }
@keyframes oink { 0%, 100% { transform: rotate(0); } 25% { transform: rotate(-14deg) scale(1.2); } 75% { transform: rotate(10deg) scale(1.2); } }
@media (prefers-reduced-motion: reduce) { .piggy-btn.oink { animation: none; } :root.piggy body { transition: none; } }