/* ------------------------------------------------------------------
   Foundry — theme follows the OS (prefers-color-scheme). No toggle, no JS.
   ------------------------------------------------------------------ */

:root {
  color-scheme: light dark;

  --bg: #fdfdfc;
  --bg-raised: #f4f3f0;
  --fg: #1b1b1f;
  --fg-muted: #5f6368;
  --fg-faint: #8a8d93;
  --border: #e3e1dc;
  --accent: #b4532a;
  --accent-soft: #f6e6dd;
  --link: #9a4321;
  --code-bg: #f4f3f0;
  --code-fg: #24292e;
  --selection: #f3d9c9;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.05);

  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Inter, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "JetBrains Mono", "Cascadia Code", "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --measure: 44rem;
  --gutter: clamp(1rem, 4vw, 2rem);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121214;
    --bg-raised: #1b1b1f;
    --fg: #e6e4df;
    --fg-muted: #9a9890;
    --fg-faint: #6f6e69;
    --border: #2a2a2e;
    --accent: #e8875a;
    --accent-soft: #2e2019;
    --link: #f09a6e;
    --code-bg: #1b1b1f;
    --code-fg: #e1e4e8;
    --selection: #4a2c1c;
    --shadow: none;
  }
}

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

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

html {
  font-family: var(--font-sans);
  font-size: 106.25%; /* 17px */
  line-height: 1.65;
  -webkit-text-size-adjust: 100%;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  /* Always reserve space for the vertical scrollbar. Without this, short pages
     (no scrollbar) and long pages (scrollbar) have different viewport widths,
     so the centred column jumps sideways when navigating between them. */
  scrollbar-gutter: stable;
}

@supports not (scrollbar-gutter: stable) {
  html {
    overflow-y: scroll;
  }
}

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
}

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

a {
  color: var(--link);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.15em;
  text-decoration-color: color-mix(in srgb, var(--link) 45%, transparent);
}

a:hover {
  text-decoration-color: currentColor;
}

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

.skip-link {
  position: absolute;
  left: -999px;
  top: 0.5rem;
  background: var(--bg-raised);
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
}

.skip-link:focus {
  left: 0.5rem;
  z-index: 10;
}

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

.site-header,
.site-footer,
main {
  width: min(100% - 2 * var(--gutter), var(--measure));
  margin-inline: auto;
}

.site-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 1.5rem 2.5rem;
}

.site-name {
  font-weight: 650;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
  color: var(--fg);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.site-mark {
  width: 0.7rem;
  height: 0.7rem;
  border-radius: 2px;
  background: var(--accent);
  transform: rotate(45deg);
  display: inline-block;
}

.site-nav {
  display: flex;
  gap: 1.1rem;
  font-size: 0.95rem;
}

.site-nav a {
  color: var(--fg-muted);
  text-decoration: none;
}

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

main {
  flex: 1;
}

.site-footer {
  padding-block: 3rem 2rem;
  color: var(--fg-muted);
  font-size: 0.875rem;
  border-top: 1px solid var(--border);
  margin-top: 3rem;
}

.site-footer a {
  color: inherit;
}

/* ---- index ----------------------------------------------------------- */

.intro {
  margin-bottom: 2.5rem;
}

.intro h1 {
  font-size: clamp(1.6rem, 4vw, 2.1rem);
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 0.6rem;
}

.intro p {
  color: var(--fg-muted);
  margin: 0;
  max-width: 38rem;
}

.year-group {
  display: grid;
  grid-template-columns: 5rem 1fr;
  gap: 0 1.5rem;
  margin-bottom: 2rem;
}

.year {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--fg-faint);
  margin: 0.3rem 0 0;
  font-variant-numeric: tabular-nums;
}

.post-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.post-item {
  padding-block: 0.25rem 1.5rem;
}

.post-item-title {
  font-size: 1.2rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--fg);
  text-decoration: none;
}

.post-item-title:hover {
  color: var(--link);
}

.post-item-summary {
  margin: 0.3rem 0 0.45rem;
  color: var(--fg-muted);
}

.post-item-meta {
  margin: 0;
  font-size: 0.85rem;
  color: var(--fg-faint);
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.9rem;
  align-items: center;
}

@media (max-width: 40rem) {
  .year-group {
    grid-template-columns: 1fr;
  }
  .year {
    margin-bottom: 0.5rem;
  }
}

.empty {
  color: var(--fg-muted);
}

/* ---- tags & badges --------------------------------------------------- */

.tags {
  display: inline-flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.tag {
  font-size: 0.78rem;
  line-height: 1;
  padding: 0.3rem 0.55rem;
  border-radius: 999px;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  color: var(--fg-muted);
  text-decoration: none;
  white-space: nowrap;
}

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

.tag-large {
  font-size: 0.95rem;
  padding: 0.45rem 0.8rem;
}

.tag-cloud {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.tag-cloud li {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.tag-count {
  font-size: 0.8rem;
  color: var(--fg-faint);
  font-variant-numeric: tabular-nums;
}

.badge {
  display: inline-block;
  vertical-align: middle;
  margin-left: 0.5rem;
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.2rem 0.45rem;
  border-radius: 4px;
  background: var(--accent-soft);
  color: var(--accent);
}

/* ---- post ------------------------------------------------------------- */

.post-header {
  margin-bottom: 2rem;
}

.post-header h1 {
  font-size: clamp(1.75rem, 5vw, 2.4rem);
  line-height: 1.15;
  letter-spacing: -0.025em;
  margin: 0 0 0.75rem;
}

.post-meta {
  margin: 0 0 0.75rem;
  font-size: 0.9rem;
  color: var(--fg-muted);
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
}

.meta-sep {
  color: var(--fg-faint);
}

.post-summary {
  font-size: 1.1rem;
  color: var(--fg-muted);
  margin: 0 0 1rem;
}

.post-footer {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  font-size: 0.95rem;
}

/* ---- table of contents ----------------------------------------------- */

.toc {
  margin: 0 0 2rem;
  padding: 0.75rem 1rem;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.92rem;
}

.toc summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--fg-muted);
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.toc ol {
  list-style: none;
  margin: 0.6rem 0 0;
  padding: 0;
}

.toc li {
  margin: 0.25rem 0;
}

.toc .toc-l3 {
  padding-left: 1.1rem;
  font-size: 0.88rem;
}

.toc a {
  color: var(--fg);
  text-decoration: none;
}

.toc a:hover {
  color: var(--link);
}

/* ---- prose ------------------------------------------------------------- */

.prose > * + * {
  margin-block-start: 1.1em;
}

.prose h2,
.prose h3,
.prose h4 {
  line-height: 1.25;
  letter-spacing: -0.015em;
  margin-block-start: 2.2em;
  margin-block-end: 0.6em;
  scroll-margin-top: 1.5rem;
}

.prose h2 {
  font-size: 1.5rem;
}

.prose h3 {
  font-size: 1.2rem;
}

.prose h4 {
  font-size: 1.02rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--fg-muted);
}

.heading-anchor {
  margin-left: 0.35em;
  color: var(--fg-faint);
  text-decoration: none;
  opacity: 0;
  transition: opacity 120ms;
}

.prose h2:hover .heading-anchor,
.prose h3:hover .heading-anchor,
.prose h4:hover .heading-anchor,
.heading-anchor:focus {
  opacity: 1;
}

.prose p {
  margin-block: 0;
}

.prose p + p {
  margin-block-start: 1.1em;
}

.prose ul,
.prose ol {
  padding-left: 1.5rem;
}

.prose li + li {
  margin-top: 0.3em;
}

.prose hr {
  border: 0;
  height: 1px;
  background: var(--border);
  margin-block: 2.5rem;
}

.prose blockquote {
  margin-inline: 0;
  padding: 0.25rem 0 0.25rem 1.1rem;
  border-left: 3px solid var(--accent);
  color: var(--fg-muted);
}

.prose blockquote p {
  margin: 0;
}

.prose strong {
  font-weight: 650;
}

.prose img,
.prose video {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
}

.prose figure {
  margin-inline: 0;
  text-align: center;
}

.prose figcaption {
  margin-top: 0.6rem;
  font-size: 0.875rem;
  color: var(--fg-muted);
  text-align: center;
}

.prose table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  display: block;
  overflow-x: auto;
}

.prose th,
.prose td {
  text-align: left;
  padding: 0.5rem 0.75rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

.prose th {
  font-weight: 600;
  color: var(--fg-muted);
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.prose kbd {
  font-family: var(--font-mono);
  font-size: 0.85em;
  padding: 0.1em 0.4em;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 4px;
  background: var(--bg-raised);
}

/* ---- inline & block code ------------------------------------------------ */

code,
pre,
kbd,
samp {
  font-family: var(--font-mono);
  font-feature-settings: "liga" 0;
}

.prose :not(pre) > code {
  font-size: 0.86em;
  padding: 0.12em 0.35em;
  border-radius: 4px;
  background: var(--code-bg);
  border: 1px solid var(--border);
  overflow-wrap: anywhere;
}

.codeblock {
  position: relative;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--code-bg);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.codeblock-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--fg-muted);
  padding: 0.45rem 1rem;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--code-bg) 70%, var(--bg));
}

.codeblock[data-lang]::after {
  content: attr(data-lang);
  position: absolute;
  top: 0.45rem;
  right: 0.7rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--fg-faint);
  pointer-events: none;
}

.codeblock-label + pre {
  padding-top: 0.9rem;
}

.codeblock pre {
  margin: 0;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  font-size: 0.86rem;
  line-height: 1.6;
  tab-size: 2;
  background: transparent !important; /* shiki sets an inline background; the theme owns it */
}

.codeblock pre code {
  display: block;
  min-width: max-content;
}

/* shiki dual themes: colours are emitted as CSS variables on each span. */
.shiki,
.shiki span {
  color: var(--shiki-light, var(--code-fg));
  font-style: var(--shiki-light-font-style, inherit);
  font-weight: var(--shiki-light-font-weight, inherit);
  text-decoration: var(--shiki-light-text-decoration, inherit);
}

@media (prefers-color-scheme: dark) {
  .shiki,
  .shiki span {
    color: var(--shiki-dark, var(--code-fg));
    font-style: var(--shiki-dark-font-style, inherit);
    font-weight: var(--shiki-dark-font-weight, inherit);
    text-decoration: var(--shiki-dark-text-decoration, inherit);
  }
}

/* Plain-text fences (no language) */
.codeblock pre:not(.shiki) {
  color: var(--code-fg);
}

/* ---- maths -------------------------------------------------------------- */

.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding-block: 0.25rem;
}

.katex {
  font-size: 1.05em;
}

/* ---- footnotes ------------------------------------------------------------ */

.footnotes {
  margin-top: 3rem;
  font-size: 0.9rem;
  color: var(--fg-muted);
}

.footnotes-sep {
  margin-block: 2rem 1rem;
}

.footnotes ol {
  padding-left: 1.25rem;
}

.footnote-ref a,
.footnote-backref {
  text-decoration: none;
}

.footnote-ref a {
  padding: 0 0.15em;
}

/* ---- embedded demos -------------------------------------------------------- */

.demo {
  display: block;
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-raised);
  color-scheme: light dark;
}

/* ---- print ----------------------------------------------------------------- */

@media print {
  .site-nav,
  .site-footer,
  .toc,
  .post-footer,
  .heading-anchor {
    display: none;
  }
  .codeblock pre {
    white-space: pre-wrap;
  }
}