/* ============================================================
   DISTILL × TUFTE — Hybrid Research Blog Stylesheet
   
   Distill's clean article chrome + Tufte's margin notes
   Designed for technical writing with math, code, and data.
   ============================================================ */

/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  /* Distill-inspired palette */
  --color-bg:          #fff;
  --color-text:        #303030;
  --color-text-light:  #6e6e6e;
  --color-accent:      #d4a04c;
  --color-accent-dark: #b8862e;
  --color-link:        #0d5ba6;
  --color-link-hover:  #094580;
  --color-border:      #e0dcd4;
  --color-code-bg:     #f7f5f0;
  --color-tag-bg:      #f0ece4;
  --color-tag-text:    #6e6246;
  --color-note-line:   #d4a04c;

  /* Typography scale */
  --font-body:    'Source Serif 4', 'Iowan Old Style', 'Palatino Linotype', Palatino, Georgia, serif;
  --font-heading: 'Source Sans 3', 'Gill Sans', 'Helvetica Neue', Helvetica, sans-serif;
  --font-mono:    'Fira Code', 'Source Code Pro', 'Consolas', monospace;
  --font-note:    var(--font-body);

  --size-base:    18px;
  --size-small:   0.8rem;
  --size-h1:      2.2rem;
  --size-h2:      1.5rem;
  --size-h3:      1.2rem;

  --line-height:  1.72;
  --content-width: 680px;
  --margin-width:  220px;
  --gap:           40px;
}


/* --- Page Layout --- */
html {
  font-size: var(--size-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: var(--line-height);
}

/* Distill-style top accent bar */
body::before {
  content: '';
  display: block;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-dark));
}

/* --- Article Container — content + margin column --- */
.article-wrapper {
  display: grid;
  grid-template-columns: var(--content-width) var(--margin-width);
  gap: var(--gap);
  max-width: calc(var(--content-width) + var(--margin-width) + var(--gap));
  margin: 0 auto;
  padding: 3rem 1.5rem 6rem;
  position: relative;
}

article {
  grid-column: 1;
  min-width: 0;
}


/* --- Site Header --- */
.site-header {
  max-width: calc(var(--content-width) + var(--margin-width) + var(--gap));
  margin: 0 auto;
  padding: 2rem 1.5rem 0;
}

.site-header nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 1rem;
}

.site-header .site-name {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.site-header .site-name:hover {
  color: var(--color-accent-dark);
}

.site-header .nav-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.site-header .nav-links a {
  font-family: var(--font-heading);
  font-size: var(--size-small);
  color: var(--color-text-light);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
}

.site-header .nav-links a:hover {
  color: var(--color-accent-dark);
}


/* --- Article Header (Distill-style) --- */
.article-header {
  margin-bottom: 3rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--color-border);
}

.article-header h1 {
  font-family: var(--font-heading);
  font-size: var(--size-h1);
  font-weight: 800;
  line-height: 1.2;
  color: var(--color-text);
  letter-spacing: -0.02em;
  margin-bottom: 0.8rem;
}

.article-meta {
  font-family: var(--font-heading);
  font-size: var(--size-small);
  color: var(--color-text-light);
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1.5rem;
  align-items: center;
}

.article-meta .author {
  font-weight: 600;
}

.article-meta .date::before {
  content: '·';
  margin-right: 0.3rem;
  color: var(--color-border);
}

.article-tags {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.8rem;
}

.article-tags .tag {
  font-family: var(--font-heading);
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  padding: 0.2em 0.7em;
  border-radius: 3px;
  text-decoration: none;
}

.article-tags .tag:hover {
  background: var(--color-accent);
  color: #fff;
}

.article-summary {
  font-style: italic;
  color: var(--color-text-light);
  margin-top: 1rem;
  font-size: 1.02rem;
  line-height: 1.6;
}


/* --- Body Typography --- */
article p {
  margin-bottom: 1.2rem;
}

article h2 {
  font-family: var(--font-heading);
  font-size: var(--size-h2);
  font-weight: 700;
  margin-top: 2.5rem;
  margin-bottom: 0.8rem;
  color: var(--color-text);
  letter-spacing: -0.01em;
}

article h3 {
  font-family: var(--font-heading);
  font-size: var(--size-h3);
  font-weight: 600;
  margin-top: 2rem;
  margin-bottom: 0.6rem;
}

article a {
  color: var(--color-link);
  text-decoration: underline;
  text-decoration-color: rgba(13, 91, 166, 0.3);
  text-underline-offset: 2px;
  transition: text-decoration-color 0.2s;
}

article a:hover {
  text-decoration-color: var(--color-link-hover);
}

article ul, article ol {
  margin-bottom: 1.2rem;
  padding-left: 1.5rem;
}

article li {
  margin-bottom: 0.4rem;
}

article strong {
  font-weight: 700;
}

article blockquote {
  border-left: 3px solid var(--color-accent);
  margin: 1.5rem 0;
  padding: 0.5rem 0 0.5rem 1.5rem;
  color: var(--color-text-light);
  font-style: italic;
}

article hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 2.5rem 0;
}


/* --- Tufte-Style Margin Notes --- */
.margin-note {
  float: right;
  clear: right;
  width: var(--margin-width);
  margin-right: calc(-1 * (var(--margin-width) + var(--gap)));
  margin-bottom: 1rem;
  font-size: 0.78rem;
  font-family: var(--font-note);
  color: var(--color-text-light);
  line-height: 1.5;
  position: relative;
  padding-left: 14px;
}

.margin-note::before {
  content: '';
  position: absolute;
  left: 0;
  top: 3px;
  width: 3px;
  height: calc(100% - 6px);
  background: var(--color-note-line);
  border-radius: 2px;
}

/* Numbered sidenotes (auto-incrementing) */
article {
  counter-reset: sidenote-counter;
}

.sidenote {
  float: right;
  clear: right;
  width: var(--margin-width);
  margin-right: calc(-1 * (var(--margin-width) + var(--gap)));
  margin-bottom: 1rem;
  font-size: 0.78rem;
  font-family: var(--font-note);
  color: var(--color-text-light);
  line-height: 1.5;
  counter-increment: sidenote-counter;
  padding-left: 14px;
  position: relative;
}

.sidenote::before {
  content: counter(sidenote-counter);
  position: absolute;
  left: 0;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 0.7rem;
  color: var(--color-accent-dark);
}

/* In-text sidenote reference number */
.sidenote-ref {
  counter-increment: sidenote-counter;
}
.sidenote-ref::after {
  content: counter(sidenote-counter);
  font-size: 0.65em;
  vertical-align: super;
  font-family: var(--font-heading);
  font-weight: 700;
  color: var(--color-accent-dark);
  margin-left: 2px;
}


/* --- Code Blocks --- */
article code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--color-code-bg);
  padding: 0.15em 0.4em;
  border-radius: 3px;
}

article pre {
  background: var(--color-code-bg);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 1.2rem 1.5rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
  line-height: 1.5;
}

article pre code {
  background: none;
  padding: 0;
  font-size: 0.82rem;
}


/* --- Math (KaTeX) --- */
.katex-display {
  margin: 1.5rem 0;
  overflow-x: auto;
  padding: 0.5rem 0;
}


/* --- Figures --- */
article figure {
  margin: 2rem 0;
}

article figure img {
  max-width: 100%;
  height: auto;
}

article figcaption {
  font-family: var(--font-heading);
  font-size: var(--size-small);
  color: var(--color-text-light);
  margin-top: 0.6rem;
  line-height: 1.5;
}

/* Full-width figure (breaks out of content column) */
figure.full-width {
  width: calc(var(--content-width) + var(--margin-width) + var(--gap));
  max-width: none;
}


/* --- Blog Index (article listing) --- */
.blog-index {
  list-style: none;
  padding: 0;
}

.blog-index li {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--color-border);
}

.blog-index li:first-child {
  padding-top: 0;
}

.blog-index .post-title {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  font-weight: 700;
  display: block;
  margin-bottom: 0.3rem;
}

.blog-index .post-title a {
  color: var(--color-text);
  text-decoration: none;
}

.blog-index .post-title a:hover {
  color: var(--color-link);
}

.blog-index .post-meta {
  font-family: var(--font-heading);
  font-size: var(--size-small);
  color: var(--color-text-light);
  margin-bottom: 0.4rem;
}

.blog-index .post-summary {
  font-size: 0.95rem;
  color: var(--color-text-light);
  line-height: 1.6;
}


/* --- Page Footer --- */
.site-footer {
  max-width: calc(var(--content-width) + var(--margin-width) + var(--gap));
  margin: 0 auto;
  padding: 2rem 1.5rem;
  border-top: 1px solid var(--color-border);
  font-family: var(--font-heading);
  font-size: var(--size-small);
  color: var(--color-text-light);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-footer a {
  color: var(--color-text-light);
  text-decoration: none;
}

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


/* ============================================================
   RESPONSIVE — collapse margin notes below content
   ============================================================ */
@media (max-width: 1020px) {
  .article-wrapper {
    grid-template-columns: 1fr;
    max-width: var(--content-width);
  }

  .margin-note,
  .sidenote {
    float: none;
    width: 100%;
    margin-right: 0;
    margin-top: 0.5rem;
    margin-bottom: 1rem;
    padding: 0.8rem 1rem;
    background: var(--color-code-bg);
    border-left: 3px solid var(--color-note-line);
    border-radius: 0 4px 4px 0;
    font-size: 0.85rem;
  }

  .margin-note::before {
    display: none;
  }

  figure.full-width {
    width: 100%;
  }
}

@media (max-width: 720px) {
  :root {
    --size-base: 16px;
    --size-h1: 1.7rem;
    --size-h2: 1.3rem;
  }

  .site-header nav {
    flex-direction: column;
    gap: 0.8rem;
  }

  .article-wrapper {
    padding: 2rem 1rem 4rem;
  }

  .site-footer {
    flex-direction: column;
    gap: 0.5rem;
    text-align: center;
  }
}