/* === variables.css === */
/* ET Book web font */
@import url('https://edwardtufte.github.io/et-book/et-book.css');

/* Smooth scrolling for anchor links */
html {
  scroll-behavior: smooth;
}

/* CSS custom properties — light mode */
:root {
  --max-width: 42em;
  --text-color: #444;
  --heading-color: #111;
  --bg-color: #fefefe;
  --link-color: #0645ad;
  --link-visited: #0b0080;
  --link-hover: #06e;
  --code-bg: #f9f8f6;
  --border-color: #ddd;
  --blockquote-color: #666;
  --meta-color: #666;
}

/* Dark mode overrides */
[data-theme="dark"] {
  --text-color: #ddd;
  --heading-color: #eee;
  --bg-color: #1a1a1a;
  --link-color: #69b7ff;
  --link-visited: #b19cd9;
  --link-hover: #89cff0;
  --code-bg: #2a2a2a;
  --border-color: #444;
  --blockquote-color: #aaa;
  --meta-color: #999;
}

/* === base.css === */
/* Base styles: body, typography, links, code, blockquotes, math */

body {
  font-family: 'et-book', 'ETBookOT', 'ET Book', Georgia, 'Times New Roman', serif;
  font-size: 18px;
  line-height: 1.7;
  color: var(--text-color);
  background: var(--bg-color);
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2em;
}

/* Headings */
h1, h2, h3, h4, h5, h6 {
  color: var(--heading-color);
  line-height: 1.25;
  margin-top: 1.4em;
  margin-bottom: 0.5em;
  font-weight: normal;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.2em;
}

h1 { font-size: 1.8em; text-align: left; margin-bottom: 0.5em; }
h2 { font-size: 1.4em; }
h3 { font-size: 1.2em; }
h4 { font-size: 1.1em; font-weight: bold; }
h5 { font-size: 1em;   font-weight: bold; }
h6 { font-size: 0.9em; font-weight: bold; }

/* Paragraphs */
p {
  margin: 1em 0;
  text-align: left;
  hyphens: none;
}

/* Links */
a              { color: var(--link-color);   text-decoration: none; }
a:visited      { color: var(--link-visited); }
a:hover        { color: var(--link-hover);   }

/* Code */
pre {
  background: var(--code-bg);
  padding: 1em;
  overflow-x: auto;
  border: 1px solid var(--border-color);
  border-radius: 2px;
  font-size: 0.9em;
  line-height: 1.4;
}

code {
  font-family: Menlo, Monaco, 'Lucida Console', Consolas, monospace;
  font-size: 0.85em;
  background: var(--code-bg);
  padding: 0.2em 0.4em;
  border-radius: 2px;
}

pre code {
  background: none;
  padding: 0;
  font-size: 1em;
}

/* Blockquotes */
blockquote {
  margin: 1em 0;
  padding-left: 1em;
  border-left: 3px solid var(--border-color);
  color: var(--blockquote-color);
  font-style: italic;
}

/* Horizontal rule */
hr {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 3em 0;
}

/* Text selection */
::selection {
  background: rgba(255, 255, 0, 0.3);
  color: #000;
}

/* Math — scale to match ET Book */
.katex         { font-size: 1.05em; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 1em 0; }

/* Tables */
table {
  margin: 1em 0;
  border-collapse: collapse;
  width: 100%;
  font-size: 0.9em;
}

table th {
  padding: 0.5em;
  background-color: var(--code-bg);
  border: 1px solid var(--border-color);
  font-weight: bold;
}

table td {
  padding: 0.5em;
  border: 1px solid var(--border-color);
}

/* === controls.css === */
/* Fixed UI controls: font switcher, theme toggle, home glyph */

.font-toggle {
  position: fixed;
  top: 0.5em;
  right: 1em;
  background: none;
  border: 1px solid var(--border-color);
  font-size: 0.75em;
  color: var(--text-color);
  cursor: pointer;
  z-index: 100;
  transition: all 0.2s ease;
  padding: 0.4em 0.6em;
  border-radius: 3px;
  white-space: nowrap;
  font-family: inherit;
}

.font-toggle:hover {
  background: var(--code-bg);
  border-color: var(--meta-color);
  color: var(--link-hover);
}

.theme-toggle {
  position: fixed;
  top: 1.8em;
  right: 1.5em;
  background: none;
  border: none;
  font-size: 1.2em;
  color: var(--meta-color);
  cursor: pointer;
  z-index: 100;
  transition: color 0.2s ease;
  line-height: 1;
  padding: 0;
  margin: 0;
}

.theme-toggle:hover { color: var(--link-hover); }

.home-glyph {
  position: fixed;
  top: 1.5em;
  right: 4em;
  font-size: 1.2em;
  color: var(--meta-color);
  text-decoration: none;
  z-index: 100;
  transition: color 0.2s ease;
}

.home-glyph:visited { color: var(--meta-color); }
.home-glyph:hover   { color: var(--link-hover); }

/* === layout.css === */
/* Page layout: header, homepage, post metadata, about section, footer, figures */

/* Homepage header */
header h1 {
  margin-bottom: 0.2em;
  border-bottom: none;
  padding-bottom: 0;
}

.site-subtitle {
  text-align: left;
  font-style: italic;
  color: var(--meta-color);
  margin: 0.5em 0 0 0;
  font-size: 1.1em;
}

.header-separator {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 1.5em 0;
}

.site-description { margin: 0; }

.site-description p {
  margin: 0;
  text-align: left;
  font-style: normal;
  line-height: 1.6;
}

/* Post metadata */
.sequence-nav {
  color: var(--text-color);
  font-size: 0.9em;
  margin-bottom: 1em;
  font-weight: normal;
}

.title-separator {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 1.5em 0 1em 0;
}

.metadata-separator {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 1em 0 2em 0;
}

.metadata {
  color: var(--meta-color);
  font-size: 0.9em;
  text-align: left;
  margin-bottom: 0;
  font-style: italic;
}

/* Date headers on index */
.date-header {
  margin-top: 3em;
  margin-bottom: 1em;
  padding-bottom: 0.5em;
  text-transform: uppercase;
  font-weight: bold;
  font-size: 0.8em;
  color: var(--meta-color);
  border-bottom: 1px solid var(--meta-color);
}

.date-header:first-child { margin-top: 0; }

/* Post list container */
.post-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

/* About section */
.about-section          { margin-top: 2em; }
.about-section h2       { font-size: 1.4em; margin-bottom: 1em; }
.about-section p        { margin-bottom: 1em; }

.about-section ul {
  display: grid;
  grid-template-columns: 1fr 1fr;
  row-gap: 0.3em;
  column-gap: 2em;
  list-style: none;
  padding: 0;
  margin: 0;
}

.about-section ul li { margin: 0; }

/* Sequence header (inside posts) */
.sequence-header   { text-align: center; margin-bottom: 2em; }
.sequence-name     { font-size: 2.5em; font-weight: bold; color: var(--heading-color); margin: 0; line-height: 1.2; }

/* Banner / figures */
.banner-image { margin-top: 1em; margin-bottom: 1em; }

.full-width-figure {
  width: 100%;
  margin-top: 2em;
  margin-bottom: 2em;
  text-align: center;
}

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

.figure-caption {
  font-size: 0.85em;
  color: var(--meta-color);
  margin-top: 0.75em;
  padding: 0 2em;
  line-height: 1.4;
}

/* Footer */
footer {
  margin-top: 4em;
  padding-top: 2em;
  border-top: 1px solid var(--border-color);
  text-align: center;
  font-size: 0.9em;
  color: var(--meta-color);
}

/* === components.css === */
/* Reusable components: post-entry cards, sequence boxes, post links */

/* Post entry cards (standalone posts) */
.post-entry {
  display: block;
  text-decoration: none;
  color: var(--text-color);
  background: var(--code-bg);
  padding: 1.5em;
  margin-bottom: 0.5em;
  border-left: 3px solid transparent;
  transition: all 0.2s ease;
}

.post-entry:hover {
  border-left-color: var(--meta-color);
  background: rgba(0, 0, 0, 0.02);
}

.post-entry h3 {
  font-size: 1.15em;
  margin: 0 0 0.5em 0;
  color: var(--heading-color);
  font-weight: normal;
  transition: color 0.2s ease;
}

.post-entry:hover h3 { color: var(--link-color); }

.post-byline {
  font-style: italic;
  color: var(--meta-color);
  margin-bottom: 0.5em;
  font-size: 0.9em;
}

.post-description {
  color: var(--text-color);
  line-height: 1.5;
  font-size: 0.95em;
}

/* Sequence boxes (homepage groupings) */
.sequence-box {
  display: block;
  text-decoration: none;
  color: var(--text-color);
  background: var(--code-bg);
  padding: 1.5em;
  margin-bottom: 2em;
  border-left: 3px solid transparent;
  transition: all 0.2s ease;
  cursor: pointer;
}

.sequence-box:hover {
  border-left-color: var(--meta-color);
  background: rgba(0, 0, 0, 0.02);
}

.sequence-title {
  position: relative;
  font-size: 1.15em;
  margin: 0 0 0.2em 0;
  padding-right: 3em;
  color: var(--heading-color);
  font-weight: normal;
  transition: color 0.2s ease;
}

.sequence-box:hover .sequence-title { color: var(--link-color); }

.sequence-emoji {
  position: absolute;
  top: 0;
  right: 0;
  font-size: 2.8em;
  line-height: 1;
  opacity: 0.25;
  font-style: normal;
}

.sequence-author {
  font-style: italic;
  color: var(--meta-color);
  margin-bottom: 0.2em;
  font-size: 0.9em;
}

.sequence-author a, .metadata a {
  color: inherit;
  text-decoration: none;
}

.sequence-author a:hover, .metadata a:hover { text-decoration: underline; }

.sequence-date {
  color: var(--meta-color);
  margin-bottom: 1em;
  font-size: 0.9em;
}

/* Post links within a sequence box */
.sequence-posts {
  display: flex;
  flex-direction: column;
  gap: 0.2em;
  padding-top: 0.5em;
  border-top: 1px solid var(--border-color);
}

.post-link {
  color: var(--text-color);
  text-decoration: none;
  padding: 0.2em 0;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.9em;
  transition: color 0.2s ease;
}

.post-link:last-child { border-bottom: none; }
.post-link:hover      { color: var(--link-color); }

/* Comments section */
.comments {
  margin-top: 3em;
  padding-top: 2em;
}

/* === questions.css === */
/* Open question boxes, oq-group overrides, see-all links, sequence TOC, back-to-top */

.question-box {
  border: 2px solid rgb(128, 128, 128);
  padding: 1em;
  margin: 1.5em 0;
  background: var(--code-bg);
}

.question-box p { margin: 0; }

/* oq-group: sequence-box variant on the open-questions page (non-clickable) */
.oq-group { cursor: default; }

.oq-group:hover {
  border-left-color: transparent;
  background: var(--code-bg);
}

.oq-group .sequence-title        { color: var(--heading-color); }
.oq-group:hover .sequence-title  { color: var(--heading-color); }

/* Question links container */
.oq-links {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.82em;
  color: var(--meta-color);
  margin-top: -1.8em;
  margin-bottom: 1.5em;
}

/* "See question in context" / "See all open questions" link (left side - navigation) */
.oq-see-all {
  text-align: left;
}

.oq-see-all a              { color: inherit; text-decoration: none; }
.oq-see-all a:hover        { text-decoration: underline; }

/* Discussion page link (right side - less prominent) */
.oq-discussion {
  text-align: right;
}

.oq-discussion a           { color: inherit; text-decoration: none; }
.oq-discussion a:hover     { text-decoration: underline; }

/* Source attribution on open-questions page */
.oq-source              { font-size: 0.85em; color: var(--meta-color); }
.oq-source a            { color: inherit; text-decoration: none; }
.oq-source a:hover      { text-decoration: underline; }

/* Sequence TOC at the end of each post */
.sequence-toc {
  margin: 3em 0 2em 0;
  padding: 1.5em;
  background: var(--code-bg);
  border: 1px solid var(--border-color);
}

.sequence-toc h3 {
  margin-top: 0;
  margin-bottom: 1em;
  border-bottom: none;
  padding-bottom: 0;
}

.sequence-toc ol  { margin: 0; padding-left: 1.5em; }
.sequence-toc li  { margin-bottom: 0.3em; }
.sequence-toc a   { text-decoration: none; }
.sequence-toc a:hover { text-decoration: underline; }

/* Back-to-top arrow */
.back-to-top         { text-align: center; margin-top: 1em; }
.back-to-top a       { font-size: 1.5em; color: var(--meta-color); text-decoration: none; }
.back-to-top a:hover { color: var(--link-hover); }

/* === theme.css === */
/* Dark-mode component overrides (beyond CSS-variable swaps in variables.css) */

[data-theme="dark"] .post-entry:hover {
  background: rgba(255, 255, 255, 0.02);
}

[data-theme="dark"] .sequence-box:hover {
  background: rgba(255, 255, 255, 0.02);
}

/* === media.css === */
/* Print styles and responsive breakpoints */

@media print {
  body {
    font-size: 12pt;
    max-width: 100%;
    color: black;
    background: white;
  }

  a {
    color: black;
    text-decoration: underline;
  }

  nav, .comments, footer { display: none; }
}

@media (max-width: 768px) {
  body {
    font-size: 16px;
    padding: 1em;
  }

  p { text-align: left; }

  h1 { font-size: 1.5em; }
  h2 { font-size: 1.25em; }
  h3 { font-size: 1.1em; }

  .about-section ul { grid-template-columns: 1fr; }

  .post-entry      { padding: 1em; }
  .post-entry h3   { font-size: 1.05em; }

  .font-toggle {
    font-size: 0.65em;
    padding: 0.3em 0.5em;
    top: 0.3em;
    right: 0.5em;
  }

  .home-glyph   { top: 1.2em; right: 3em; }
  .theme-toggle { top: 1.4em; right: 1em; }
}