:root {
  /* ---- Layout ------------------------------------------------------- */
  --content-width: 44rem;   /* width of the centered text column */
  --gutter: 1.5rem;         /* minimum breathing room on small screens */

  /* ---- Fonts --------------------------------------------------------- */
  --font-heading: 'IBM Plex Sans Condensed', 'Source Sans 3', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-body: 'Source Serif 4', Georgia, serif;
  --font-mono: 'IBM Plex Mono', SFMono-Regular, Menlo, Consolas, ui-monospace, monospace;

  /* ---- Type scale ----------------------------------------------------- */
  --font-size-base: 18px;
  --font-body-weight: 400;
  --line-height-base: 1.7;
  --title-size: clamp(2.8rem, 8vw, 3.5rem);
  --h1-size: 1.5rem;
  --h2-size: 1.4rem;
  --h3-size: 1.2rem;
  --small-size: 0.85rem;

  /* ---- Color ----------------------------------------------------------- */
--color-bg: #fcfcfb;
--color-text: #262425;
--color-text-muted: #78737a;
--color-border: #e5e2e6;
/* --color-accent: #7d4b56; */
/* --color-accent: #8f3550; */
--color-accent: #9c3a48;
--color-code-bg: #f2f0f1;

  /* ---- Spacing rhythm --------------------------------------------------- */
  --space-xs: 0.4rem;
  --space-sm: 0.8rem;
  --space-md: 1.6rem;
  --space-lg: 3rem;
  --space-xl: 5rem;
}

/* ---- Local fonts -------------------------------------------- */

/* - - - Source Serif 4 - - - */
@font-face {
  font-family: "Source Serif 4";
  font-style: normal;
  font-weight: 400;
  src: url("../static/fonts/SourceSerif4-Regular.otf.woff2") format("woff2");
  font-display: swap;
}

@font-face {
  font-family: "Source Serif 4";
  font-style: italic;
  font-weight: 400;
  src: url("../static/fonts/SourceSerif4-It.otf.woff2") format("woff2");
  font-display: swap;
}

/* - - - Plex Sans Condensed - - - */
@font-face {
  font-family: "IBM Plex Sans Condensed";
  font-style: normal;
  font-weight: 700;
  src: url("../static/fonts/IBMPlexSansCondensed-Bold.woff2") format("woff2");
  font-display: swap;
}

@font-face {
  font-family: "IBM Plex Sans Condensed";
  font-style: italic;
  font-weight: 700;
  src: url("../static/fonts/IBMPlexSansCondensed-BoldItalic.woff2") format("woff2");
  font-display: swap;
}

/* - - - Plex Mono - - - */
@font-face {
  font-family: "IBM Plex Mono";
  font-style: normal;
  font-weight: 450;
  src: url("../static/fonts/IBMPlexMono-Text.woff2") format("woff2");
  font-display: swap;
}

@font-face {
  font-family: "IBM Plex Mono";
  font-style: italic;
  font-weight: 450;
  src: url("../static/fonts/IBMPlexMono-TextItalic.woff2") format("woff2");
  font-display: swap;
}

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

/* ---- Base -------------------------------------------------------------- */
html {
  font-size: var(--font-size-base);
}

body {
  margin: 0 auto;
  max-width: var(--content-width);
  padding: var(--space-xl) var(--gutter) var(--space-lg);
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  font-weight: var(--font-body-weight);
  font-optical-sizing: auto; /* lets the variable font pick the right opsz per size */
  line-height: var(--line-height-base);
  color: var(--color-text);
  background: var(--color-bg);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

::selection {
  background: color-mix(in srgb, var(--color-accent) 25%, transparent);
}

/* ---- Header / site title / nav ----------------------------------------
   Rendered by org-html-preamble-format in publish.el, above #content. */
.site-header {
  text-align: center;
  margin-bottom: var(--space-xl);
}

.site-title {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--title-size);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  line-height: 1.1;
}

.site-title a {
  color: var(--color-text);
  border-bottom: none;
}

.site-title a:hover {
  color: var(--color-accent);
}

.site-nav {
  margin-top: var(--space-sm);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-md);
}

.site-nav a {
  font-family: var(--font-mono);
  font-size: var(--small-size);
  font-weight: 450;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  border-bottom: 1px solid transparent;
}

.site-nav a:hover,
.site-nav a:focus {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* ---- Page content ------------------------------------------------------- */
#content {
  padding-bottom: var(--space-lg);
}

#content > h1.title {
  font-family: var(--font-heading);
  font-size: var(--h1-size);
  font-weight: 700;
  text-align: center;
  margin-bottom: var(--space-lg);
}

p {
  margin: 0 0 var(--space-md);
}

/* ---- Links --------------------------------------------------------------- */
a {
  color: var(--color-text);
  text-decoration: none;
  border-bottom: 1px solid var(--color-border);
  transition: color 0.15s ease, border-color 0.15s ease;
}

a:hover,
a:focus {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* ---- Headings ------------------------------------------------------------ */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.3;
  margin: var(--space-lg) 0 var(--space-sm);
}

.outline-1 > h1 {
  font-size: var(--h1-size);
}

.outline-2 > h2 {
  font-size: var(--h2-size);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--color-border);
}

.outline-3 > h3 {
  font-size: var(--h3-size);
  color: var(--color-text-muted);
}

/* ---- Lists ---------------------------------------------------------------- */
ul, ol {
  padding-left: 1.3em;
  margin: 0 0 var(--space-md);
}

li > p {
  margin-bottom: var(--space-xs);
}

/* ---- Blockquote ------------------------------------------------------------ */
blockquote {
  margin: var(--space-md) 0;
  padding: 0 0 0 var(--space-md);
  border-left: 2px solid var(--color-accent);
  color: var(--color-text-muted);
  font-style: italic;
}

/* ---- Rule ------------------------------------------------------------------- */
hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-lg) 0;
}

/* ---- Code / preformatted ------------------------------------------------------ */
code, tt {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--color-code-bg);
  padding: 0.15em 0.35em;
  border-radius: 3px;
}

pre {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.6;
  background: var(--color-code-bg);
  padding: var(--space-sm) var(--space-md);
  border-radius: 4px;
  overflow-x: auto;
}

pre code {
  background: none;
  padding: 0;
}

/* ---- Tables ------------------------------------------------------------------- */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 0 0 var(--space-md);
  font-size: 0.95rem;
}

th, td {
  padding: var(--space-xs) var(--space-sm);
  border-bottom: 1px solid var(--color-border);
  text-align: left;
}

th {
  font-family: var(--font-heading);
  font-weight: 700;
}

/* ---- Images --------------------------------------------------------------------- */
img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: var(--space-md) auto;
}

/* ---- Buttons --------------------------------------------------------------------
   For content markup: #+html: <a class="button button--info button--small" href="...">Label</a> */
.button {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: var(--small-size);
  font-weight: 450;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 0.5em 1em;
  border: 1px solid var(--color-text);
  border-radius: 3px;
  color: var(--color-text);
  background: transparent;
  transition: color 0.15s ease, background-color 0.15s ease, border-color 0.15s ease;
  margin-right: 0.6em;
  margin-bottom: 0.2em;
}

.button:hover,
.button:focus {
  color: var(--color-bg);
  background: var(--color-text);
  border-color: var(--color-text);
}

.button--info,
.button--primary,
.button--success {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.button--info:hover,
.button--primary:hover,
.button--success:hover,
.button--info:focus,
.button--primary:focus,
.button--success:focus {
  color: var(--color-bg);
  background: var(--color-accent);
  border-color: var(--color-accent);
}

.button--secondary {
  border-color: var(--color-border);
  color: var(--color-text-muted);
}

.button--secondary:hover,
.button--secondary:focus {
  color: var(--color-text);
  border-color: var(--color-text);
  background: none;
}

.button--warning,
.button--error {
  border-style: dashed;
}

.button--small {
  font-size: 0.75rem;
  padding: 0.35em 0.8em;
}

.button--large {
  font-size: 0.95rem;
  padding: 0.7em 1.4em;
}

.button--disabled,
a.button[aria-disabled="true"] {
  opacity: 0.45;
  pointer-events: none;
  cursor: not-allowed;
}

/* ---- Collapse -------------------------------------------------------------------
   For content markup:
   #+html: <details class="collapse"><summary class="collapse__summary">Abstract</summary><div class="collapse__content">
   ... normal org paragraphs ...
   #+html: </div></details> */
.collapse {
  margin: var(--space-md) 0;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: var(--space-sm) var(--space-md);
}

.collapse__summary {
  cursor: pointer;
  display: block;
  list-style: none;
  font-family: var(--font-mono);
  font-size: var(--small-size);
  font-weight: 450;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
}

.collapse__summary::-webkit-details-marker {
  display: none;
}

.collapse__summary::before {
  content: "+ ";
  color: var(--color-accent);
}

details[open] > .collapse__summary::before {
  content: "\2212  ";
}

.collapse__summary:hover {
  color: var(--color-accent);
}

.collapse__content {
  margin-top: var(--space-sm);
}

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

/* ---- Table of contents ------------------------------------------------------------ */
#table-of-contents {
  margin: var(--space-lg) 0;
  padding: var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: 4px;
}

#table-of-contents h2 {
  margin-top: 0;
  font-size: var(--small-size);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  border: none;
}

#table-of-contents ul {
  list-style: none;
  padding-left: 0;
  margin-bottom: 0;
}

#table-of-contents li {
  margin: var(--space-xs) 0;
}

#table-of-contents li li {
  padding-left: var(--space-md);
}

/* ---- Footnotes ------------------------------------------------------------------------ */
.footref, .footnum {
  font-family: var(--font-mono);
  color: var(--color-accent);
}

#footnotes {
  margin-top: var(--space-xl);
  padding-top: var(--space-md);
  border-top: 1px solid var(--color-border);
  font-size: var(--small-size);
  color: var(--color-text-muted);
}

/* ---- Postamble (author / date / creator / validation) ---------------------------------- */
#postamble.status {
  margin-top: var(--space-xl);
  padding-top: var(--space-md);
  border-bottom: none;
  text-align: center;
  font-family: var(--font-mono);
  font-size: var(--small-size);
  color: var(--color-text-muted);
}

#postamble.status p {
  margin: 0.2em 0;
}

/* ---- Responsive -------------------------------------------------------------------------- */
@media (max-width: 640px) {
  :root {
    --font-size-base: 16px;
  }

  body {
    padding: var(--space-lg) var(--gutter) var(--space-md);
  }

  .site-header {
    margin-bottom: var(--space-lg);
  }

  .site-nav {
    gap: var(--space-sm) var(--space-md);
  }
}