/* moonmath — a manuscript on the arithmetic of space.
 *
 * One paper, three hands: EB Garamond for the reading, IM Fell English for the
 * headings, Caveat for what a reader would have written in the margin. The
 * colour is iron-gall ink on aged rag, with rubrication for the numbers.
 *
 * Two themes: the daylit page, and the same page read by candlelight. Everything
 * that has a colour is a variable, so the dark sheet is one block at the end.
 */

:root {
  --paper: #efe3c8;
  --paper-lift: #f7efdc;
  --paper-deep: #e4d3b2;
  --paper-plate: #e9dabd;
  --ink: #2a1d13;
  --ink-soft: #4a3625;
  --ink-faint: #7b6448;
  --rubric: #8f2d18;
  --rubric-soft: #a94a2d;
  --gilt: #9a7833;
  --rule: #bda884;
  --rule-faint: #d3c0a0;
  --slip: #f6ecd7;
  --slip-edge: #cbb693;
  --shadow: 24 16 8;
  --grain: 0.16;
  --grain-blend: multiply;
  --stain-a: rgb(150 106 52 / 12%);
  --stain-b: rgb(120 82 40 / 9%);
  --stain-c: rgb(90 60 28 / 6%);
  --selection: rgb(143 45 24 / 18%);

  --serif: "EB Garamond", "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --display: "IM Fell English", "EB Garamond", Georgia, serif;
  --small-caps: "IM Fell English SC", "IM Fell English", Georgia, serif;
  --hand: "Caveat", "Segoe Script", "Bradley Hand", cursive;
  --mono: "Courier Prime", "Courier New", Courier, monospace;

  --measure: 33rem;
  --rail: 19rem;
  --step: clamp(1.05rem, 0.6rem + 1.1vw, 1.22rem);
}

[data-theme="dark"] {
  --paper: #14100b;
  --paper-lift: #1d1710;
  --paper-deep: #0e0b07;
  --paper-plate: #191309;
  --ink: #ecdcc0;
  --ink-soft: #c9b694;
  --ink-faint: #9a8363;
  --rubric: #d97a4c;
  --rubric-soft: #b8613a;
  --gilt: #c9a25e;
  --rule: #4a3a29;
  --rule-faint: #33271b;
  --slip: #1b150e;
  --slip-edge: #3d3021;
  --shadow: 0 0 0;
  --grain: 0.1;
  --grain-blend: screen;
  --stain-a: rgb(217 122 76 / 7%);
  --stain-b: rgb(201 162 94 / 5%);
  --stain-c: rgb(0 0 0 / 30%);
  --selection: rgb(217 122 76 / 25%);
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 6rem;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--serif);
  font-size: var(--step);
  line-height: 1.74;
  font-variant-numeric: oldstyle-nums proportional-nums;
  background-color: var(--paper);
  background-image:
    radial-gradient(58rem 40rem at 12% 6%, var(--stain-a), transparent 70%),
    radial-gradient(46rem 38rem at 92% 22%, var(--stain-b), transparent 68%),
    radial-gradient(52rem 44rem at 70% 96%, var(--stain-c), transparent 72%),
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='320' height='320'%3E%3Cfilter id='g'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.82' numOctaves='4' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='320' height='320' filter='url(%23g)' opacity='0.34'/%3E%3C/svg%3E");
  background-attachment: fixed, fixed, fixed, scroll;
  background-blend-mode: normal, normal, normal, var(--grain-blend);
  background-size: auto, auto, auto, 320px 320px;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 4;
  pointer-events: none;
  opacity: var(--grain);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='320' height='320'%3E%3Cfilter id='g'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.82' numOctaves='4' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='320' height='320' filter='url(%23g)' opacity='0.34'/%3E%3C/svg%3E");
  background-size: 320px 320px;
  mix-blend-mode: var(--grain-blend);
}

/* Everything that is not paper sits above the grain. */
.masthead,
main,
.colophon,
.skip {
  position: relative;
  z-index: 5;
}

::selection {
  background: var(--selection);
}

/* ---------- the two hands, and the typed slips ---------- */

h1,
h2,
h3,
h4 {
  font-family: var(--display);
  font-weight: 400;
  line-height: 1.18;
  text-wrap: balance;
  margin: 0;
}

p {
  margin: 0 0 1.05em;
  text-wrap: pretty;
}

a {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px solid var(--rule);
  padding-bottom: 0.08em;
  transition:
    color 120ms ease,
    border-color 120ms ease;
}

a:hover {
  color: var(--rubric);
  border-bottom-color: var(--rubric);
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--rubric);
  outline-offset: 3px;
  border-radius: 1px;
}

code,
kbd,
samp,
pre {
  font-family: var(--mono);
  font-size: 0.9em;
  font-variant-ligatures: none;
  font-feature-settings: "liga" 0, "clig" 0, "calt" 0;
}

/* Form controls do not inherit, so they are told separately. */
button,
input,
textarea,
select {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
  font-variant-ligatures: no-contextual;
}

p code,
li code,
td code,
dd code,
.gloss code {
  background: color-mix(in srgb, var(--ink) 6%, transparent);
  border: 1px solid color-mix(in srgb, var(--rule) 55%, transparent);
  border-radius: 2px;
  padding: 0 0.28em;
  font-size: 0.86em;
  white-space: normal;
  overflow-wrap: anywhere;
}

em {
  font-style: italic;
}

strong {
  font-weight: 600;
}

.small-caps {
  font-family: var(--small-caps);
  letter-spacing: 0.06em;
}

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

.masthead {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(6px) saturate(120%);
  border-bottom: 1px solid var(--rule);
  box-shadow: 0 1px 0 color-mix(in srgb, var(--paper-lift) 70%, transparent) inset;
}

.masthead-inner {
  max-width: 70rem;
  margin: 0 auto;
  padding: 0.55rem clamp(1rem, 4vw, 2.6rem);
  display: flex;
  align-items: center;
  gap: clamp(0.8rem, 2.4vw, 2rem);
}

.mark {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  border: 0;
  flex: none;
  padding: 0.15rem 0;
}

.mark:hover {
  color: inherit;
}

.mark:hover .nib {
  color: var(--rubric);
}

.nib {
  width: 1.45rem;
  height: 1.45rem;
  color: var(--ink-soft);
  transition: color 160ms ease;
  flex: none;
}

.mark-name {
  font-family: var(--small-caps);
  font-size: 1.22rem;
  letter-spacing: 0.1em;
  line-height: 1;
  display: block;
}

.mark-sub {
  display: block;
  font-family: var(--hand);
  font-size: 0.86rem;
  line-height: 1.1;
  color: var(--ink-faint);
  letter-spacing: 0.01em;
  transform: rotate(-0.6deg);
  transform-origin: left center;
}

.nav {
  display: flex;
  align-items: center;
  gap: 0.1rem;
  margin-left: auto;
  flex-wrap: wrap;
}

.nav a {
  border: 0;
  padding: 0.32rem 0.62rem;
  font-family: var(--small-caps);
  font-size: 0.94rem;
  letter-spacing: 0.07em;
  color: var(--ink-soft);
  position: relative;
}

.nav a:hover {
  color: var(--rubric);
}

.nav a[aria-current="page"] {
  color: var(--ink);
}

.nav a[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 0.62rem;
  right: 0.62rem;
  bottom: 0.1rem;
  height: 2px;
  background: var(--rubric);
  border-radius: 2px;
}

.tools {
  display: flex;
  align-items: center;
  gap: 0.1rem;
  padding-left: 0.5rem;
  margin-left: 0.2rem;
  border-left: 1px solid var(--rule-faint);
}

.icon-btn {
  display: inline-grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  padding: 0;
  border: 0;
  background: none;
  color: var(--ink-soft);
  cursor: pointer;
  border-radius: 2px;
}

.icon-btn:hover {
  color: var(--rubric);
  background: color-mix(in srgb, var(--ink) 5%, transparent);
}

.icon-btn svg {
  width: 1.05rem;
  height: 1.05rem;
  display: block;
}

[data-theme="light"] .icon-moon,
[data-theme="dark"] .icon-sun {
  display: none;
}

.skip {
  position: absolute;
  left: 1rem;
  top: -3rem;
  padding: 0.4rem 0.8rem;
  background: var(--paper-lift);
  border: 1px solid var(--rule);
  font-family: var(--small-caps);
  letter-spacing: 0.08em;
  z-index: 40;
  transition: top 120ms ease;
}

.skip:focus {
  top: 0.6rem;
}

/* ---------- the page ---------- */

main {
  max-width: 70rem;
  margin: 0 auto;
  padding: 0 clamp(1rem, 4vw, 2.6rem) 4rem;
}

.page {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, var(--rail));
  gap: clamp(1.6rem, 4vw, 3.6rem);
  align-items: start;
  padding-top: clamp(1.6rem, 4vw, 3rem);
}

.page > .column {
  grid-column: 1;
  max-width: var(--measure);
  min-width: 0;
}

.page > .margin {
  grid-column: 2;
  position: sticky;
  top: 5.2rem;
  min-width: 0;
}

/* A marginal note, in a reader's hand. */
.note {
  font-family: var(--hand);
  font-size: 1.16rem;
  line-height: 1.32;
  color: var(--ink-soft);
  margin: 0 0 2rem;
  padding-left: 1.4rem;
  position: relative;
  transform: rotate(-0.5deg);
}

.note::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.4rem;
  width: 1rem;
  height: 1.6rem;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 26' fill='none' stroke='%237b6448' stroke-width='1.2' stroke-linecap='round'%3E%3Cpath d='M2 2c1.2 6.4 4.6 9.4 9.4 10.6'/%3E%3Cpath d='M8.6 9.8l3.4 2.8-4 1.2' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-size: contain;
  opacity: 0.75;
}

[data-theme="dark"] .note::before {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 26' fill='none' stroke='%239a8363' stroke-width='1.2' stroke-linecap='round'%3E%3Cpath d='M2 2c1.2 6.4 4.6 9.4 9.4 10.6'/%3E%3Cpath d='M8.6 9.8l3.4 2.8-4 1.2' stroke-linejoin='round'/%3E%3C/svg%3E");
}

.note b {
  font-weight: 600;
  color: var(--ink);
}

.note .sum {
  display: block;
  margin-top: 0.4rem;
  font-size: 1.05rem;
  color: var(--ink-faint);
}

/* ---------- the title page ---------- */

.title-page {
  text-align: center;
  padding: clamp(2rem, 7vw, 5rem) 0 clamp(1.4rem, 4vw, 3rem);
  max-width: 44rem;
  margin: 0 auto;
}

.title-page .imprint {
  font-family: var(--small-caps);
  letter-spacing: 0.42em;
  font-size: 0.82rem;
  color: var(--ink-faint);
  text-transform: uppercase;
  margin-bottom: 1.6rem;
}

.title-page h1 {
  font-size: clamp(2.5rem, 7vw, 4.4rem);
  line-height: 1.02;
  letter-spacing: -0.012em;
  margin: 0 0 1.1rem;
}

.title-page h1 .of {
  font-family: var(--hand);
  font-size: 0.44em;
  letter-spacing: 0.02em;
  color: var(--rubric);
  display: inline-block;
  transform: translateY(0.02em) rotate(-2deg);
  margin-right: 0.06em;
}

.title-page .standfirst {
  font-size: 1.06em;
  color: var(--ink-soft);
  max-width: 30rem;
  margin: 0 auto 1.8rem;
}

.ornament {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.9rem;
  color: var(--rule);
  margin: 1.6rem auto;
  max-width: 22rem;
}

.ornament::before,
.ornament::after {
  content: "";
  height: 1px;
  flex: 1;
  background: currentColor;
}

.ornament svg {
  width: 2.6rem;
  height: 0.9rem;
  flex: none;
  color: var(--gilt);
}

.epigraph {
  font-style: italic;
  color: var(--ink-soft);
  font-size: 1.02em;
  max-width: 26rem;
  margin: 0 auto 1.6rem;
  line-height: 1.55;
}

.epigraph cite {
  display: block;
  font-style: normal;
  font-family: var(--small-caps);
  font-size: 0.82rem;
  letter-spacing: 0.12em;
  color: var(--ink-faint);
  margin-top: 0.7rem;
}

.contents {
  margin: 2.2rem auto 0;
  max-width: 30rem;
  text-align: left;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  padding: 0.9rem 0;
  display: grid;
  gap: 0.18rem;
}

.contents a {
  display: grid;
  grid-template-columns: 2.4rem minmax(0, 1fr) auto;
  align-items: baseline;
  gap: 0.4rem;
  border: 0;
  padding: 0.22rem 0;
  color: var(--ink-soft);
}

.contents a:hover {
  color: var(--rubric);
}

.contents .num {
  font-family: var(--small-caps);
  letter-spacing: 0.1em;
  color: var(--rubric);
  font-size: 0.92rem;
}

.contents .what {
  font-size: 1.02rem;
}

.contents .what::after {
  content: "";
  display: inline-block;
  width: 100%;
  border-bottom: 1px dotted var(--rule);
  margin-left: 0.5em;
  transform: translateY(-0.28em);
}

.contents .where {
  font-family: var(--small-caps);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  color: var(--ink-faint);
  white-space: nowrap;
}

/* ---------- sections ---------- */

section {
  padding-top: clamp(1.6rem, 4vw, 2.8rem);
}

.sec-head {
  margin-bottom: 1.5rem;
}

.sec-head .kicker {
  font-family: var(--small-caps);
  font-size: 0.82rem;
  letter-spacing: 0.24em;
  color: var(--rubric);
  text-transform: uppercase;
  display: flex;
  align-items: center;
  gap: 0.7rem;
}

.sec-head .kicker::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--rule-faint);
}

.sec-head h2 {
  font-size: clamp(1.6rem, 3.2vw, 2.15rem);
  margin-top: 0.35rem;
  letter-spacing: -0.005em;
}

.sec-head p {
  color: var(--ink-soft);
  margin-top: 0.6rem;
  font-size: 0.98em;
}

h3.sub {
  font-size: 1.28rem;
  margin: 2.2rem 0 0.7rem;
  font-family: var(--display);
}

/* The first letter, rubricated. */
.dropcap {
  float: left;
  font-family: var(--display);
  font-size: 4.75em;
  line-height: 0.755;
  padding: 0.02em 0.09em 0 0;
  color: var(--rubric);
  text-shadow: 0 1px 0 color-mix(in srgb, var(--paper-lift) 80%, transparent);
}

.preamble {
  font-size: 1.04em;
}

.preamble::after {
  content: "";
  display: block;
  clear: both;
}

.lead {
  font-family: var(--display);
  font-size: 1.24em;
  line-height: 1.5;
  color: var(--ink);
  margin-bottom: 1.1rem;
}

/* ---------- mathematics ---------- */

.math-display {
  margin: 1.5rem 0;
  padding: 0;
  overflow-x: auto;
  overflow-y: hidden;
  color: var(--ink);
}

.katex-display {
  margin: 0.2em 0 !important;
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  padding-bottom: 0.15rem;
}

.katex {
  font-size: 1.08em;
}

.katex-display > .katex {
  font-size: 1.14em;
}

/* A derivation: numbered lines, a rule down the left, room in the margin. */
.working {
  margin: 1.6rem 0 1.9rem;
  padding: 1.1rem 0 0.4rem 0;
  border-top: 1px solid var(--rule);
  counter-reset: step;
  position: relative;
}

.working::before {
  content: "";
  position: absolute;
  left: -1.1rem;
  top: 1.4rem;
  bottom: 1rem;
  width: 1px;
  background: linear-gradient(var(--rule), transparent);
  display: none;
}

.working ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.62rem;
}

.working li {
  counter-increment: step;
  display: grid;
  grid-template-columns: 2.1rem minmax(0, 1fr);
  gap: 0.5rem;
  align-items: baseline;
  padding: 0.2rem 0;
}

.working li::before {
  content: "(" counter(step) ")";
  font-family: var(--display);
  font-size: 0.9rem;
  color: var(--rubric);
  letter-spacing: 0.04em;
  text-align: right;
  padding-right: 0.35rem;
  white-space: nowrap;
}

.working .step-body {
  min-width: 0;
}

/* The formulae of a derivation line up on the same left edge as its prose; a
   centred one would wander as the lines change length. */
.working .step-body .katex-display,
.working .step-body .katex-display > .katex {
  text-align: left;
}

.working li.tall::before {
  align-self: start;
  margin-top: 0.55rem;
}

.working .step-body > p {
  margin: 0.35rem 0 0;
  font-size: 0.92em;
  color: var(--ink-soft);
}

.working .why {
  font-family: var(--hand);
  font-size: 1.08rem;
  color: var(--rubric-soft);
  margin-left: 0.5rem;
  white-space: nowrap;
}

/* ---------- figures ---------- */

figure.plate {
  margin: 1.8rem 0;
  padding: 0;
}

figure.plate .plate-inner {
  max-width: 32rem;
  margin: 0 auto;
  background: color-mix(in srgb, var(--paper-plate) 72%, transparent);
  border: 1px solid var(--rule);
  border-radius: 1px;
  box-shadow:
    0 1px 0 color-mix(in srgb, var(--paper-lift) 65%, transparent) inset,
    0 10px 26px -22px rgb(var(--shadow) / 70%);
  padding: 1rem;
}

figure.plate svg {
  display: block;
  width: 100%;
  height: auto;
  color: var(--ink);
  overflow: visible;
}

figure.plate figcaption {
  font-family: var(--small-caps);
  font-size: 0.86rem;
  letter-spacing: 0.03em;
  color: var(--ink-soft);
  margin-top: 0.6rem;
  line-height: 1.45;
}

figure.plate figcaption .no {
  color: var(--rubric);
  letter-spacing: 0.09em;
  margin-right: 0.3em;
}

.ink {
  fill: none;
  stroke: currentColor;
  stroke-width: 1.1;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.ink-thin {
  fill: none;
  stroke: currentColor;
  stroke-width: 0.6;
  opacity: 0.55;
}

.ink-dash {
  fill: none;
  stroke: currentColor;
  stroke-width: 0.8;
  stroke-dasharray: 3 4;
  opacity: 0.6;
}

.ink-faint {
  fill: none;
  stroke: currentColor;
  stroke-width: 0.7;
  opacity: 0.28;
}

.ink-label {
  font-family: var(--display);
  font-style: italic;
  font-size: 14px;
  fill: currentColor;
  stroke: none;
}

.ink-hand {
  font-family: var(--hand);
  font-size: 16px;
  fill: currentColor;
  stroke: none;
  opacity: 0.8;
}

/* The sixteen floats, as a strip of memory. */
.mem-figure {
  margin: 1.6rem 0 1.4rem;
}

.mem-strip {
  display: grid;
  gap: 0.25rem;
  min-width: 0;
}

.mem-strip .braces {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  font-family: var(--display);
  font-style: italic;
  font-size: 0.82rem;
  color: var(--ink-soft);
  text-align: center;
}

.mem-strip .braces span {
  position: relative;
  padding-bottom: 0.3rem;
}

.mem-strip .braces span::after {
  content: "";
  position: absolute;
  left: 6%;
  right: 6%;
  bottom: 0;
  height: 4px;
  border: 1px solid var(--rule);
  border-bottom: 0;
}

.mem-strip .cells {
  display: grid;
  grid-template-columns: repeat(16, minmax(0, 1fr));
  border: 1px solid var(--rule);
  background: color-mix(in srgb, var(--paper-lift) 45%, transparent);
  overflow: hidden;
}

.mem-strip .cells span {
  font-family: var(--mono);
  font-size: 0.68rem;
  color: var(--ink-soft);
  text-align: center;
  padding: 0.42rem 0;
  border-right: 1px dotted var(--rule);
  min-width: 0;
}

.mem-strip .cells span:nth-child(4n) {
  border-right: 1px solid var(--rule);
}

.mem-strip .cells span:last-child {
  border-right: 0;
}

.mem-figure figcaption {
  font-family: var(--small-caps);
  font-size: 0.86rem;
  letter-spacing: 0.03em;
  color: var(--ink-soft);
  margin-top: 0.6rem;
  line-height: 1.45;
}

.mem-figure figcaption .no {
  color: var(--rubric);
  letter-spacing: 0.09em;
  margin-right: 0.3em;
}

/* ---------- tables ---------- */

.ledger {
  width: 100%;
  border-collapse: collapse;
  margin: 1.4rem 0;
  font-size: 0.95em;
  font-variant-numeric: tabular-nums;
}

.ledger caption {
  caption-side: top;
  text-align: left;
  font-family: var(--small-caps);
  font-size: 0.84rem;
  letter-spacing: 0.06em;
  color: var(--ink-faint);
  padding-bottom: 0.4rem;
}

.ledger th {
  text-align: left;
  font-family: var(--small-caps);
  font-weight: 400;
  letter-spacing: 0.07em;
  font-size: 0.9em;
  color: var(--ink-soft);
  padding: 0.35rem 0.7rem 0.35rem 0;
  border-bottom: 3px double var(--rule);
  white-space: nowrap;
}

.ledger td {
  padding: 0.42rem 0.7rem 0.42rem 0;
  border-bottom: 1px solid var(--rule-faint);
  vertical-align: baseline;
}

.ledger tr:last-child td {
  border-bottom: 0;
}

.ledger td.num {
  text-align: right;
  font-family: var(--mono);
  font-size: 0.86em;
}

.ledger code {
  background: none;
  border: 0;
  padding: 0;
}

/* ---------- code, as a slip pasted into the page ---------- */

.slip {
  margin: 1.3rem 0;
  background: var(--slip);
  border: 1px solid var(--slip-edge);
  border-radius: 1px;
  box-shadow:
    0 1px 0 color-mix(in srgb, var(--paper-lift) 70%, transparent) inset,
    0 12px 24px -22px rgb(var(--shadow) / 80%);
  overflow: hidden;
  min-width: 0;
}

.slip-head {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.3rem 0.7rem;
  border-bottom: 1px dotted var(--rule);
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.slip-head .label {
  flex: 1;
}

.copy {
  border: 0;
  background: none;
  color: var(--ink-faint);
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  cursor: pointer;
  padding: 0.1rem 0.2rem;
}

.copy:hover {
  color: var(--rubric);
}

.slip pre {
  margin: 0;
  padding: 0.85rem 1rem;
  overflow-x: auto;
  font-size: 0.8rem;
  line-height: 1.62;
  tab-size: 2;
  color: var(--ink);
}

.slip pre code {
  font-size: inherit;
  background: none;
  border: 0;
  padding: 0;
  white-space: pre;
}

.slip.output {
  background: color-mix(in srgb, var(--paper-deep) 45%, var(--slip));
}

.slip.output pre {
  font-size: 0.78rem;
  line-height: 1.7;
  color: var(--ink-soft);
}

/* A printed line is data, not something to retype: when it is longer than the
   slip it continues on the next line rather than disappearing off the edge. */
.slip.output pre code {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

.slip.output .slip-head {
  color: var(--ink-faint);
}

/* MoonBit, coloured by hand: comments, strings, numbers, keywords. */
.tok-c {
  color: var(--ink-faint);
  font-style: italic;
}
.tok-s {
  color: color-mix(in srgb, var(--rubric) 78%, var(--ink));
}
.tok-n {
  color: color-mix(in srgb, var(--gilt) 70%, var(--ink));
}
.tok-k {
  color: color-mix(in srgb, var(--ink) 72%, var(--rubric));
  font-weight: 700;
}
.tok-t {
  color: color-mix(in srgb, var(--ink-soft) 70%, var(--rubric));
}

/* ---------- notes set into the text ---------- */

.remark {
  border-left: 2px solid var(--rubric);
  border-radius: 0 2px 2px 0;
  padding: 0.55rem 0 0.55rem 1.1rem;
  margin: 1.5rem 0;
  color: var(--ink-soft);
  font-size: 0.96em;
}

.remark .tag {
  font-family: var(--small-caps);
  letter-spacing: 0.12em;
  font-size: 0.84rem;
  color: var(--rubric);
  display: block;
  margin-bottom: 0.25rem;
}

.remark p:last-child {
  margin-bottom: 0;
}

/* A hand-written jotting, for the one formula worth writing out by hand. */
.jot {
  font-family: var(--hand);
  font-size: 1.34rem;
  line-height: 1.35;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--rule-faint);
  padding: 0.2rem 0 0.6rem;
  margin: 1.4rem 0;
  transform: rotate(-0.4deg);
}

.jot .katex {
  font-size: 1.15em;
}

/* The end of the page, and the next one. */
.turn-page {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 0.2rem 1.2rem;
  align-items: center;
  border: 0;
  border-top: 3px double var(--rule);
  border-bottom: 1px solid var(--rule);
  padding: 1rem 0 1.1rem;
  margin-top: 1rem;
}

.turn-page:hover {
  color: var(--ink);
}

.turn-kicker {
  grid-column: 1;
  font-family: var(--small-caps);
  font-size: 0.8rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--rubric);
}

.turn-title {
  grid-column: 1;
  font-family: var(--display);
  font-size: clamp(1.2rem, 2.4vw, 1.45rem);
  line-height: 1.3;
  text-wrap: balance;
}

.turn-mark {
  grid-column: 2;
  grid-row: 1 / span 2;
  color: var(--ink-faint);
  transition:
    transform 180ms ease,
    color 180ms ease;
}

.turn-mark svg {
  width: 2.2rem;
  height: 1rem;
  display: block;
}

.turn-page:hover .turn-mark {
  transform: translateX(0.35rem);
  color: var(--rubric);
}

/* ---------- the lexicon ---------- */

.lexicon {
  display: grid;
  grid-template-columns: minmax(0, 14rem) minmax(0, 36rem);
  justify-content: center;
  gap: clamp(1.4rem, 4vw, 3.4rem);
  align-items: start;
  padding-top: 1.6rem;
}

.index-rail {
  position: sticky;
  top: 5rem;
  max-height: calc(100vh - 6.5rem);
  overflow-y: auto;
  padding-right: 0.6rem;
  font-size: 0.92rem;
}

.index-rail .rail-title {
  font-family: var(--small-caps);
  letter-spacing: 0.16em;
  font-size: 0.78rem;
  color: var(--ink-faint);
  text-transform: uppercase;
  padding-bottom: 0.4rem;
  border-bottom: 3px double var(--rule);
  margin-bottom: 0.5rem;
}

.index-rail a {
  display: block;
  border: 0;
  padding: 0.14rem 0;
  color: var(--ink-soft);
  line-height: 1.4;
}

.index-rail a:hover,
.index-rail a.here {
  color: var(--rubric);
}

.index-rail .group {
  margin: 0.85rem 0 0.2rem;
  font-family: var(--small-caps);
  letter-spacing: 0.1em;
  font-size: 0.76rem;
  color: var(--rubric);
  text-transform: uppercase;
}

.index-rail .sub {
  padding-left: 0.7rem;
  border-left: 1px solid var(--rule-faint);
  margin-left: 0.05rem;
}

.index-rail .sub a {
  font-size: 0.85rem;
  color: var(--ink-faint);
  font-family: var(--mono);
  letter-spacing: -0.01em;
  text-transform: none;
}

.lexicon-body {
  min-width: 0;
  max-width: 36rem;
}

.lex-intro {
  border-bottom: 1px solid var(--rule);
  padding-bottom: 1.4rem;
  margin-bottom: 1.4rem;
}

.lex-intro h1 {
  font-size: clamp(2rem, 4.6vw, 2.9rem);
}

.lex-intro p {
  color: var(--ink-soft);
  margin-top: 0.6rem;
  max-width: 34rem;
}

.group-head {
  margin: 2.6rem 0 1rem;
  display: flex;
  align-items: baseline;
  gap: 0.9rem;
  border-bottom: 3px double var(--rule);
  padding-bottom: 0.3rem;
}

.group-head h2 {
  font-size: 1.42rem;
  letter-spacing: 0.01em;
}

.group-head .count {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-faint);
  letter-spacing: 0.1em;
  margin-left: auto;
  white-space: nowrap;
}

.entry {
  padding: 1.15rem 0 1rem;
  border-bottom: 1px solid var(--rule-faint);
  scroll-margin-top: 5.5rem;
}

.entry:last-child {
  border-bottom: 0;
}

.entry h3 {
  font-size: 1.24rem;
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.entry h3 .kind {
  font-family: var(--mono);
  font-size: 0.66rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  border: 1px solid var(--rule-faint);
  border-radius: 2px;
  padding: 0.05rem 0.32rem;
  transform: translateY(-0.12rem);
}

.entry .decl {
  font-family: var(--mono);
  font-size: 0.79rem;
  line-height: 1.6;
  color: var(--ink-soft);
  background: color-mix(in srgb, var(--paper-deep) 40%, transparent);
  border-left: 2px solid var(--rule);
  border-radius: 0;
  padding: 0.42rem 0.7rem;
  margin: 0.5rem 0 0.75rem;
  overflow-x: auto;
  white-space: pre;
}

.entry .gloss {
  font-size: 0.98em;
}

.entry .gloss > p:last-child {
  margin-bottom: 0;
}

.entry .gloss ul {
  margin: 0.4rem 0 0.8rem;
  padding-left: 1.1rem;
}

.entry .gloss li {
  margin-bottom: 0.25rem;
}

.members {
  margin: 0.8rem 0 0;
  display: grid;
  gap: 0.3rem;
}

.members .row {
  display: grid;
  grid-template-columns: minmax(0, 11rem) minmax(0, 1fr);
  gap: 0.8rem;
  align-items: baseline;
  font-size: 0.94em;
}

.members .row .name {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--ink);
}

.members .row .doc {
  color: var(--ink-soft);
  font-size: 0.95em;
}

.members .label {
  font-family: var(--small-caps);
  letter-spacing: 0.14em;
  font-size: 0.76rem;
  color: var(--rubric);
  text-transform: uppercase;
  margin-top: 0.6rem;
}

.traits {
  margin: 0.9rem 0 0;
  font-size: 0.9em;
  color: var(--ink-faint);
}

.traits .label {
  font-family: var(--small-caps);
  letter-spacing: 0.12em;
  font-size: 0.8rem;
  color: var(--ink-faint);
  text-transform: uppercase;
  margin-right: 0.4rem;
}

.traits code {
  font-size: 0.84em;
  color: var(--ink);
  background: none;
  border: 0;
  padding: 0;
  margin-right: 0.15em;
}

.entry .methods {
  margin-top: 0.4rem;
  border-top: 1px dotted var(--rule-faint);
  padding-top: 0.3rem;
}

.entry .methods .entry {
  border-bottom: 0;
  padding: 0.7rem 0 0.2rem;
}

.entry .methods .entry h3 {
  font-family: var(--mono);
  font-size: 0.94rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.entry .methods .entry h3 .kind {
  display: none;
}

/* The compact index of the double-precision package. */
.second-hand .entry {
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--rule-faint);
}

.second-hand h3 {
  font-size: 1.05rem;
}

.second-hand .names {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--ink-soft);
  line-height: 1.9;
  word-spacing: 0.1em;
}

.second-hand .group-head + .names {
  margin-top: 0.6rem;
}

.second-hand .names span + span::before {
  content: " · ";
  color: var(--ink-faint);
}

/* ---------- the workshop ---------- */

.workshop {
  padding-top: 0.4rem;
}

.bench {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 16rem);
  gap: clamp(1.2rem, 3vw, 2.4rem);
  align-items: stretch;
  margin: 0 0 1.6rem;
}

.screen {
  position: relative;
  align-self: stretch;
  background: color-mix(in srgb, var(--paper-plate) 62%, transparent);
  border: 1px solid var(--rule);
  box-shadow:
    0 1px 0 color-mix(in srgb, var(--paper-lift) 60%, transparent) inset,
    0 20px 40px -34px rgb(var(--shadow) / 85%);
  aspect-ratio: 16 / 10;
  min-width: 0;
}

.screen canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.screen .stamp {
  position: absolute;
  left: 0.8rem;
  top: 0.55rem;
  font-family: var(--small-caps);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--ink-faint);
  pointer-events: none;
}

.screen .stamp.bad {
  color: var(--rubric);
  font-family: var(--mono);
  letter-spacing: 0.04em;
  text-transform: none;
  max-width: 90%;
  text-align: left;
}

.dials {
  display: grid;
  gap: 0.95rem;
  padding-top: 0.2rem;
}

.dial label {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-family: var(--small-caps);
  letter-spacing: 0.08em;
  font-size: 0.9rem;
  color: var(--ink-soft);
  gap: 0.5rem;
}

.dial .value {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--ink);
  letter-spacing: 0;
}

.dial input[type="range"] {
  width: 100%;
  margin: 0.35rem 0 0;
  appearance: none;
  height: 1.1rem;
  background: none;
  cursor: pointer;
}

.dial input[type="range"]::-webkit-slider-runnable-track {
  height: 1px;
  background: var(--rule);
}

.dial input[type="range"]::-moz-range-track {
  height: 1px;
  background: var(--rule);
}

.dial input[type="range"]::-webkit-slider-thumb {
  appearance: none;
  width: 0.72rem;
  height: 0.72rem;
  margin-top: -0.34rem;
  border-radius: 50%;
  background: var(--paper-lift);
  border: 1px solid var(--rubric);
  box-shadow: 0 0 0 2px color-mix(in srgb, var(--paper) 70%, transparent);
}

.dial input[type="range"]::-moz-range-thumb {
  width: 0.72rem;
  height: 0.72rem;
  border-radius: 50%;
  background: var(--paper-lift);
  border: 1px solid var(--rubric);
}

.readout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 17rem) minmax(0, 12rem);
  gap: clamp(1rem, 3vw, 2.4rem);
  align-items: start;
}

.matrix {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  max-width: 21rem;
  gap: 0.14rem 0.9rem;
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--ink-soft);
  font-variant-numeric: tabular-nums;
  padding: 0.6rem 0.7rem;
  border-left: 1px solid var(--rule);
  border-right: 1px solid var(--rule);
  position: relative;
}

.matrix::before,
.matrix::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  width: 6px;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
}

.matrix::before {
  left: 0;
  border-left: 1px solid var(--rule);
}

.matrix::after {
  right: 0;
  border-right: 1px solid var(--rule);
}

.matrix span {
  text-align: right;
}

.matrix span.hot {
  color: var(--rubric);
}

.readout-label {
  font-family: var(--small-caps);
  letter-spacing: 0.14em;
  font-size: 0.78rem;
  color: var(--ink-faint);
  text-transform: uppercase;
  margin-bottom: 0.4rem;
}

.readout-note {
  font-family: var(--mono);
  font-size: 0.74rem;
  line-height: 1.7;
  color: var(--ink-faint);
  margin: 0.55rem 0 0;
}

.readout-note b {
  color: var(--rubric);
  font-weight: 400;
}

.dial-note {
  font-family: var(--hand);
  font-size: 1.08rem;
  line-height: 1.35;
  color: var(--ink-faint);
  margin: 0.3rem 0 0;
}

.curve {
  min-width: 0;
}

.curve svg {
  display: block;
  width: 100%;
  height: auto;
  color: var(--ink);
  overflow: visible;
}

.curve .cap {
  font-family: var(--small-caps);
  font-size: 0.8rem;
  letter-spacing: 0.05em;
  color: var(--ink-faint);
  margin-top: 0.3rem;
}

.switch {
  display: flex;
  gap: 0.4rem;
  margin: 0.2rem 0 0.9rem;
}

.switch button {
  border: 1px solid var(--rule-faint);
  background: none;
  padding: 0.2rem 0.6rem;
  font-family: var(--small-caps);
  letter-spacing: 0.08em;
  font-size: 0.84rem;
  color: var(--ink-soft);
  cursor: pointer;
  border-radius: 2px;
}

.switch button[aria-pressed="true"] {
  border-color: var(--rubric);
  color: var(--rubric);
  background: color-mix(in srgb, var(--rubric) 7%, transparent);
}

/* ---------- colophon ---------- */

.colophon {
  border-top: 3px double var(--rule);
  margin-top: 3rem;
  padding: 1.6rem clamp(1rem, 4vw, 2.6rem) 2.6rem;
  background: color-mix(in srgb, var(--paper-deep) 30%, transparent);
}

.colophon-inner {
  max-width: 70rem;
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) minmax(0, auto);
  gap: 1.4rem 2.4rem;
  align-items: end;
  font-size: 0.9rem;
  color: var(--ink-soft);
}

.colophon .device {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  font-family: var(--small-caps);
  letter-spacing: 0.1em;
  font-size: 1rem;
  color: var(--ink);
}

.colophon .device svg {
  width: 1.15rem;
  height: 1.15rem;
  color: var(--rubric);
}

.colophon .fine {
  color: var(--ink-faint);
  font-size: 0.84rem;
  line-height: 1.55;
}

.colophon .links {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  font-family: var(--small-caps);
  letter-spacing: 0.08em;
  font-size: 0.86rem;
}

.colophon .links a {
  border: 0;
}

.colophon .folio {
  font-family: var(--small-caps);
  letter-spacing: 0.14em;
  color: var(--ink-faint);
  font-size: 0.82rem;
  text-align: right;
}

/* ---------- the scrollbar, in ink ---------- */

@supports not selector(::-webkit-scrollbar) {
  * {
    scrollbar-width: thin;
    scrollbar-color: color-mix(in srgb, var(--ink-faint) 55%, transparent) transparent;
  }
}

::-webkit-scrollbar {
  width: 11px;
  height: 11px;
}

::-webkit-scrollbar-track {
  background: color-mix(in srgb, var(--paper-deep) 40%, transparent);
}

::-webkit-scrollbar-thumb {
  background: color-mix(in srgb, var(--ink-faint) 50%, transparent);
  border: 3px solid transparent;
  background-clip: content-box;
  border-radius: 6px;
}

::-webkit-scrollbar-thumb:hover {
  background: color-mix(in srgb, var(--rubric) 55%, transparent);
  background-clip: content-box;
}

/* ---------- the narrow sheet ---------- */

@media (width <= 1100px) {
  .page {
    grid-template-columns: minmax(0, 1fr);
  }

  .page > .column {
    max-width: 42rem;
  }

  .page > .margin {
    grid-column: 1;
    position: static;
    max-width: 42rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr));
    gap: 1.2rem;
    padding-top: 0.5rem;
    border-top: 1px solid var(--rule-faint);
  }

  .note {
    margin-bottom: 0.6rem;
  }

  .bench {
    grid-template-columns: minmax(0, 1fr);
  }

  .dials {
    grid-template-columns: repeat(auto-fit, minmax(11rem, 1fr));
  }
}

@media (width <= 900px) {
  .lexicon {
    grid-template-columns: minmax(0, 1fr);
  }

  .index-rail {
    position: static;
    max-height: none;
    border-bottom: 1px solid var(--rule);
    padding-bottom: 0.8rem;
  }

  .index-rail .sub {
    display: none;
  }
}

@media (width <= 720px) {
  :root {
    --step: 1.02rem;
  }

  .masthead-inner {
    flex-wrap: wrap;
    gap: 0.4rem;
    padding-top: 0.45rem;
    padding-bottom: 0.4rem;
  }

  .mark-sub {
    display: none;
  }

  .nav {
    order: 3;
    width: 100%;
    margin-left: 0;
    justify-content: flex-start;
    overflow-x: auto;
  }

  @supports not selector(::-webkit-scrollbar) {
    .nav {
      scrollbar-width: none;
    }
  }

  .nav::-webkit-scrollbar {
    display: none;
  }

  .nav a {
    padding: 0.24rem 0.45rem;
    font-size: 0.88rem;
    white-space: nowrap;
  }

  .nav a[aria-current="page"]::after {
    left: 0.45rem;
    right: 0.45rem;
  }

  .tools {
    margin-left: auto;
  }

  .title-page h1 {
    font-size: clamp(2.1rem, 12vw, 3rem);
  }

  /* On a phone the slip is narrower than a line of code: let it continue on the
     next line rather than hide the end of every call. */
  .slip pre {
    padding-left: 1.8rem;
    text-indent: -0.8rem;
  }

  .slip pre code {
    white-space: pre-wrap;
    overflow-wrap: anywhere;
  }

  .contents a {
    grid-template-columns: 1.9rem minmax(0, 1fr);
  }

  .contents .where {
    display: none;
  }

  .readout {
    grid-template-columns: minmax(0, 1fr);
  }

  .members .row {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.1rem;
  }

  .entry .methods .entry h3 {
    font-size: 0.86rem;
  }

  .colophon-inner {
    grid-template-columns: minmax(0, 1fr);
  }

  .colophon .folio {
    text-align: left;
  }
}

@media (prefers-reduced-motion: reduce) {
  .note,
  .jot,
  .mark-sub {
    transform: none;
  }
}

/* The page scroll bar shows while the page moves or under the pointer and
   hides a moment after; it keeps its place, so nothing shifts. */
@supports selector(::-webkit-scrollbar) {
  html:not(.scrolling)::-webkit-scrollbar-thumb { background: transparent; border-color: transparent; box-shadow: none; }
}
@supports not selector(::-webkit-scrollbar) {
  html:not(.scrolling) { scrollbar-color: transparent transparent; }
}