/* Portway site. The two signal colours are the console's own: blue is what the
   agent sent (raw), teal is what crossed the network (wire). Keep that meaning;
   nothing else on the page is blue or teal. */

:root {
  color-scheme: dark;
  --ground: #0f1820;
  --panel: #14202a;
  --panel-2: #1a2834;
  --rule: #263846;
  --ink: #e3eaef;
  --ink-dim: #97a9b6;
  --raw: #6f9cf2;
  --zstd: #9d8ccc;
  --wire: #2cc3a3;
  --signal: #e6b54a;
  --focus: #9cc2ff;

  --sans: "Archivo", "Helvetica Neue", Arial, sans-serif;
  --mono: "Fragment Mono", ui-monospace, "SF Mono", Menlo, monospace;

  --measure: 66ch;
  --gutter: clamp(16px, 4vw, 40px);
  --wide: 1120px;
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--ground);
  color: var(--ink);
  font: 400 1.0625rem/1.6 var(--sans);
  font-variation-settings: "wdth" 100;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: inherit; text-decoration-color: color-mix(in srgb, currentColor 45%, transparent); text-underline-offset: 0.18em; }
a:hover { text-decoration-color: currentColor; }

:focus-visible { outline: 2px solid var(--focus); outline-offset: 3px; border-radius: 3px; }

code, pre, output, .bytes, [data-counter] {
  font-family: var(--mono);
  font-variant-numeric: tabular-nums;
  /* Fragment Mono joins -- into a dash; CLI flags must stay two hyphens. */
  font-variant-ligatures: none;
  font-feature-settings: "liga" 0, "calt" 0;
}
code { font-size: 0.9em; }
:is(p, li, dd) code:not(pre code) { white-space: nowrap; }

.skip {
  position: absolute; left: var(--gutter); top: -100px;
  padding: 8px 12px; background: var(--ink); color: var(--ground); z-index: 10;
}
.skip:focus { top: 12px; }

/* ---------- masthead ---------- */

.masthead {
  max-width: var(--wide);
  margin: 0 auto;
  padding: 20px var(--gutter);
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  /* The primary links and the switcher wrap as one group, so a narrow screen
     drops the whole group below the brand rather than centring the brand
     against a two-row group. */
  flex-wrap: wrap;
}
.brand {
  display: inline-flex; align-items: center; gap: 10px;
  text-decoration: none;
  font-weight: 700; font-size: 1.125rem;
  font-variation-settings: "wdth" 80;
  letter-spacing: 0.01em;
}
/* The mark is a round-topped gate with a road threading through it: the blue
   arch is the receiver, the teal road the small difference that crosses. It
   keeps the signal colours, so the road matches the wire series below. */
.brand svg { width: auto; height: 22px; }
.brand .arch { fill: var(--raw); }
.brand .road { fill: var(--wire); }
.masthead nav { display: flex; gap: clamp(12px, 3vw, 28px); font-size: 0.95rem; }
.masthead nav a { text-decoration: none; color: var(--ink-dim); }
.masthead nav a:hover { color: var(--ink); }

/* The primary links and the language switcher share the right-hand end of the
   masthead, and on a narrow screen they wrap together as one group. */
.masthead-end {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: flex-end;
  gap: 8px clamp(12px, 3vw, 28px);
  margin-left: auto;
}

/* A screen reader's copy of a label the eye reads from an icon. */
.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  margin: -1px; padding: 0; border: 0;
  overflow: hidden; clip-path: inset(50%);
  white-space: nowrap;
}

/* The language switcher is one control, not four more links competing with the
   primary ones: it shows the language in hand and opens to the rest. Last thing
   in the masthead, and the smallest. */
.masthead .lang { position: relative; }
.lang > summary {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 5px 7px;
  border: 1px solid transparent;
  border-radius: 6px;
  font-size: 0.85rem;
  color: var(--ink-dim);
  cursor: pointer;
  list-style: none;
}
.lang > summary::-webkit-details-marker { display: none; }
.lang > summary:hover { color: var(--ink); background: var(--panel); }
.lang[open] > summary { color: var(--ink); background: var(--panel); border-color: var(--rule); }
.lang .globe { width: 14px; height: 14px; flex: none; }
.lang .caret { width: 9px; height: 6px; flex: none; transition: transform 120ms ease; }
.lang[open] .caret { transform: rotate(180deg); }

.masthead .lang-menu {
  position: absolute; top: calc(100% + 6px); right: 0; z-index: 20;
  display: grid; gap: 2px;
  min-width: 8.5rem;
  padding: 4px;
  font-size: 0.875rem;
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: 8px;
  box-shadow: 0 10px 24px rgb(0 0 0 / 45%);
}
.masthead .lang-menu a {
  display: flex; align-items: baseline; justify-content: space-between; gap: 10px;
  padding: 7px 10px;
  border-radius: 5px;
  text-decoration: none;
}
.masthead .lang-menu a:hover { background: var(--panel-2); color: var(--ink); }
.masthead .lang-menu a[aria-current] { color: var(--ink); }
.masthead .lang-menu a[aria-current]::after { content: "✓"; color: var(--ink-dim); }

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

.hero {
  max-width: var(--wide);
  margin: 0 auto;
  padding: clamp(16px, 4vw, 48px) var(--gutter) clamp(32px, 4vw, 48px);
}
.hero-copy { max-width: 58rem; }
.hero h1 { max-width: none; }
.hero-copy:lang(ko) { word-break: keep-all; }
.hero h1 span { display: inline-block; }

h1 {
  margin: 0;
  font-size: clamp(2.5rem, 1.3rem + 4.2vw, 4.25rem);
  line-height: 0.98;
  font-weight: 760;
  font-variation-settings: "wdth" 68;
  letter-spacing: -0.012em;
  text-wrap: balance;
  max-width: 12.5em;
}

.lede {
  margin: 1.4rem 0 0;
  max-width: 54ch;
  font-size: clamp(1.0625rem, 1rem + 0.35vw, 1.25rem);
  color: var(--ink-dim);
}

.actions { display: flex; flex-wrap: wrap; gap: 12px; margin: 2rem 0 0; }
.button {
  display: inline-block;
  padding: 11px 18px;
  border: 1px solid var(--rule);
  border-radius: 6px;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.975rem;
  background: var(--panel);
}
.button:hover { border-color: var(--ink-dim); }
.button.primary { background: var(--ink); color: var(--ground); border-color: var(--ink); }
.button.primary:hover { background: #fff; }

.hero-install { margin-top: 1.5rem; max-width: 36rem; }
.install-command {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 6px 6px 6px 16px;
  background: var(--panel);
  border: 1px solid var(--ink-dim);
  border-radius: 8px;
}
.install-command code {
  flex: 1;
  min-width: 0;
  font-size: 0.9375rem;
  white-space: normal;
  overflow-wrap: anywhere;
  user-select: all;
}
.install-command code::selection { background: var(--ink); color: var(--ground); }
.copy-command {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: none;
  gap: 8px;
  min-height: 44px;
  padding: 10px 12px;
  border: 1px solid var(--ink);
  border-radius: 4px;
  background: var(--ink);
  color: var(--ground);
  font: 600 0.875rem var(--sans);
  cursor: pointer;
}
.copy-command[hidden] { display: none; }
.copy-command:hover { background: #fff; }
.copy-command[aria-busy="true"] { cursor: wait; opacity: 0.7; }
.copy-command svg { width: 16px; height: 16px; flex: none; }
.install-note, .install-links, .copy-status {
  margin: 8px 0 0;
  color: var(--ink-dim);
  font-size: 0.875rem;
}
.copy-status:empty { display: none; }
.copy-status:not(.sr-only) { color: var(--signal); }
.install-links { display: flex; flex-wrap: wrap; gap: 8px 24px; }
.install-links a { display: inline-flex; align-items: center; min-height: 44px; color: var(--ink); }
.steps .command-block { margin-bottom: 1rem; }
.steps { margin: 2rem 0; padding-left: 1.5rem; }
.steps > li { padding-left: 8px; margin-bottom: 2rem; }
.steps > li::marker { color: var(--ink-dim); font-family: var(--mono); }
.steps p { margin: 0 0 1rem; }
.steps p.copy-status { margin: 8px 0 0; }
.steps code:not(pre code) { white-space: normal; overflow-wrap: anywhere; }

/* The monitor: an interface-counter graph of one real session. */

.monitor {
  margin: clamp(32px, 4.5vw, 52px) 0 0;
  padding: clamp(16px, 2.4vw, 28px);
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: 10px;
}
.monitor-head {
  display: flex; flex-wrap: wrap; align-items: flex-start; justify-content: space-between;
  gap: 16px 32px;
}
.monitor figcaption { max-width: 52ch; color: var(--ink-dim); font-size: 0.95rem; }
.monitor figcaption strong { color: var(--ink); font-weight: 600; }

.views { display: inline-flex; border: 1px solid var(--rule); border-radius: 6px; padding: 2px; background: var(--ground); }
.views button {
  font: 500 0.875rem var(--sans);
  color: var(--ink-dim);
  background: none; border: 0; border-radius: 4px;
  padding: 6px 12px; cursor: pointer;
}
.views button[aria-pressed="true"] { background: var(--panel-2); color: var(--ink); }

.readout {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 24px 0 8px;
}
.readout .series { border-top: 3px solid; padding-top: 10px; }
.readout .raw { border-color: var(--raw); }
.readout .zstd { border-color: var(--zstd); border-top-style: dashed; }
.readout .wire { border-color: var(--wire); }
.readout dt { font-size: 0.875rem; color: var(--ink-dim); }
.readout dd {
  margin: 2px 0 0;
  font-size: clamp(1rem, 0.8rem + 1.1vw, 1.625rem);
  letter-spacing: -0.01em;
  white-space: nowrap;
}
.readout .wire dd { color: var(--wire); }

.plot { position: relative; width: 100%; height: clamp(220px, 34vw, 360px); margin-top: 8px; }
.plot svg { display: block; width: 100%; height: 100%; overflow: visible; }
.plot .grid line { stroke: var(--rule); stroke-width: 1; }
.plot .tick { fill: var(--ink-dim); font: 11px var(--mono); }
.plot .raw-area { fill: color-mix(in srgb, var(--raw) 18%, transparent); }
.plot .raw-line { fill: none; stroke: var(--raw); stroke-width: 2; }
.plot .raw-bar { fill: color-mix(in srgb, var(--raw) 55%, transparent); }
.plot .zstd-line { fill: none; stroke: var(--zstd); stroke-width: 2; stroke-dasharray: 6 5; }
.plot .wire-line { fill: none; stroke: var(--wire); stroke-width: 3; stroke-linejoin: round; }
.plot .cursor { stroke: var(--ink); stroke-width: 1; stroke-dasharray: 2 3; opacity: 0.7; }
.plot .wire-dot { fill: var(--wire); stroke: var(--panel); stroke-width: 2; }
.plot .wire-label {
  fill: var(--wire);
  font: 12px var(--mono);
  paint-order: stroke;
  stroke: var(--panel);
  stroke-width: 5px;
  stroke-linejoin: round;
}
.plot-fallback { color: var(--ink-dim); }

.scrub {
  display: grid;
  grid-template-columns: auto auto 1fr;
  align-items: center;
  gap: 16px;
  margin-top: 16px;
}
.scrub label { font-size: 0.9rem; color: var(--ink-dim); white-space: nowrap; }
.scrub output { color: var(--ink); display: inline-block; min-width: 2ch; text-align: right; }
.replay {
  font: 600 0.875rem var(--sans);
  color: var(--ink);
  background: var(--panel-2);
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 7px 14px;
  cursor: pointer;
}
.replay:hover { border-color: var(--ink-dim); }
input[type="range"] { width: 100%; accent-color: var(--wire); margin: 0; }

.turn-note { margin: 12px 0 0; font-size: 0.9rem; color: var(--ink-dim); min-height: 1.6em; }
.turn-note b { color: var(--ink); font-weight: 600; font-family: var(--mono); font-size: 0.95em; }
.turn-note .w { color: var(--wire); }

/* ---------- screens ---------- */

/* The dashboards on a real session: one screen at a time, each linked to
   itself at full size. They are pictures, so their colours are their own. */
.chapter.screens { max-width: var(--wide); }
.chapter.screens > p { max-width: var(--measure); }
.screen { margin: 28px 0 0; }
.screen .views { margin-bottom: 14px; }
.screen .shot {
  display: block;
  border: 1px solid var(--rule);
  border-radius: 10px;
  overflow: hidden;
  background: var(--panel);
  box-shadow: 0 28px 64px -28px rgb(0 0 0 / 70%);
}
.screen .shot[hidden] { display: none; }
.screen img { display: block; width: 100%; height: auto; }

/* ---------- chapters ---------- */

.chapter {
  max-width: calc(var(--measure) + 2 * var(--gutter));
  margin: 0 auto;
  padding: clamp(56px, 8vw, 104px) var(--gutter) 0;
}
.chapter > p { margin: 0 0 1.1em; }

h2 {
  margin: 0 0 1.25rem;
  font-size: clamp(1.75rem, 1.2rem + 2.2vw, 2.75rem);
  line-height: 1.05;
  font-weight: 720;
  font-variation-settings: "wdth" 72;
  letter-spacing: -0.008em;
  text-wrap: balance;
}
h3 {
  margin: 2.5rem 0 1rem;
  font-size: 1.25rem;
  font-weight: 650;
  font-variation-settings: "wdth" 85;
}

.aside { color: var(--ink-dim); font-size: 0.95rem; }

.fit { margin: 0 0 1.25em; padding-left: 1.2em; }
.fit li { margin: 0.35em 0; }
.fit li::marker { color: var(--raw); }

/* What each request carries: strips drawn to scale. */

.strips { margin: 2rem 0 2.25rem; }
.strips figcaption { font-size: 0.9rem; color: var(--ink-dim); margin-bottom: 14px; }
.strip-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.strip-list li {
  display: grid;
  grid-template-columns: 4.5rem 1fr 6.5rem;
  align-items: center;
  gap: 12px;
  font-size: 0.85rem;
}
.strip-list .t { color: var(--ink-dim); white-space: nowrap; }
.strip-list .n { font-family: var(--mono); text-align: right; color: var(--ink-dim); font-variant-numeric: tabular-nums; }
.strip-list .bar { display: flex; height: 14px; }
.strip-list .old { background: color-mix(in srgb, var(--raw) 22%, var(--panel)); border-radius: 2px 0 0 2px; }
.strip-list .new { background: var(--raw); min-width: 3px; border-radius: 0 2px 2px 0; }
.strip-list .gap { color: var(--ink-dim); text-align: center; letter-spacing: 0.3em; }

/* The hop diagram. */

.hops { margin: 2rem 0 0; }
.hop-list {
  list-style: none; margin: 0; padding: 0;
  display: grid;
  grid-template-columns: 1fr;
}
.hops .node {
  padding: 12px 14px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--panel);
}
.node-name { display: block; font-weight: 650; font-variation-settings: "wdth" 85; }
.node-sub { display: block; font-size: 0.85rem; color: var(--ink-dim); }
.hops .link {
  position: relative;
  display: flex; align-items: center; gap: 14px;
  min-height: 52px;
  padding-left: 36px;
}
.hops .link::before {
  content: "";
  position: absolute; left: 20px; top: 0; bottom: 0;
  border-left: 2px solid var(--raw);
}
.hops .link.slow::before { border-left: 3px dashed var(--wire); left: 19px; }
.hops .bytes { font-size: 0.95rem; color: var(--raw); }
.hops .slow .bytes { color: var(--wire); font-size: 1.05rem; }
.link-sub { font-size: 0.85rem; color: var(--ink-dim); }
.hops figcaption { margin-top: 14px; font-size: 0.9rem; color: var(--ink-dim); }

/* Sequences: only where the content really is one. */

.steps { list-style: none; counter-reset: step; margin: 0; padding: 0; }
.steps > li {
  counter-increment: step;
  position: relative;
  padding: 0 0 0 2.75rem;
  margin: 0 0 1.5rem;
}
.steps > li::before {
  content: counter(step);
  position: absolute; left: 0; top: 0.05rem;
  width: 1.75rem; height: 1.75rem;
  display: grid; place-items: center;
  border: 1px solid var(--rule);
  border-radius: 50%;
  font: 500 0.85rem var(--mono);
  color: var(--ink-dim);
}
.steps p { margin: 0 0 0.75rem; }

/* RFC-style frame diagram. The ASCII is the figure; do not reflow it. */

.rfc { margin: 2rem 0 0; }
.rfc pre {
  margin: 0;
  padding: 18px 20px;
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: 8px;
  overflow-x: auto;
  font: 13px/1.45 var(--mono);
  color: var(--ink-dim);
}
.rfc pre b { color: var(--ink); font-weight: 400; }
.rfc pre i { color: var(--wire); font-style: normal; }
.rfc .ruler { color: color-mix(in srgb, var(--ink-dim) 70%, transparent); }
.rfc figcaption { margin-top: 12px; font-size: 0.9rem; color: var(--ink-dim); }

/* Fallback ladder. */

.ladder { list-style: none; counter-reset: rung; margin: 1.75rem 0 1.75rem; padding: 0; }
.ladder li {
  counter-increment: rung;
  display: grid;
  grid-template-columns: 2rem 1fr;
  grid-template-areas: "n rung" "n why";
  column-gap: 12px;
  padding: 14px 0;
  border-top: 1px solid var(--rule);
}
.ladder li:last-child { border-bottom: 1px solid var(--rule); }
.ladder li::before {
  content: counter(rung);
  grid-area: n;
  font: 500 0.95rem var(--mono);
  color: var(--ink-dim);
}
.ladder .rung { grid-area: rung; font-weight: 600; }
.ladder .why { grid-area: why; font-size: 0.9rem; color: var(--ink-dim); }
.status {
  color: var(--signal);
  font-size: 0.9em;
  padding: 0 0.3em;
  border: 1px solid color-mix(in srgb, var(--signal) 40%, transparent);
  border-radius: 3px;
}

/* Measured table. */

.table-wrap { overflow-x: auto; margin: 1.75rem 0 1.25rem; }
table { border-collapse: collapse; width: 100%; font-size: 0.95rem; }
caption { text-align: left; color: var(--ink-dim); font-size: 0.9rem; padding-bottom: 10px; }
th, td { padding: 10px 12px; border-bottom: 1px solid var(--rule); white-space: nowrap; }
thead th { font-weight: 600; text-align: right; color: var(--ink-dim); font-size: 0.85rem; vertical-align: bottom; }
thead th:first-child, tbody th { text-align: left; }
tbody th { font-weight: 600; }
td { text-align: right; font-family: var(--mono); font-variant-numeric: tabular-nums; }
td.w { color: var(--wire); }

pre.shell {
  margin: 0 0 1rem;
  padding: 14px 16px;
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: 8px;
  overflow-x: auto;
  font: 14px/1.55 var(--mono);
}
pre.shell code { font-size: inherit; }

/* Limits. */

.limits { margin: 0; display: grid; gap: 1.5rem; }
.limits dt { font-weight: 650; font-size: 1.0625rem; }
.limits dd { margin: 0.25rem 0 0; color: var(--ink-dim); }

.docs {
  list-style: none; margin: 2rem 0 0; padding: 0;
  display: flex; flex-wrap: wrap; gap: 8px 24px;
}

/* ---------- footer ---------- */

.colophon {
  max-width: calc(var(--measure) + 2 * var(--gutter));
  margin: clamp(72px, 10vw, 128px) auto 0;
  padding: 28px var(--gutter) 48px;
  border-top: 1px solid var(--rule);
  font-size: 0.9rem;
  color: var(--ink-dim);
}
.colophon p { margin: 0 0 0.4rem; }

/* ---------- other languages ---------- */

/* Archivo and Fragment Mono carry no CJK glyphs, so Korean, Japanese and
   Chinese fall through to whatever the reader has installed. Naming the fonts
   per language matters: Han characters are shared between the three, but their
   forms are not, and a Japanese page drawn in a Korean font shows Chinese
   shapes. The language is the page's, declared on <html>, so these are :lang()
   rules rather than classes the markup has to carry. */
html:lang(ko) {
  --sans: "Archivo", "Pretendard", "Apple SD Gothic Neo", "Noto Sans KR", "Nanum Gothic", "Malgun Gothic", "Helvetica Neue", Arial, sans-serif;
  --mono: "Fragment Mono", "D2Coding", ui-monospace, "SF Mono", Menlo, monospace;
}
html:lang(ja) {
  --sans: "Archivo", "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", "Noto Sans JP", "Meiryo", "Helvetica Neue", Arial, sans-serif;
  --mono: "Fragment Mono", "Hiragino Kaku Gothic ProN", ui-monospace, "SF Mono", Menlo, monospace;
}
html:lang(zh-Hans) {
  --sans: "Archivo", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", "Helvetica Neue", Arial, sans-serif;
  --mono: "Fragment Mono", "PingFang SC", ui-monospace, "SF Mono", Menlo, monospace;
}

/* The display sizes are set for Latin: condensed, tightly leaded, negatively
   tracked. CJK is none of those — a line-height under 1 crowds full-width
   glyphs, and tracking pulls them apart — so the headings get their own box.
   Wider, too, since a CJK character is a full em where a Latin one is nearer
   half of one. */
:is(html:lang(ko), html:lang(ja), html:lang(zh-Hans)) :is(h1, h2) {
  line-height: 1.2;
  letter-spacing: normal;
}
:is(html:lang(ko), html:lang(ja), html:lang(zh-Hans)) h1 { max-width: 17em; }

/* Korean headings break between words, never inside one, and the phrase
   spans in the markup pick the line breaks so a heading reads in beats:
   "40턴은 / 39턴 더하기 / 4킬로바이트". */
html:lang(ko) :is(h1, h2, h3) { word-break: keep-all; }
html:lang(ko) h2 span { display: inline-block; }

/* ---------- narrow screens ---------- */

@media (max-width: 640px) {
  .readout { grid-template-columns: 1fr; gap: 10px; }
  .readout .series { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; }
  .scrub { grid-template-columns: auto 1fr; }
  .scrub input { grid-column: 1 / -1; }
  .strip-list li { grid-template-columns: 3.25rem 1fr 5.25rem; gap: 8px; font-size: 0.8rem; }
  .rfc pre { font-size: 11px; padding: 14px; }
}

@media (min-width: 900px) {
  /* The topology reads left to right, so it breaks out of the text column. */
  .hops { margin-inline: calc(50% - min(530px, 50vw - var(--gutter))); }
  .hop-list {
    grid-template-columns: 1fr 0.85fr 1fr 0.85fr 1fr 0.85fr 1fr;
    align-items: stretch;
  }
  .hops .link {
    flex-direction: column; justify-content: center; align-items: center;
    gap: 20px;
    min-height: 0;
    padding: 0 10px;
    text-align: center;
  }
  .hops .link::before {
    left: 0; right: 0; top: 50%; bottom: auto;
    border-left: 0;
    border-top: 2px solid var(--raw);
  }
  .hops .link.slow::before { left: 0; border-left: 0; border-top: 3px dashed var(--wire); }
  .hops figcaption { max-width: 60ch; margin-inline: auto; text-align: center; }
}

@media (min-width: 1100px) {
  /* The cover: copy on the left, the monitor on the right, centred on each
     other so neither column trails off into empty space. */
  .hero {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    align-items: center;
    gap: 48px;
  }
  .hero-copy { max-width: none; }
  /* CJK glyphs are full-width, so in a 500px column the display size has to
     come down for a phrase to still fit on one line. */
  :is(html:lang(ko), html:lang(ja), html:lang(zh-Hans)) .hero h1 {
    font-size: clamp(2.5rem, 1rem + 3vw, 3.5rem);
  }
  .hero .monitor { margin-top: 0; padding: 20px; }
  .hero .monitor-head { gap: 16px; }
  .hero .readout { grid-template-columns: 1fr; gap: 10px; }
  .hero .readout .series { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; }
  .hero .readout dd { font-size: 1.125rem; }
  .hero .plot { height: 220px; }
  .hero .scrub { grid-template-columns: auto 1fr; }
  .hero .scrub input { grid-column: 1 / -1; }

  /* The chapters share the cover's container and its two-column rhythm: the
     heading sits in the left column, the prose in the right. The heading is
     not sticky on purpose; the hops figure spans both columns and a sticky
     heading would slide over it. */
  .chapter, .colophon {
    max-width: var(--wide);
    display: grid;
    grid-template-columns: minmax(0, 2fr) minmax(0, 3fr);
    column-gap: 48px;
    align-items: start;
  }
  .chapter > h2 { grid-column: 1; margin: 0; }
  .chapter > :not(h2), .colophon > p { grid-column: 2; }
  /* The topology still reads left to right across the whole width. */
  .chapter > .hops { grid-column: 1 / -1; margin-inline: 0; }
  .chapter > .screen { grid-column: 1 / -1; }
  /* In the heading column a Korean heading takes one phrase per line. */
  html:lang(ko) .chapter h2 span { display: block; }
}

@media (prefers-reduced-motion: reduce) {
  * { scroll-behavior: auto !important; }
}