/* The site's style. Every colour is one an Atari ST can show (each channel one of its eight
   levels: 00 24 49 6D 92 B6 DB FF). The page is the deep blue of space behind the game; the
   numeral in the hero carries the copper bars of the ST's raster tricks; the bands of the frame's
   budget are the colours the app paints the ST's border with while it times itself. Headings are
   set in Press Start 2P, the 8 x 8 font the cartridge draws its own screens with; the reading
   text in Source Serif 4. */

@font-face {
  font-family: "Press Start 2P";
  src: url("fonts/press-start-2p.woff2") format("woff2");
  font-display: swap;
}
@font-face {
  font-family: "Source Serif 4";
  src: url("fonts/source-serif-4.woff2") format("woff2");
  font-weight: 200 900;
  font-display: swap;
}
@font-face {
  font-family: "Source Serif 4";
  src: url("fonts/source-serif-4-italic.woff2") format("woff2");
  font-weight: 200 900;
  font-style: italic;
  font-display: swap;
}

:root {
  --space: #000024;
  --deep: #000049;
  --rule: #24246d;
  --text: #dbdbdb;
  --muted: #9292b6;
  --head: #ffffb6;
  --link: #6ddbff;
  --rp: #6ddbff;
  --cart: #ffb600;
  --st: #ffffff;
  --copy: #ffffff;
  --sound: #6d6dff;
  --spare: #49ff49;
  --pixel: "Press Start 2P", ui-monospace, monospace;
  --serif: "Source Serif 4", Charter, "Iowan Old Style", Georgia, serif;
  --measure: 40rem;
  --gutter: clamp(16px, 4vw, 48px);
  /* the copper bars: the ST's palette, one colour a band */
  --copper: repeating-linear-gradient(180deg,
    #ffff6d 0 0.125em, #ffdb24 0.125em 0.25em, #ffb600 0.25em 0.375em,
    #ff6d00 0.375em 0.5em, #db2449 0.5em 0.625em, #b60092 0.625em 0.75em,
    #6d00b6 0.75em 0.875em, #b60092 0.875em 1em, #db2449 1em 1.125em,
    #ff6d00 1.125em 1.25em, #ffb600 1.25em 1.375em, #ffdb24 1.375em 1.5em);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: 4.5rem; }
@media (prefers-reduced-motion: no-preference) { html { scroll-behavior: smooth; } }
body {
  margin: 0;
  background: var(--space);
  color: var(--text);
  font: 400 1.125rem/1.7 var(--serif);
  font-variant-numeric: oldstyle-nums proportional-nums;
  overflow-x: hidden;
}

a { color: var(--link); text-decoration-thickness: 1px; text-underline-offset: 0.18em; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--head); outline-offset: 3px; }
code { font: 0.92em ui-monospace, "SF Mono", Menlo, Consolas, monospace; color: var(--head); }
b, strong { font-weight: 650; }
img { max-width: 100%; height: auto; }

.skip { position: absolute; left: -999px; top: 0; z-index: 10; padding: 0.5rem 1rem; background: var(--head); color: var(--space); }
.skip:focus { left: 0; }

/* ---- the bar at the top ---- */

.top {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem 1.5rem;
  padding: 0.85rem var(--gutter);
  background: var(--space);
  border-bottom: 1px solid var(--rule);
}
.top .name { font: 0.7rem/1.4 var(--pixel); color: var(--head); text-decoration: none; }
.top .name span { color: var(--cart); }
.top nav { display: flex; gap: 1.25rem; font-size: 1rem; }
.top nav a { color: var(--text); text-decoration: none; }
.top nav a:hover { color: var(--link); text-decoration: underline; }

/* ---- the hero ---- */

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 2.5rem;
  max-width: 76rem;
  margin: 0 auto;
  padding: clamp(2.5rem, 7vw, 5.5rem) var(--gutter) 3rem;
}
@media (min-width: 64rem) {
  .hero { grid-template-columns: minmax(0, 30rem) minmax(0, 1fr); align-items: center; column-gap: 4rem; }
  .hero .tape { grid-column: 1 / -1; }
}
.hero h1 {
  margin: 0 0 1.75rem;
  font: 400 clamp(1rem, 2.4vw, 1.35rem)/1.7 var(--pixel);
  color: var(--head);
}
.hero h1 .big {
  display: block;
  margin-bottom: 0.35em;
  font-size: clamp(6.5rem, 22vw, 11rem);
  line-height: 1;
  letter-spacing: -0.04em;
  color: #ffb600;
  background: var(--copper);
  background-size: 100% 1.5em;
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.lede { margin: 0 0 1rem; max-width: 34rem; font-size: 1.2rem; }

.screen { margin: 0; }
.screen img {
  display: block;
  width: 100%;
  image-rendering: pixelated;
  background: #000;
  border: 1px solid var(--rule);
}
.screen figcaption, figure > figcaption {
  margin-top: 0.6rem;
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--muted);
}

/* the 20 ms of a frame, as the ST's border shows it */
.tape { margin: 0; }
.tape-bar, .bar { display: flex; width: 100%; }
.tape-bar { height: 0.75rem; }
.tape-bar span, .bar span { display: block; min-width: 2px; }
.t-copy { background: var(--copy); }
.t-sound { background: var(--sound); }
.t-spare { background: var(--spare); }
.k-copy, .k-sound, .k-spare { font-weight: 600; }
.k-copy { color: var(--copy); }
.k-sound { color: #9292ff; }
.k-spare { color: var(--spare); }
.tape figcaption { max-width: 48rem; }

/* ---- the article ---- */

.layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  max-width: 76rem;
  margin: 0 auto;
  padding: 0 var(--gutter) 4rem;
  border-top: 1px solid var(--rule);
}
@media (min-width: 64rem) {
  .layout { grid-template-columns: 14rem minmax(0, var(--measure)); column-gap: 4rem; }
}

.contents { padding-top: 3rem; font-size: 0.98rem; }
.contents-title { margin: 0 0 0.75rem; font: 0.6rem/1.6 var(--pixel); color: var(--muted); }
.contents ol { margin: 0; padding: 0; list-style: none; }
.contents li { margin: 0 0 0.35rem; }
.contents a { color: var(--text); text-decoration: none; }
.contents a:hover { color: var(--link); text-decoration: underline; }
@media (min-width: 64rem) {
  .contents { align-self: start; position: sticky; top: 4.5rem; }
}
@media (max-width: 63.99rem) {
  .contents { padding-top: 2rem; }
  .contents ol { columns: 2 12rem; column-gap: 2rem; }
}

main { min-width: 0; }
main section { padding-top: 3.5rem; }
main h2 {
  margin: 0 0 1.5rem;
  font: 400 1.05rem/1.7 var(--pixel);
  color: var(--head);
}
main h3 { margin: 0 0 0.4rem; font: 400 0.7rem/1.6 var(--pixel); color: var(--head); }
main p, main ul, main dl { margin: 0 0 1.15rem; }
main ul { padding-left: 1.2rem; }
main li { margin-bottom: 0.45rem; }
main li::marker { color: var(--muted); }
main figure { margin: 2rem 0; }
.screen.small { max-width: 30rem; }

.pair { display: grid; grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr)); gap: 1.25rem; margin: 2rem 0; }
.pair figure { margin: 0; }

/* the four steps of a picture: a sequence, so numbered; the rule's colour says where it runs */
.pipeline {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: 1.75rem 2rem;
  margin: 2rem 0 2.25rem;
  padding: 0;
  list-style: none;
  counter-reset: step;
}
.pipeline li {
  position: relative;
  margin: 0;
  padding: 0.1rem 0 0 1.1rem;
  border-left: 4px solid var(--rp);
  counter-increment: step;
  font-size: 1rem;
  line-height: 1.6;
}
.pipeline li:nth-child(3) { border-color: var(--cart); }
.pipeline li:nth-child(4) { border-color: var(--st); }
.pipeline li p { margin: 0; }
.pipeline .where { margin-bottom: 0.3rem; font-size: 0.9rem; font-style: italic; color: var(--muted); }
.pipeline h3::before { content: counter(step) " "; color: var(--muted); }

/* the frame's budget, per machine */
.budget .machine { margin-bottom: 1.25rem; }
.m-name { margin: 0 0 0.4rem; font-weight: 650; color: var(--head); }
.m-name span { font-weight: 400; font-style: italic; color: var(--muted); }
.bar { height: 2.25rem; background: var(--deep); }
.bar span { position: relative; overflow: hidden; }
.bar i {
  position: absolute;
  inset: 0 auto 0 0.5rem;
  display: flex;
  align-items: center;
  font: italic 0.88rem/1 var(--serif);
  color: var(--space);
  white-space: nowrap;
}
.bar .t-spare i { left: auto; right: 0.5rem; }
.scale {
  display: flex;
  justify-content: space-between;
  margin-top: -0.6rem;
  font-size: 0.8rem;
  color: var(--muted);
  font-variant-numeric: lining-nums tabular-nums;
}

.signals { padding: 0; list-style: none; }
.signals li { padding-left: 1rem; border-left: 2px solid var(--cart); }
.signals span { font-weight: 650; color: var(--head); }

/* the frame-rate comparison */
.panes { display: grid; grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr)); gap: 1.25rem; }
.pane canvas {
  display: block;
  width: 100%;
  aspect-ratio: 4 / 3;
  image-rendering: pixelated;
  background: #000;
  border: 1px solid var(--rule);
}
.pane p { margin: 0.5rem 0 0; font-size: 0.95rem; line-height: 1.5; }
.play {
  margin-top: 1rem;
  padding: 0.45rem 0.9rem;
  font: 0.6rem/1.4 var(--pixel);
  color: var(--space);
  background: var(--head);
  border: 0;
  cursor: pointer;
}
.play:hover { background: #ffffff; }

.facts div { display: grid; grid-template-columns: minmax(0, 10rem) minmax(0, 1fr); gap: 1rem; padding: 0.7rem 0; border-top: 1px solid var(--rule); }
.facts div:last-child { border-bottom: 1px solid var(--rule); }
.facts dt { font-weight: 650; color: var(--head); }
.facts dd { margin: 0; }
@media (max-width: 30rem) { .facts div { grid-template-columns: 1fr; gap: 0.2rem; } }

.foot {
  padding: 2rem var(--gutter) 3rem;
  border-top: 1px solid var(--rule);
  font-size: 0.95rem;
  color: var(--muted);
}
.foot p { max-width: 76rem; margin: 0 auto; }

/* ---- the developer details ---- */

/* A cartridge DIP switch: a square knob in a chamfered track, sliding in pixel steps. The
   developer blocks share its colour, the RP2040's cyan. */
html[data-dev="off"] .dev { display: none; }

.dev-switch {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.25rem 0;
  font: 0.6rem/1.4 var(--pixel);
  color: var(--text);
  background: none;
  border: 0;
  cursor: pointer;
}
.dev-switch[hidden] { display: none; }
.dev-switch .track {
  position: relative;
  flex: none;
  width: 3.25rem;
  height: 1.625rem;
  background: var(--deep);
  box-shadow: inset 0 0 0 2px var(--rule);
  clip-path: polygon(2px 0, calc(100% - 2px) 0, calc(100% - 2px) 2px, 100% 2px,
    100% calc(100% - 2px), calc(100% - 2px) calc(100% - 2px), calc(100% - 2px) 100%,
    2px 100%, 2px calc(100% - 2px), 0 calc(100% - 2px), 0 2px, 2px 2px);
}
.dev-switch .knob {
  position: absolute;
  top: 4px;
  left: 4px;
  width: calc(1.625rem - 8px);
  height: calc(1.625rem - 8px);
  background: var(--muted);
  /* GEM's bevel: light on the top and left, shade on the bottom and right */
  box-shadow: inset 2px 2px 0 rgba(255, 255, 255, 0.45), inset -2px -2px 0 rgba(0, 0, 36, 0.45);
  transition: transform 160ms steps(4), background-color 160ms steps(2);
}
.dev-switch:hover .knob { background: var(--text); }
.dev-switch[aria-checked="true"] .track { background: #004992; box-shadow: inset 0 0 0 2px var(--rp); }
.dev-switch[aria-checked="true"] .knob {
  transform: translateX(1.625rem);
  background: var(--rp);
  box-shadow: inset 2px 2px 0 rgba(255, 255, 255, 0.6), inset -2px -2px 0 rgba(0, 36, 73, 0.5), 0 0 10px 2px rgba(109, 219, 255, 0.55);
}
.dev-switch[aria-checked="true"] .dev-label { color: var(--rp); }
@media (prefers-reduced-motion: reduce) { .dev-switch .knob { transition: none; } }

.more { margin: 2rem 0; padding: 1rem 1.15rem 1.1rem; background: var(--deep); border-left: 3px solid var(--rp); }
.more > :last-child { margin-bottom: 0; }
.more-label { margin: 0 0 0.75rem; font: 0.6rem/1.6 var(--pixel); color: var(--rp); }
.more pre { background: var(--space); }
html[data-dev="on"] .more { animation: dev-in 240ms steps(4); }
@keyframes dev-in { from { opacity: 0; } to { opacity: 1; } }
@media (prefers-reduced-motion: reduce) { html[data-dev="on"] .more { animation: none; } }

main pre {
  margin: 0 0 1.15rem;
  padding: 0.9rem 1rem;
  overflow-x: auto;
  background: var(--deep);
  border-left: 2px solid var(--rule);
  font: 0.86rem/1.55 ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  color: var(--text);
}
main pre code { font: inherit; color: inherit; }

.t { width: 100%; margin: 0 0 1.25rem; border-collapse: collapse; font-size: 0.95rem; line-height: 1.5; }
.t caption { margin-bottom: 0.5rem; text-align: left; font-style: italic; color: var(--muted); }
.t th { padding: 0.35rem 0.75rem 0.35rem 0; text-align: left; font-weight: 650; color: var(--head); border-bottom: 1px solid var(--muted); }
.t td { padding: 0.45rem 0.75rem 0.45rem 0; vertical-align: top; border-bottom: 1px solid var(--rule); overflow-wrap: anywhere; }
.t td:first-child { white-space: nowrap; }
@media (max-width: 30rem) { .t td:first-child { white-space: normal; } }