/* variables */
:root {
	--font-size: 12pt;
	--line-height: 1.625;
  --font-family: monospace;

  /* font-derived vertical and horizontal units */
  --v-un: calc(var(--font-size) * var(--line-height));
  --h-un: 1ch;

  /* font-derived column width */
  --col-w: clamp(33.33vw, 80ch, 100vw);

  /* colors */
  --fg-c: #000000;
  --bg-c: #e2e2e2;
	--link-c: #856cff;
	--visited-c: #ff1170;
	--active-c: #fa3500;
}

@media (prefers-color-scheme: dark) {
  :root {
    --fg-c: #e2e2e2;
    --bg-c: #000000;
  }
}

/* reset */
* {
	box-sizing: border-box;
  margin: unset;
  hyphens: auto;
}

::selection {
  color: var(--bg-c);
  background-color: var(--fg-c);
}

/* root */
:root {
	color: var(--fg-c);
	background-color: var(--bg-c);
  font: var(--font-size)/var(--line-height) var(--font-family);
  scrollbar-width: thin;
  scrollbar-color: var(--link-c) rgba(0,0,0,0);
}

body {
  margin: 0;
}

/* content sectioning */
address {
  font-style: unset;
}

h1, h2, h3, h4, h5, h6 {
	font-size: unset;
}

h1, h2 {
  font-weight: bold;
}

h3, h4, h5, h6 {
  font-style: italic;
}

/* text content */

:is(h1, h2, h3, h4, h5, h6) {
  margin-block-start: calc(2 * var(--v-un));
  margin-block-end: var(--v-un);
}

:is(blockquote, div, dl, figure, hr, menu, ol, p, pre, ul) +
:is(blockquote, div, dl, figure, hr, menu, ol, p, pre, ul) {
  margin-block-start: var(--v-un);
}

blockquote {
	margin-inline: calc(4 * var(--h-un));
}

dt {
  font-style: italic;
}

dd {
  padding-inline-start: calc(4 * var(--h-un));
}

ol, ul, menu {
  padding-inline-start: calc(4 * var(--h-un));
}

:is(ol, ul, menu) :is(ol, ul, menu) {
  margin-block: unset;
}

li :is(blockquote, div, dl, figure, hr, menu, ol, p, pre, ul) {
  margin-block: unset;
}

ul>li::marker {
	content: "- ";
}

hr {
	color: unset;
	border: unset;
  text-align: center;
}

hr:after {
  content: "---";
}

pre {
  margin-inline: calc(4 * var(--h-un));
  color: var(--link-c);
  overflow-y: scroll;
}


/* inline text semantics */
a {
  cursor: pointer;
  text-decoration: underline;
}

a:link {
  color: var(--link-c);
}

a:link:active {
  color: var(--active-c);
}

a:visited {
  color: var(--visited-c);
}

a:visited:active {
  color: var(--active-c);
}

code {
  color: var(--link-c);
}

/* layout */
body>main {
  width: 100vw;
	height: 100vh;
	display: grid;
  grid-auto-flow: column;
  grid-auto-columns: var(--col-w);
	overflow-x: scroll;
  scroll-snap-type: x proximity;
}

body>main>* {
	overflow-y: scroll;
  padding: var(--v-un) var(--h-un);
  scroll-snap-align: center;
}

article:focus {
  outline: none;
}

body>main>article#start>h1>a::before {
  content: "> ";
}

body>main>article#start>h1>a:after {
  content: " <";
}

/* toc */
nav.toc {
  margin-block: var(--v-un);
}

/* footnotes */
aside.footnotes {
  margin-block: var(--v-un);
}

aside.footnotes>hr {
  font-weight: bold;
}

/* fenced divs */

div.horizontal {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: 100%;
  gap: calc(2 * var(--h-un));
  overflow-x: scroll;
  scroll-snap-type: x proximity;
}

div.horizontal>* {
  margin-block: unset;
  scroll-snap-align: center;
}

/* math */

.display.math {
  display: block;
  text-align: center;
}

/* fenced pres */
pre.center {
  text-align: center;
}