/* Split Expenses — a grayscale, mobile-first specimen sheet.
   Two typefaces: an old-style serif for reading, a mono for machine parts.
   No color, so hierarchy comes from size, weight, rules, and inversion. */

:root {
  --paper: #f3f3f3;
  --card: #fff;
  --ink: #121212;
  --ink-2: #3d3d3d;
  --ink-3: #6b6b6b;
  --ink-4: #9a9a9a;
  --rule: #d8d8d8;
  --rule-2: #e6e6e6;
  --bar: #b8b8b8;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, "Times New Roman", serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

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

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

body {
  margin: 0;
  min-width: 20rem;
  background-color: var(--paper);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='180' height='180'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='3' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='180' height='180' filter='url(%23n)' opacity='.05'/%3E%3C/svg%3E");
  background-size: 180px 180px;
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1rem;
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
}

::selection {
  background: var(--ink);
  color: var(--paper);
}

a {
  color: inherit;
}

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

h1,
h2 {
  margin: 0;
  font-weight: 400;
  letter-spacing: -0.028em;
  line-height: 1.02;
  text-wrap: balance;
}

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

/* ---------------------------------------------------------------- shell */

.wrap {
  width: min(100% - 2.5rem, 40rem);
  margin-inline: auto;
}

.skip-link {
  position: fixed;
  z-index: 20;
  top: 0.5rem;
  left: 0.5rem;
  padding: 0.75rem 1rem;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--mono);
  font-size: 0.75rem;
  text-decoration: none;
  transform: translateY(-200%);
}

.skip-link:focus {
  transform: none;
}

/* The rules run edge to edge; the type stays in its column. */
.masthead,
.chapter,
.site-footer {
  border-top: 1px solid var(--ink);
}

.masthead {
  border-top: 0;
  border-bottom: 1px solid var(--ink);
}

.masthead .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 1rem;
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
}

.wordmark svg {
  display: block;
  width: 1.25rem;
  height: 1.25rem;
  flex: none;
}

/* --------------------------------------------------------- micro labels */

.label,
.kicker,
.chapter-num,
.facts,
figcaption,
.route-label,
.btn,
.wordmark span,
.masthead nav a,
.fineprint,
.site-footer nav a {
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
  line-height: 1.5;
  text-transform: uppercase;
}

.kicker,
.chapter-num,
.masthead nav a,
.site-footer nav a {
  color: var(--ink-3);
}

.chapter-num .num,
.masthead nav a:hover,
.site-footer nav a:hover {
  color: var(--ink);
}

.chapter-num .num {
  margin-right: 0.5rem;
}

.masthead nav a,
.site-footer nav a {
  text-decoration: none;
}

.masthead nav a:hover,
.site-footer nav a:hover {
  text-decoration: underline;
  text-underline-offset: 0.3em;
}

.kicker::before {
  display: inline-block;
  width: 1.25rem;
  margin-right: 0.6rem;
  border-top: 1px solid var(--ink-4);
  content: "";
  vertical-align: 0.3em;
}

.fineprint {
  color: var(--ink-3);
  font-size: 0.625rem;
  letter-spacing: 0.14em;
  text-transform: none;
}

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

.hero {
  padding-block: 3rem 3.25rem;
}

.hero h1 {
  margin-block: 1.25rem;
  font-size: clamp(2rem, 10.5vw, 4rem);
}

.lede {
  max-width: 34rem;
  color: var(--ink-2);
  font-size: clamp(1.0625rem, 4.4vw, 1.25rem);
  line-height: 1.55;
}

.actions {
  display: grid;
  gap: 0.625rem;
  margin-top: 2rem;
}

.btn {
  display: inline-flex;
  align-items: baseline;
  justify-content: center;
  gap: 0.6rem;
  padding: 0.95rem 1.25rem;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: var(--paper);
  text-decoration: none;
  transition: background 0.15s ease, color 0.15s ease;
}

.btn .meta {
  opacity: 0.6;
  font-size: 0.625rem;
  letter-spacing: 0.14em;
}

.btn:hover {
  background: transparent;
  color: var(--ink);
}

.btn--quiet {
  background: transparent;
  color: var(--ink);
}

.btn--quiet:hover {
  background: var(--ink);
  color: var(--paper);
}

.facts {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 0.9rem;
  margin: 1.5rem 0 0;
  padding: 0;
  color: var(--ink-3);
  font-size: 0.625rem;
  letter-spacing: 0.16em;
  list-style: none;
}

.facts li + li::before {
  margin-right: 0.9rem;
  content: "·";
}

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

.chapter {
  padding-block: 3rem;
}

.chapter h2 {
  margin-block: 0.9rem 1rem;
  font-size: clamp(1.75rem, 7.5vw, 2.75rem);
}

.chapter p:not([class]) {
  max-width: 34rem;
  color: var(--ink-2);
}

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

.plate {
  max-width: 30rem;
  margin: 2.25rem 0 0;
}

figcaption {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 0.75rem;
  padding-top: 0.6rem;
  border-top: 1px solid var(--rule);
  color: var(--ink-3);
  font-size: 0.625rem;
  letter-spacing: 0.14em;
}

/* Only offered when a script is around to honour it. */
.replay {
  display: none;
}

.js .replay {
  display: inline-block;
  flex: none;
  padding: 0;
  border: 0;
  background: none;
  color: var(--ink);
  cursor: pointer;
  font: inherit;
  text-decoration: underline;
  text-underline-offset: 0.3em;
}

.fig {
  display: block;
  width: 100%;
  height: auto;
}

.fig text {
  fill: var(--ink);
  font-family: var(--mono);
}

.fig .say {
  fill: var(--ink);
  font-family: var(--serif);
  font-size: 14px;
  font-style: italic;
}

.fig .lab {
  fill: var(--ink-3);
  font-size: 8px;
  letter-spacing: 0.16em;
}

.fig .lab-ink {
  fill: var(--ink);
}

.fig .row {
  font-size: 10.5px;
}

.fig .meta {
  fill: var(--ink-3);
  font-size: 8.5px;
}

.fig .node {
  font-size: 9.5px;
  font-weight: 700;
}

.fig .tiny {
  fill: var(--ink-3);
  font-size: 7.5px;
}

.fig .hair {
  fill: none;
  stroke: var(--rule-2);
}

.fig .rule {
  fill: none;
  stroke: var(--ink);
}

.fig .faint {
  fill: none;
  stroke: var(--rule);
  stroke-width: 0.9;
}

.fig .wire {
  fill: none;
  stroke: var(--ink);
  stroke-width: 1.4;
}

.fig .head {
  fill: var(--ink);
}

.fig .axis {
  fill: none;
  stroke: var(--ink-4);
  stroke-dasharray: 1.5 3;
}

.fig .receipt {
  fill: none;
  stroke: var(--ink-3);
  stroke-width: 0.9;
}

.fig .receipt-line {
  fill: none;
  stroke: var(--ink-4);
  stroke-width: 0.8;
}

/* The sweep only ever exists mid-animation, so it starts and ends invisible. */
.fig .scan {
  opacity: 0;
  fill: none;
  stroke: var(--ink);
}

.fig .bar {
  transform-box: fill-box;
}

.fig .bar-pos {
  fill: var(--ink);
  transform-origin: 0% 50%;
}

.fig .bar-neg {
  fill: var(--bar);
  transform-origin: 100% 50%;
}

.fig .drawn {
  stroke-dasharray: var(--len);
}

/* Hidden only once we know a script can bring them back. */
.js .fig .anim {
  opacity: 0;
}

.js .fig .bar {
  transform: scaleX(0);
}

.js .fig .drawn {
  stroke-dashoffset: var(--len);
}

.is-playing .anim {
  animation: fig-rise 0.38s var(--d, 0s) cubic-bezier(0.2, 0.75, 0.3, 1) both;
}

.is-playing .bar {
  animation: fig-grow 0.55s var(--d, 0s) cubic-bezier(0.2, 0.8, 0.3, 1) both;
}

.is-playing .drawn {
  animation: fig-draw 0.45s var(--d, 0s) cubic-bezier(0.3, 0.8, 0.35, 1) both;
}

.is-playing .scan {
  animation: fig-scan 0.85s var(--d, 0s) ease-in-out both;
}

@keyframes fig-rise {
  from {
    opacity: 0;
    transform: translateY(6px);
  }

  to {
    opacity: 1;
    transform: none;
  }
}

@keyframes fig-grow {
  to {
    transform: scaleX(1);
  }
}

@keyframes fig-draw {
  to {
    stroke-dashoffset: 0;
  }
}

@keyframes fig-scan {
  0% {
    opacity: 0;
    transform: translateY(0);
  }

  18%,
  82% {
    opacity: 0.85;
  }

  100% {
    opacity: 0;
    transform: translateY(14px);
  }
}

/* -------------------------------------------------------------- install */

.routes {
  margin: 2rem 0 1.5rem;
  padding: 0;
  list-style: none;
}

.routes li {
  padding-block: 1.4rem;
  border-top: 1px solid var(--rule);
}

.route-label {
  margin-bottom: 0.35rem;
}

.routes p:not([class]) {
  color: var(--ink-2);
}

pre {
  overflow-x: auto;
  max-width: 34rem;
  margin: 1rem 0 0;
  padding: 0.85rem 1rem;
  border: 1px solid var(--rule);
  background: var(--card);
}

code {
  color: var(--ink);
  font-family: var(--mono);
  font-size: 0.8125rem;
  line-height: 1.7;
}

.routes .btn {
  margin-top: 1rem;
}

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

.site-footer .wrap {
  display: grid;
  gap: 1.25rem;
  padding-block: 2rem 2.5rem;
}

.site-footer nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1.25rem;
}

/* ------------------------------------------------------------ wide-open */

@media (min-width: 34rem) {
  .actions {
    grid-auto-flow: column;
    justify-content: start;
  }

  .btn {
    justify-content: flex-start;
  }

  .site-footer .wrap {
    grid-template-columns: auto 1fr;
    align-items: baseline;
    column-gap: 2rem;
  }

  .site-footer nav {
    justify-content: flex-end;
  }

  .site-footer .fineprint {
    grid-column: 1 / -1;
  }
}

@media (min-width: 48rem) {
  .hero {
    padding-block: 5rem 4.5rem;
  }

  .chapter {
    padding-block: 4.5rem;
  }
}

/* ------------------------------------------------------ reduced motion */

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

  .js .fig .anim {
    opacity: 1;
  }

  .js .fig .bar {
    transform: none;
  }

  .js .fig .drawn {
    stroke-dashoffset: 0;
  }

  .js .replay {
    display: none;
  }

  *,
  *::before,
  *::after {
    animation-delay: 0s !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}