/* causalab-mini docs — one stylesheet, no framework.
 *
 * Every colour is a token on :root. Dark mode is the same tokens redefined,
 * once under prefers-color-scheme (guarded so a manual "light" wins) and once
 * under an explicit [data-theme="dark"]. Nothing else in the file names a
 * literal colour, so a page never has to care which theme it is in.
 */

:root {
  --bg:           #fbfaf8;
  --bg-raised:    #ffffff;
  --bg-sunken:    #f2f0ec;
  --fg:           #1d1f21;
  --fg-muted:     #5d6368;
  --fg-faint:     #868d93;
  --rule:         #e2ded7;
  --rule-strong:  #cec9c0;
  --accent:       #0f6f6c;
  --accent-bg:    #e4f1f0;
  --accent-fg:    #0b5250;
  --accent-strong:#0b5250;
  --code-bg:      #f4f2ee;
  --code-fg:      #24292f;
  --warn-bg:      #fdf6e3;
  --warn-rule:    #d8c48a;

  --font-body: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI",
               Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
               "Liberation Mono", monospace;

  --measure: 34rem;     /* the line-length limit for running prose */
  --sidebar: 16rem;
  --gutter: 1rem;

  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg:           #16181a;
    --bg-raised:    #1d2023;
    --bg-sunken:    #121415;
    --fg:           #e6e3de;
    --fg-muted:     #a5aab0;
    --fg-faint:     #7e858c;
    --rule:         #2e3236;
    --rule-strong:  #434950;
    --accent:       #5fc9c4;
    --accent-bg:    #16312f;
    --accent-fg:    #8fdedb;
    --accent-strong:#8fdedb;
    --code-bg:      #1b1e21;
    --code-fg:      #dcd9d4;
    --warn-bg:      #2a2418;
    --warn-rule:    #6b5a2e;
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg:           #16181a;
  --bg-raised:    #1d2023;
  --bg-sunken:    #121415;
  --fg:           #e6e3de;
  --fg-muted:     #a5aab0;
  --fg-faint:     #7e858c;
  --rule:         #2e3236;
  --rule-strong:  #434950;
  --accent:       #5fc9c4;
  --accent-bg:    #16312f;
  --accent-fg:    #8fdedb;
  --accent-strong:#8fdedb;
  --code-bg:      #1b1e21;
  --code-fg:      #dcd9d4;
  --warn-bg:      #2a2418;
  --warn-rule:    #6b5a2e;
  color-scheme: dark;
}

/* ------------------------------------------------------------------ base */

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

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  overflow-wrap: break-word;
}

a { color: var(--accent-strong); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }

h1, h2, h3, h4 { line-height: 1.25; font-weight: 600; margin: 0 0 .5em; }
h1 { font-size: 1.9rem; letter-spacing: -.01em; margin-bottom: .3em; }
h2 { font-size: 1.3rem; margin-top: 2.4em; padding-top: .6em; border-top: 1px solid var(--rule); }
h3 { font-size: 1.05rem; margin-top: 1.9em; color: var(--fg); }
h4 { font-size: .95rem; margin-top: 1.5em; color: var(--fg-muted); }

/* a heading is a link target; the affordance appears when you point at it,
   and stays visible while it has focus so a keyboard can reach it */
.anchor {
  margin-left: .35em;
  font-weight: 400;
  font-size: .8em;
  color: var(--fg-faint);
  text-decoration: none;
  opacity: 0;
}
h2:hover > .anchor, h3:hover > .anchor, .anchor:focus { opacity: 1; }
.anchor:hover { color: var(--accent-strong); }
:target { scroll-margin-top: 1rem; }

sup, sub { line-height: 0; font-size: .75em; }

p, ul, ol, dl { margin: 0 0 1em; }
li { margin-bottom: .3em; }
li > ul, li > ol { margin-top: .3em; }

hr { border: 0; border-top: 1px solid var(--rule); margin: 2.5em 0; }

/* ---------------------------------------------------------------- layout */

.layout {
  display: grid;
  grid-template-columns: var(--sidebar) minmax(0, 1fr);
  min-height: 100vh;
}

/* the bar that only exists at phone width */
.topbar {
  display: none;
  position: sticky;
  top: 0;
  z-index: 20;
  align-items: center;
  gap: .75rem;
  padding: .5rem var(--gutter);
  background: var(--bg-raised);
  border-bottom: 1px solid var(--rule);
}

.topbar .brand { font-weight: 600; font-size: .95rem; }

.iconbutton {
  font: inherit;
  font-size: .85rem;
  line-height: 1;
  padding: .45rem .6rem;
  color: var(--fg-muted);
  background: var(--bg-sunken);
  border: 1px solid var(--rule-strong);
  border-radius: 5px;
  cursor: pointer;
}
.iconbutton:hover { color: var(--fg); border-color: var(--accent); }

/* ------------------------------------------------------------------- nav */

.sidebar {
  grid-column: 1;
  border-right: 1px solid var(--rule);
  background: var(--bg-sunken);
  padding: 1.6rem 1rem 3rem;
  position: sticky;
  top: 0;
  align-self: start;
  max-height: 100vh;
  overflow-y: auto;
}

.sidebar .brand {
  display: block;
  font-weight: 600;
  font-size: 1rem;
  color: var(--fg);
  text-decoration: none;
  margin-bottom: .15rem;
}
.sidebar .brand-sub {
  display: block;
  font-size: .78rem;
  color: var(--fg-faint);
  margin-bottom: 1.4rem;
}

.sidebar nav ol { list-style: none; margin: 0 0 1.4rem; padding: 0; }
.sidebar nav > ol > li { margin-bottom: .1rem; }

.sidebar nav h2 {
  font-size: .72rem;
  font-weight: 600;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--fg-faint);
  border: 0;
  margin: 1.5rem 0 .5rem;
  padding: 0;
}

.sidebar nav a {
  display: block;
  padding: .24rem .5rem;
  border-radius: 4px;
  font-size: .88rem;
  color: var(--fg-muted);
  text-decoration: none;
  border-left: 2px solid transparent;
}
.sidebar nav a:hover { color: var(--fg); background: var(--bg-raised); }

.sidebar nav a[aria-current="page"] {
  color: var(--accent-strong);
  background: var(--accent-bg);
  border-left-color: var(--accent);
  font-weight: 600;
}

.sidebar nav .sub { margin-left: .55rem; padding-left: .55rem; border-left: 1px solid var(--rule); }
.sidebar nav .sub a { font-size: .84rem; }

.sidebar .footer {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--rule);
  font-size: .78rem;
  color: var(--fg-faint);
}
.sidebar .footer a { color: var(--fg-muted); }

/* --------------------------------------------------------------- content */

main {
  grid-column: 2;
  padding: 2.6rem 2.5rem 6rem;
  min-width: 0;
}

.page { max-width: 52rem; }

/* running prose gets the tighter measure; tables and code may use the width */
.page > p,
.page > ul,
.page > ol,
.page > dl,
.page > blockquote { max-width: var(--measure); }

/* …but a card grid is a layout, not prose, and takes the full column */
.page > ul.cards { max-width: 52rem; }

.lede { font-size: 1.08rem; color: var(--fg-muted); }

.page > header { margin-bottom: 2rem; }

.eyebrow {
  font-size: .75rem;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--fg-faint);
  margin: 0 0 .35rem;
}

/* ------------------------------------------------------------------ code */

code, kbd, samp {
  font-family: var(--font-mono);
  font-size: .875em;
}

:not(pre) > code {
  background: var(--code-bg);
  color: var(--code-fg);
  padding: .1em .35em;
  border-radius: 3px;
  border: 1px solid var(--rule);
}

pre {
  background: var(--code-bg);
  color: var(--code-fg);
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: .85rem 1rem;
  overflow-x: auto;
  font-size: .82rem;
  line-height: 1.5;
  margin: 0 0 1.2em;
  tab-size: 2;
}

/* A box that scrolls sideways gets a scrollbar from the browser, and a
   default one is drawn light whatever the page is. Name its colours. */
pre, table, figure, .sidebar { scrollbar-width: thin; scrollbar-color: var(--rule-strong) transparent; }
pre code { font-size: inherit; background: none; border: 0; padding: 0; }

/* a block with its source stated above it */
.listing { margin: 0 0 1.4em; }
.listing > figcaption {
  font-family: var(--font-mono);
  font-size: .76rem;
  color: var(--fg-faint);
  padding: .2rem 0 .35rem;
}
.listing > figcaption .what { font-family: var(--font-body); font-style: italic; }
.listing pre { margin-bottom: 0; }

/* a long listing the reader may fold away */
details.listing > summary {
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: .76rem;
  color: var(--fg-muted);
  padding: .3rem 0;
}
details.listing > summary:hover { color: var(--accent-strong); }

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

table {
  border-collapse: collapse;
  width: 100%;
  font-size: .88rem;
  margin: 0 0 1.4em;
  display: block;
  overflow-x: auto;
}
thead th {
  text-align: left;
  font-weight: 600;
  font-size: .78rem;
  letter-spacing: .03em;
  text-transform: uppercase;
  color: var(--fg-faint);
  border-bottom: 1px solid var(--rule-strong);
  padding: .4rem .7rem .4rem 0;
  white-space: nowrap;
}
tbody td {
  vertical-align: top;
  padding: .45rem .7rem .45rem 0;
  border-bottom: 1px solid var(--rule);
}
tbody tr:last-child td { border-bottom: 0; }
td code, th code { white-space: nowrap; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; padding-right: 1.2rem; }

/* ----------------------------------------------------------------- notes */

.note, .caution {
  border-left: 3px solid var(--accent);
  background: var(--accent-bg);
  padding: .7rem 1rem;
  border-radius: 0 5px 5px 0;
  margin: 0 0 1.4em;
  font-size: .92rem;
  max-width: var(--measure);
}
.note > :last-child, .caution > :last-child { margin-bottom: 0; }
.note .label, .caution .label {
  display: block;
  font-size: .72rem;
  letter-spacing: .07em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin-bottom: .2rem;
}
.caution { border-left-color: var(--warn-rule); background: var(--warn-bg); }

/* a page that has not been written yet */
.stub {
  border: 1px dashed var(--rule-strong);
  background: var(--bg-sunken);
  border-radius: 6px;
  padding: 1.2rem 1.4rem;
  max-width: var(--measure);
}
.stub .label {
  display: inline-block;
  font-size: .72rem;
  letter-spacing: .07em;
  text-transform: uppercase;
  color: var(--fg-faint);
  border: 1px solid var(--rule-strong);
  border-radius: 99px;
  padding: .05rem .55rem;
  margin-bottom: .6rem;
}
.stub > :last-child { margin-bottom: 0; }

/* ----------------------------------------------------------------- cards */

.cards {
  list-style: none;
  padding: 0;
  margin: 0 0 1.6em;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(15rem, 1fr));
  gap: .75rem;
  max-width: 52rem;
}
.cards li { margin: 0; }
.cards a {
  display: block;
  height: 100%;
  padding: .7rem .9rem;
  background: var(--bg-raised);
  border: 1px solid var(--rule);
  border-radius: 6px;
  text-decoration: none;
  color: var(--fg);
}
.cards a:hover { border-color: var(--accent); }
.cards .title { font-weight: 600; font-size: .92rem; display: block; margin-bottom: .15rem; }
.cards .blurb { font-size: .82rem; color: var(--fg-muted); display: block; line-height: 1.45; }
.cards a[data-status="stub"] .title::after {
  content: "in progress";
  font-weight: 400;
  font-size: .68rem;
  letter-spacing: .05em;
  text-transform: uppercase;
  color: var(--fg-faint);
  border: 1px solid var(--rule-strong);
  border-radius: 99px;
  padding: 0 .4rem;
  margin-left: .4rem;
  vertical-align: .08em;
}

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

figure { margin: 0 0 1.5em; }
figure svg { max-width: 100%; height: auto; display: block; }
figure > figcaption {
  font-size: .82rem;
  color: var(--fg-muted);
  padding-top: .5rem;
  max-width: var(--measure);
}

/* a bar chart drawn with divs: one row per label */
.bars { margin: 0 0 1.5em; max-width: 38rem; }
.bars .row {
  display: grid;
  /* the label and the number are monospace and never break; the bar takes
     whatever is left, at any width */
  grid-template-columns: max-content 1fr max-content;
  align-items: center;
  gap: .5rem;
  font-size: .8rem;
  font-variant-numeric: tabular-nums;
  padding: .08rem 0;
}
.bars .key { color: var(--fg-muted); text-align: right; font-family: var(--font-mono); }
.bars .key, .bars .val { white-space: nowrap; }
.bars .track { background: var(--bg-sunken); border: 1px solid var(--rule); border-radius: 2px; height: .8rem; }
.bars .fill { background: var(--accent); height: 100%; border-radius: 1px; }
.bars .val { color: var(--fg-muted); font-family: var(--font-mono); }
.bars .head { font-size: .72rem; letter-spacing: .05em; text-transform: uppercase; color: var(--fg-faint); }

/* ------------------------------------------------------------- see also */

.seealso {
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--rule);
  font-size: .9rem;
  max-width: var(--measure);
}
.seealso h2 {
  border: 0;
  margin: 0 0 .4rem;
  padding: 0;
  font-size: .72rem;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--fg-faint);
}
.seealso h2 > .anchor { font-size: 1em; letter-spacing: 0; }
.seealso ul { margin: 0; padding-left: 1.1rem; }

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

@media (max-width: 62rem) {
  .layout { display: block; }

  .topbar { display: flex; }

  .sidebar {
    display: none;
    position: static;
    max-height: none;
    border-right: 0;
    border-bottom: 1px solid var(--rule);
    padding: 1rem var(--gutter) 1.5rem;
  }
  body[data-nav="open"] .sidebar { display: block; }
  .sidebar .brand, .sidebar .brand-sub { display: none; }

  main { padding: 1.5rem var(--gutter) 4rem; }
  h1 { font-size: 1.5rem; }
  h2 { font-size: 1.15rem; }
  .anchor { opacity: .5; }

  /* A diagram does not reflow. Shrunk to a phone's column a 640-wide one
     puts its labels under 6px, so below this width the figure scrolls
     instead — the same thing a wide table does. 490px keeps the smallest
     label above 8px. */
  figure { overflow-x: auto; }
  figure > svg { min-width: 490px; }
  :target { scroll-margin-top: 4rem; }   /* clear the sticky topbar */
  .bars .row { gap: .35rem; font-size: .72rem; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}

/* the toggle is useless without scripting, so it hides itself until JS runs */
.js-only { display: none; }
body[data-js="on"] .js-only { display: inline-block; }

/* ---------------------------------------------------------- keyboard use */

.skip { position: absolute; left: -9999px; }
.skip:focus {
  position: fixed;
  left: .5rem;
  top: .5rem;
  z-index: 50;
  background: var(--bg-raised);
  color: var(--fg);
  border: 1px solid var(--accent);
  border-radius: 5px;
  padding: .5rem .8rem;
  text-decoration: none;
}

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