/* --- Reset & Base --- */

/* Post thumbnail */
.post-thumbnail { max-width: 120px; height: auto; flex-shrink: 0; object-fit: cover; border-radius: 4px; }
/* Ensure thumbnails inside post content fill width without cropping and retain lightbox */
.post-content img.post-thumbnail { max-width: 100%; height: auto; margin: 0 auto 1rem; display: block; }
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --color-text: #2c2c2c;
  --color-text-light: #6b6b6b;
  --color-link: #2d5016;
  --color-link-hover: #3d6b22;
  --color-bg: #fdfcf9;
  --color-bg-alt: #f5f3ee;
  --color-accent: #2d5016;
  --color-border: #ddd8cc;
  --font-body: "Source Serif 4", Georgia, "Times New Roman", serif;
  --font-heading: "Inter", "Helvetica Neue", Arial, sans-serif;
  --max-width: 780px;
  --color-tag-bg: #e8f0e2;
}

[data-theme="dark"] {
  --color-text: #e0ddd6;
  --color-text-light: #9a9690;
  --color-link: #6aad45;
  --color-link-hover: #82c55e;
  --color-bg: #1a1a1a;
  --color-bg-alt: #242424;
  --color-accent: #6aad45;
  --color-border: #3a3a3a;
  --color-tag-bg: #2a3a20;
}

html { font-size: 17px; scroll-behavior: smooth; }

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

a {
  color: var(--color-link);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s;
}
a:hover { border-bottom-color: var(--color-link-hover); }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.3;
  margin: 2.5em 0 0.8em;
  color: var(--color-text);
}
h1 { font-size: 1.8rem; margin-top: 0; }
h2 { font-size: 1.4rem; border-bottom: 1px solid var(--color-border); padding-bottom: 0.3em; margin-top: 2em; }
h3 { font-size: 1.15rem; margin-top: 1.8em; }
.mobile-page-title { display:none; }

p { margin: 0.7em 0; }

ul, ol { margin: 0.5em 0 0.5em 1.5em; }
li { margin: 0.3em 0; }

table { border-collapse: collapse; margin: 1em 0; width: 100%; }
.table-wrap { overflow-x: auto; overflow-y: hidden; -webkit-overflow-scrolling: touch; margin: 1em 0; }
th, td { border: 1px solid var(--color-border); padding: 0.5em 0.8em; text-align: left; }
th { background: var(--color-bg-alt); font-family: var(--font-heading); font-weight: 600; }

/* --- Layout --- */
.wrapper {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* --- Desktop Header --- */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 50;
}
.site-header .wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 0.8rem;
  padding-bottom: 0.8rem;
}
.site-title {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.03em;
  border-bottom: none !important;
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
}
.site-logo {
  width: 1.4em;
  height: 1.4em;
  border-radius: 3px;
}
.site-nav {
  display: flex;
  align-items: center;
  gap: 1.2em;
}
.site-nav a {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  color: var(--color-text-light);
  border-bottom: none !important;
  transition: color 0.15s;
}
.site-nav a:hover { color: var(--color-accent); }

/* --- Sidebar (mobile only) --- */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: 200px;
  height: 100vh;
  height: 100dvh;
  background: var(--color-accent);
  color: #fff;
  z-index: 100;
  transform: translateX(-100%);
  transition: transform 0.25s ease;
  display: flex;
  flex-direction: column;
  padding: 1rem 1.2rem;
  padding-bottom: calc(1rem + env(safe-area-inset-bottom, 0px));
  overflow-y: auto;
  box-sizing: border-box;
}
.sidebar.open {
  transform: translateX(0);
}
.sidebar-title {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  border-bottom: none !important;
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
  margin-bottom: 0.8rem;
}
.sidebar-nav {
  display: flex;
  flex-direction: column;
}
.sidebar-nav a {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  color: rgba(255,255,255,0.75);
  transition: color 0.15s;
  padding: 0.5em 0;
  border-bottom: 1px solid rgba(255,255,255,0.8);
}
.sidebar-nav a:last-child {
  border-bottom: none;
}
.sidebar-nav a:hover { color: #fff; border-bottom-color: rgba(255,255,255,0.8); }
.sidebar-bottom {
  margin-top: auto;
  padding-top: 0.6rem;
  display: flex;
  flex-direction: column;
  gap: 0.6em;
  flex-shrink: 0;
}
.sidebar-actions {
  display: flex;
  gap: 0.5em;
  align-items: center;
}
.sidebar-contact {
  display: flex;
  align-items: center;
  gap: 0.4em;
  font-family: var(--font-heading);
  font-size: 0.7rem;
  color: rgba(255,255,255,0.6);
  border-bottom: none !important;
  transition: color 0.15s;
}
.sidebar-contact:hover { color: #fff; }
.sidebar-contact span { word-break: break-all; }


/* --- Scroll Fade-In --- */
.fade-in {
  opacity: 0;
  transform: translateY(1.2em);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Home Hero --- */
.home-hero {
  padding: 4rem 0 2rem;
  text-align: center;
}
.lab-icon {
  width: 80px;
  height: 80px;
  display: block;
  margin: 0 auto 0.5em;
}
.lab-title {
  font-family: var(--font-heading);
  font-size: 3rem;
  font-weight: 700;
  color: var(--color-accent);
  letter-spacing: -0.02em;
  margin-bottom: 0.2em;
}
.lab-tagline {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  color: var(--color-text-light);
  font-style: italic;
  margin: 0 0 0.8em;
}
.tagline-highlight {
  position: relative;
  padding: 0 0.15em;
  border-radius: 2px;
}
.tagline-highlight::after {
  content: '';
  position: absolute;
  inset: 0;
  background: #00ff36;
  border-radius: 2px;
  z-index: -1;
  clip-path: inset(0 100% 0 0);
}
.tagline-highlight.highlighted::after {
  clip-path: inset(0 0 0 0);
  transition: clip-path 0.95s ease;
}
[data-theme="dark"] .tagline-highlight::after {
  background: #00ff36;
}
.tagline-char {
  opacity: 0;
  transition: opacity 0.05s;
}
.tagline-char.visible {
  opacity: 1;
}
.tagline-author {
  font-size: 0.85rem;
  color: var(--color-text-light);
  font-style: italic;
  display: inline-block;
  margin-left: 0;
}
.lab-description {
  font-size: 1rem;
  color: var(--color-text-light);
  max-width: 520px;
  margin: 0 auto;
}

/* --- Recent Posts --- */
.recent-posts {
  padding: 0.5rem 0;
}
.recent-posts h2 {
  margin-bottom: 0.5em;
}

/* --- Search --- */
.page-title-row {
  display: flex;
  align-items: center;
  gap: 0.8em;
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 0.3em;
  margin-bottom: 0.3em;
}
.page-title-row .page-title { margin-bottom: 0; border-bottom: none; }
.rss-subscribe {
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
  font-family: var(--font-heading);
  font-size: 0.85rem;
  color: var(--color-link);
  margin-left: auto;
}
.rss-subscribe svg { flex-shrink: 0; }
.rss-subscribe a {
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
  color: var(--color-link);
  border-bottom: none !important;
  transition: color 0.15s;
}
.rss-subscribe a:hover { color: var(--color-link-hover); }

/* --- RSS Guide --- */
.rss-guide h2 { font-size: 1.1rem; margin-top: 1.8em; border-bottom: none; padding-bottom: 0; }
.section-title-row { display: flex; align-items: center; gap: 0.4em; }
.section-title-row svg { color: var(--color-text-light); flex-shrink: 0; }
.section-toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  list-style: none;
  padding: 0.5em 0;
  border-bottom: 1px solid var(--color-border);
}
.section-toggle::-webkit-details-marker { display: none; }
.section-toggle::marker { display: none; content: ""; }
.section-toggle h2 { margin: 0; }
.toggle-chevron {
  color: var(--color-text-light);
  transition: transform 0.2s ease;
  flex-shrink: 0;
}
details[open] > .section-toggle .toggle-chevron {
  transform: rotate(180deg);
}
.section-content {
  overflow: hidden;
  transition: height 0.3s ease, opacity 0.25s ease;
  padding-top: 0.8em;
}
.rss-guide details {
  margin-bottom: 0;
}
.rss-guide details + details {
  margin-top: 0;
}
.rss-url-box {
  display: flex;
  align-items: center;
  gap: 0.6em;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 0.5em 0.8em;
  margin: 1em 0;
}
.rss-url-box code { font-size: 0.88rem; word-break: break-all; background: none; padding: 0; }
.rss-copy-btn {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  padding: 0.3em 0.8em;
  background: var(--color-accent);
  color: #fff;
  border: none;
  border-radius: 3px;
  cursor: pointer;
  white-space: nowrap;
  flex-shrink: 0;
  transition: opacity 0.15s;
}
.rss-copy-btn:hover { opacity: 0.85; }
.rss-apps {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4em;
  margin: 0.6em 0;
}
.rss-footnote {
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin: 0.3em 0 0 0.2em;
}
.post-content .footnotes {
  font-size: 0.82rem;
  color: var(--color-text-light);
}
.post-content .inline-footnote {
  font-size: 0.82rem;
  color: var(--color-text-light);
  margin: 0.6em 0 0 0;
  line-height: 1.5;
}
.rss-readers-table .info-trigger {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.2em;
  height: 1.2em;
  font-size: 0.7em;
  border: 1.5px solid var(--color-accent);
  border-radius: 50%;
  color: var(--color-accent);
  cursor: pointer;
  vertical-align: middle;
  margin-left: 0.25em;
  position: relative;
}
.rss-readers-table .info-box {
  display: none;
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  margin-top: 0.5em;
  padding: 0.6em 0.9em;
  background: var(--color-bg);
  border: 1px solid var(--color-accent);
  border-radius: 5px;
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--color-text);
  white-space: normal;
  text-align: center;
  width: 18em;
  z-index: 10;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
.rss-readers-table .info-trigger:hover + .info-box,
.rss-readers-table .info-trigger:focus + .info-box {
  display: block;
}
.rss-readers-table th {
  position: relative;
}
.search-box {
  position: relative;
  margin-bottom: 1.5em;
}
.search-box input {
  width: 100%;
  padding: 0.6em 2.2em 0.6em 0.8em;
  font-family: var(--font-heading);
  font-size: 0.95rem;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  background: var(--color-bg);
  color: var(--color-text);
  outline: none;
  transition: border-color 0.2s;
}
.search-box input:focus {
  border-color: var(--color-accent);
}
.search-sort-label {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  color: var(--color-text-light);
  flex-shrink: 0;
}
.search-sort {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  padding: 0.3em 0.5em;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  background: var(--color-bg);
  color: var(--color-text-light);
  cursor: pointer;
  outline: none;
  flex-shrink: 0;
}
.search-sort:focus {
  border-color: var(--color-accent);
}
.search-controls {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5em;
}
.search-controls-left, .search-controls-right {
  display: flex;
  align-items: center;
  gap: 0.4em;
}
.search-clear {
  position: absolute;
  right: 0.6em;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.2rem;
  color: var(--color-text-light);
  cursor: pointer;
  display: none;
  line-height: 1;
}
.search-clear:hover { color: var(--color-text); }
.search-result-count {
  display: block;
  font-family: var(--font-heading);
  font-size: 0.82rem;
  color: var(--color-text-light);
  margin-top: -0.8em;
  margin-bottom: 0.5em;
}
mark.search-highlight {
  background: none;
  color: inherit;
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-decoration-thickness: 2px;
  text-underline-offset: 2px;
}
.pagination {
  display: flex;
  justify-content: center;
  gap: 0.3em;
  margin: 2em 0;
  font-family: var(--font-heading);
}
.page-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.2em;
  padding: 0.3em 0.6em;
  font-size: 0.85rem;
  border: 1px solid var(--color-border);
  border-radius: 3px;
  color: var(--color-text-light);
  text-decoration: none;
  transition: all 0.15s;
}
.page-btn:hover { border-color: var(--color-accent); color: var(--color-accent); }
.page-btn.active { background: var(--color-accent); color: #fff; border-color: var(--color-accent); }
.no-results {
  font-family: var(--font-heading);
  color: var(--color-text-light);
  font-style: italic;
  margin-top: 1em;
}
.post-category-badges {
  margin-left: 0;
}
.post-category-badges .category-tag {
  font-size: 0.7rem;
}
.post-category-badges .hidden-tag {
  display: none;
}
.category-more-toggle {
  cursor: pointer;
  background: var(--color-tag-bg);
  color: var(--color-accent);
  font-style: italic;
}
.category-more-toggle:hover {
  opacity: 0.8;
}

/* --- Category Filters --- */
.category-filters {
  margin-bottom: 1.5em;
}
.cat-filter-btn {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  padding: 0.25em 0.7em;
  border: 1px solid var(--color-border);
  border-radius: 3px;
  background: var(--color-bg);
  color: var(--color-text-light);
  cursor: pointer;
  transition: all 0.15s;
}
.cat-filter-btn:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}
.cat-filter-btn.active {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

/* --- Table of Contents --- */
.toc {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 0.8em 1.2em 0.8em 0.5em;
  margin: 0 0 2em;
}
.toc-title {
  font-family: var(--font-heading);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text-light);
  margin: 0 0 0.3em;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.toc ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
.toc li {
  margin: 0.25em 0;
}
.toc li a {
  font-family: var(--font-heading);
  font-size: 0.88rem;
  color: var(--color-text-light);
  border-bottom: none;
}
.toc li a:hover {
  color: var(--color-accent);
}
.toc .toc-h1 {
  font-weight: 500;
}
.toc .toc-h2 {
  margin-left: 1.5em;
}
.toc .toc-h3 {
  margin-left: 3em;
}

/* --- PDF Download --- */
.pdf-download {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 0.85rem;
  padding: 0.4em 1em;
  border: 1px solid var(--color-accent);
  border-radius: 3px;
  color: var(--color-accent);
  margin-bottom: 1em;
}
.pdf-download:hover {
  background: var(--color-accent);
  color: #fff;
  border-bottom: none;
}

/* --- Post Content Spacing --- */
.post-content h1 {
  margin-top: 3em;
}
.post-content h2 {
  margin-top: 3em;
  font-size: 1.8rem;
  border-bottom: none;
  padding-bottom: 0;
}
.post-content h3 {
  margin-top: 2em;
  font-size: 1.4rem;
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 0.3em;
}
.post-content h4 {
  margin-top: 1.8em;
  font-size: 1.15rem;
}

/* --- Blog List --- */
.blog-list-item {
  font-family: var(--font-heading);
  padding: 0.6em 0;
  border-bottom: 1px solid var(--color-bg-alt);
}
.post-title-row {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin: 0.2em 0;
}
.post-date {
  color: var(--color-text-light);
  font-size: 0.85rem;
}
.post-title-link {
  font-size: 1.05rem;
  color: var(--color-accent);
}
.post-title-link.post-visited {
  color: #8fa87a;
}
.post-excerpt {
  font-family: var(--font-body);
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin: 0.3em 0 0;
}
.more-link {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  margin-top: 1em;
}

/* --- Post --- */
.post { padding: 2rem 0 3rem; }
.math-scroll { overflow-x: auto; overflow-y: hidden; -webkit-overflow-scrolling: touch; margin: 1em 0; }
.post-header { margin-bottom: 1.5em; }
.post-title {
  font-size: 2rem;
  font-weight: 700;
  font-family: var(--font-heading);
  margin-bottom: 0.3em;
  line-height: 1.2;
}
.post-meta {
  font-family: var(--font-heading);
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.post-meta-left {
  display: flex;
  align-items: center;
  gap: 0.8em;
}
.post-modified {
  color: var(--color-text-light);
  white-space: nowrap;
}
.post-series-info {
  font-family: var(--font-heading);
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin-top: 0.2em;
}
.post-series-info strong {
  color: var(--color-text);
}
.series-label {
  color: var(--color-text-light);
}
.post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4em;
  margin-top: 0.3em;
}
.category-tag {
  display: inline-block;
  background: var(--color-tag-bg);
  color: var(--color-accent);
  padding: 0.15em 0.6em;
  border-radius: 3px;
  font-size: 0.8rem;
  margin-right: 0.35em;
  border-bottom: none;
  cursor: pointer;
}
.category-tag:hover {
  background: var(--color-accent);
  color: var(--color-bg);
  border-bottom: none;
}
/* --- Format Badges --- */
.format-badge {
  display: inline-block;
  padding: 0.15em 0.6em;
  border-radius: 12px;
  font-size: 0.75rem;
  font-family: var(--font-heading);
  font-weight: 600;
  letter-spacing: 0.03em;
  margin-right: 0.35em;
  border-bottom: none;
  text-transform: capitalize;
  vertical-align: middle;
  text-decoration: none;
  cursor: pointer;
  border: 1.5px solid;
}
.format-badge.format-essay {
  background: transparent;
  color: #2e7d32;
  border-color: #2e7d32;
}
.format-badge.format-tutorial {
  background: transparent;
  color: #1565c0;
  border-color: #1565c0;
}
.format-badge.format-deep-dive {
  background: transparent;
  color: #7b1fa2;
  border-color: #7b1fa2;
}
.format-badge.format-essay:hover {
  background: #2e7d32;
  color: #fff;
}
.format-badge.format-tutorial:hover {
  background: #1565c0;
  color: #fff;
}
.format-badge.format-deep-dive:hover {
  background: #7b1fa2;
  color: #fff;
}
[data-theme="dark"] .format-badge.format-essay {
  color: #66bb6a;
  border-color: #66bb6a;
}
[data-theme="dark"] .format-badge.format-tutorial {
  color: #64b5f6;
  border-color: #64b5f6;
}
[data-theme="dark"] .format-badge.format-deep-dive {
  color: #ce93d8;
  border-color: #ce93d8;
}
[data-theme="dark"] .format-badge.format-essay:hover {
  background: #66bb6a;
  color: #1a1a1a;
}
[data-theme="dark"] .format-badge.format-tutorial:hover {
  background: #64b5f6;
  color: #1a1a1a;
}
[data-theme="dark"] .format-badge.format-deep-dive:hover {
  background: #ce93d8;
  color: #1a1a1a;
}
.post-category-badges .format-badge {
  font-size: 0.7rem;
}
/* --- Filter Rows --- */
.filter-row {
  display: flex;
  align-items: flex-start;
  gap: 0.5em;
  margin-bottom: 0.5em;
}
.filter-label {
  font-family: var(--font-heading);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-text-light);
  white-space: nowrap;
}
.filter-row-center {
  align-items: center;
}
.filter-row-center .filter-label {
  line-height: 1;
}
.filter-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4em;
}
.fmt-filter-btn {
  font-family: var(--font-heading);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  padding: 0.15em 0.6em;
  border-radius: 12px;
  cursor: pointer;
  text-transform: capitalize;
  background: transparent;
}
.fmt-filter-btn.format-essay.active {
  background: #2e7d32;
  color: #fff;
}
.fmt-filter-btn.format-tutorial.active {
  background: #1565c0;
  color: #fff;
}
.fmt-filter-btn.format-deep-dive.active {
  background: #7b1fa2;
  color: #fff;
}
[data-theme="dark"] .fmt-filter-btn.format-essay.active {
  background: #66bb6a;
  color: #1a1a1a;
}
[data-theme="dark"] .fmt-filter-btn.format-tutorial.active {
  background: #64b5f6;
  color: #1a1a1a;
}
[data-theme="dark"] .fmt-filter-btn.format-deep-dive.active {
  background: #ce93d8;
  color: #1a1a1a;
}
.post-footer { margin-top: 2em; }
.post-abstract {
  font-style: italic;
  color: var(--color-text-light);
  font-size: 0.95rem;
  margin: 0.8em 0 1.5em;
  padding: 0.8em 1em;
  border-left: 3px solid var(--color-accent);
  background: var(--color-bg-alt);
  border-radius: 0 4px 4px 0;
}
.post-nav {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-heading);
  font-size: 0.9rem;
  gap: 1em;
}
.post-nav-prev, .post-nav-next {
  width: 40%;
}
.post-nav-prev { text-align: left; }
.post-nav-next { text-align: right; margin-left: auto; }

/* --- Pages --- */
.page { padding: 2rem 0 3rem; }
.page-title {
  font-size: 1.8rem;
  margin-bottom: 0.3em;
  padding-bottom: 0.3em;
  border-bottom: 1px solid var(--color-border);
}

/* --- Footer --- */
/* Override max-height for post content thumbnails */
.post-content img.post-thumbnail { max-height: none; }
/* Ensure thumbnail images are clickable for lightbox */
.post-content img.figure-img, .post-content img.post-thumbnail { cursor: zoom-in; }
.site-footer {
  margin-top: auto;
  border-top: 1px solid var(--color-border);
  padding: 1.5rem 0;
  text-align: center;
  background: var(--color-bg-alt);
}
.footer-contact {
  display: flex;
  justify-content: center;
  gap: 0.8em;
  margin-bottom: 0.5em;
}
.footer-contact a {
  text-decoration: none;
  border-bottom: none;
}
.footer-text {
  font-family: var(--font-heading);
  font-size: 0.75rem;
  color: var(--color-text-light);
  margin: 0;
}

/* --- Figures --- */

.page-content a[href^="mailto:"] {
  color: var(--color-accent);
}
figure, .figure-caption {
  text-align: center;
  margin: 2em auto;
}
img.figure-img {
  display: block;
  max-width: 550px;
  width: 100%;
  margin: 0 auto;
}
.figure-caption {
  font-family: var(--font-heading);
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin-top: 0.6em;
  margin-bottom: 2em;
}

/* --- Dark Mode Toggle --- */
.subscribe-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-light);
  border-bottom: none !important;
  padding: 0.3em;
  line-height: 1;
}
.subscribe-icon:hover {
  color: var(--color-accent);
}
.subscribe-icon svg {
  width: 20px;
  height: 20px;
}
.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.3em;
  color: var(--color-text-light);
  border-bottom: none !important;
  line-height: 1;
  text-align: left;
}
.theme-toggle:hover { color: var(--color-accent); }
.theme-toggle svg { width: 20px; height: 20px; }
.theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }
[data-theme="dark"] .theme-toggle .icon-sun { display: inline; }

/* --- Sidebar theme overrides (white icons) --- */
.sidebar .theme-toggle {
  color: rgba(255,255,255,0.6);
}
.sidebar .theme-toggle:hover { color: #fff; }
.sidebar .subscribe-icon {
  color: rgba(255,255,255,0.6);
}
.sidebar .subscribe-icon:hover { color: #fff; }

/* --- Hamburger Toggle (mobile only) --- */
.sidebar-toggle {
  display: none;
}

.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.3);
  z-index: 90;
}
.sidebar-overlay.active { display: block; }

/* --- Reading Progress Bar --- */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: var(--color-accent);
  z-index: 1000;
  transition: width 0.1s linear;
  width: 0%;
}

/* --- Back to Top --- */
.back-to-top {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--color-accent);
  color: #fff;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.3s, transform 0.3s;
  z-index: 50;
  border-bottom: none !important;
}
.back-to-top.visible {
  opacity: 1;
  transform: translateY(0);
}
.back-to-top:hover {
  opacity: 0.85;
}
.back-to-top svg { width: 20px; height: 20px; }

/* --- Reading Time --- */
.reading-time {
  font-family: var(--font-heading);
  font-size: 0.85rem;
  color: var(--color-text-light);
}

/* --- Share Buttons --- */
.share-bar {
  display: flex;
  flex-direction: column;
  gap: 0.3em;
  margin: 1.5em 0;
  padding-top: 1em;
  border-top: 1px solid var(--color-border);
}
.subscribe-row, .share-row {
  display: flex;
  align-items: center;
  gap: 0.6em;
}
.share-label {
  font-family: var(--font-heading);
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin-right: 0.3em;
}
.share-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  color: var(--color-text-light);
  cursor: pointer;
  transition: all 0.15s;
  border-bottom: none !important;
}
.share-btn:hover {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}
.share-btn svg { width: 16px; height: 16px; fill: currentColor; }
.share-btn.copy-link { position: relative; }
.share-btn .copy-tooltip {
  position: absolute;
  bottom: 110%;
  left: 50%;
  transform: translateX(-50%);
  font-family: var(--font-heading);
  font-size: 0.7rem;
  background: var(--color-text);
  color: var(--color-bg);
  padding: 0.2em 0.5em;
  border-radius: 3px;
  white-space: nowrap;
  opacity: 0;
  transition: opacity 0.2s;
  pointer-events: none;
}
.share-btn .copy-tooltip.show { opacity: 1; }

/* --- Image Lightbox --- */
.lightbox-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.85);
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
  cursor: zoom-out;
}
.lightbox-overlay.open { opacity: 1; pointer-events: auto; }
.lightbox-overlay img {
  max-width: 92vw;
  max-height: 92vh;
  object-fit: contain;
  border-radius: 4px;
}
.lightbox-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: none;
  border: none;
  color: #fff;
  cursor: pointer;
  opacity: 0.7;
  transition: opacity 0.15s;
}
.lightbox-close:hover { opacity: 1; }
.lightbox-close svg { width: 28px; height: 28px; }

/* --- Post Series --- */
.series-badge {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 0.8rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 3px;
  padding: 0.15em 0.6em;
  color: var(--color-accent);
  margin-right: 0.5em;
}
.series-nav {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 0.8em 1.2em;
  margin: 1.5em 0;
}
.series-nav-title {
  font-family: var(--font-heading);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-text-light);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.4em;
}
.series-nav ol {
  margin: 0;
  padding-left: 1.2em;
}
.series-nav li {
  font-family: var(--font-heading);
  font-size: 0.88rem;
  margin: 0.2em 0;
  color: var(--color-text-light);
}
.series-nav li a {
  color: var(--color-link);
}
.series-nav li.current {
  font-weight: 600;
  color: var(--color-text);
}

/* --- Series Page --- */
.series-page-description {
  font-style: italic;
  color: var(--color-text-light);
  margin: 0.5em 0 1em;
}
.series-page-list {
  list-style: none;
  padding: 0;
  margin: 0;
}
.series-page-list li {
  padding: 0.8em 0;
  border-bottom: 1px solid var(--color-bg-alt);
}
.series-page-list li:last-child { border-bottom: none; }
.series-page-list li a {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-accent);
}
.series-page-list li.current a {
  color: var(--color-text);
  pointer-events: none;
}
.series-page-post-meta {
  font-family: var(--font-heading);
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin-top: 0.2em;
}

/* --- Responsive --- */
/* --- 404 Page --- */
.not-found {
  text-align: center;
  padding: 4rem 1rem;
  min-height: 60vh;
  display: flex;
  align-items: center;
  justify-content: center;
}
.not-found-code {
  font-size: 6rem;
  color: var(--color-accent);
  margin-bottom: 0.2em;
  line-height: 1;
  word-break: break-all;
}
.not-found-message {
  font-size: 1.15rem;
  color: var(--color-text);
  margin-bottom: 0.3em;
}
.not-found-hint {
  font-family: var(--font-heading);
  font-size: 0.95rem;
  color: var(--color-text-light);
  font-style: italic;
  margin-bottom: 1.5em;
}
.not-found-home {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 0.95rem;
  padding: 0.6em 1.4em;
  background: var(--color-accent);
  color: #fff;
  text-decoration: none;
  border-radius: 4px;
  border-bottom: none !important;
  transition: opacity 0.15s;
}
.not-found-home:hover { opacity: 0.85; }

/* --- Related Posts --- */

.page-content strong { color: var(--color-accent); }
.page-content strong.no-accent { color: inherit; }
.related-posts {
  margin: 2em 0 0;
  padding-top: 1.5em;
  border-top: 1px solid var(--color-border);
}
.related-posts-title {
  font-family: var(--font-heading);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text-light);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.8em;
}
.related-posts-list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.related-posts-list li {
  margin: 0.5em 0;
  padding: 0.5em 0;
  border-bottom: 1px solid var(--color-bg-alt);
}
.related-posts-list li:last-child { border-bottom: none; }
.related-post-link {
  font-family: var(--font-heading);
  font-size: 1rem;
  color: var(--color-accent);
  display: block;
}
.related-post-meta {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-top: 0.2em;
}

/* --- Code Blocks (base styling, colors in syntax.css) --- */
pre, code { font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace; }
code { font-size: 0.88em; background: var(--color-bg-alt); padding: 0.15em 0.4em; border-radius: 3px; }
pre { margin: 1em 0; overflow-x: auto; }
pre code { background: none; padding: 0; font-size: 0.9rem; border-radius: 0; }

/* --- Responsive --- */

/* Tablet: 601px - 1024px */
@media (min-width: 601px) and (max-width: 1024px) {
  .lab-title { font-size: 2.6rem; }
  .home-hero { padding: 3rem 0 1.5rem; }
  .site-header .wrapper { padding-top: 0.6rem; padding-bottom: 0.6rem; }
  .site-nav { gap: 0.8em; }
  .site-nav a { font-size: 0.85rem; }
  .post-title { font-size: 1.7rem; }
  .wrapper { max-width: 680px; }
}

@media (max-width: 600px) {
  /* Hide desktop header on mobile */
  .site-header { display: none; }

.mobile-page-title { display:flex; align-items:center; justify-content:center; font-family:var(--font-heading); font-size:1.3em; margin-top:-1rem; margin-bottom:0.2rem; }
.mobile-page-title a { color: var(--color-accent); text-decoration: none; border-bottom: none; display: inline-flex; align-items: center; gap: 0.3em; }
.mobile-page-title .site-logo { width:1.2em; height:1.2em; vertical-align:middle; }  /* Show hamburger */
  .sidebar-toggle {
    display: flex;
    position: fixed;
    top: 1rem;
    left: 1rem;
    z-index: 200;
    background: var(--color-accent);
    border: none;
    border-radius: 6px;
    padding: 0.55rem 0.5rem;
    cursor: pointer;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 5px;
    width: 38px;
    height: 38px;
    -webkit-tap-highlight-color: transparent;
    transition: left 0.25s ease;
  }
  .sidebar-toggle.open {
    left: 212px;
  }
  .sidebar-toggle span {
    display: block;
    width: 20px;
    height: 2.5px;
    background: #fff;
    border-radius: 2px;
    transition: transform 0.25s ease, opacity 0.25s ease;
  }
  .sidebar-toggle.open span:nth-child(1) {
    transform: translateY(7.5px) rotate(45deg);
  }
  .sidebar-toggle.open span:nth-child(2) {
    opacity: 0;
  }
  .sidebar-toggle.open span:nth-child(3) {
    transform: translateY(-7.5px) rotate(-45deg);
  }

  .page-content { flex: 1; padding-top: 3rem; }
  .home-hero { padding: 3rem 0 1.5rem; }
  .lab-title { font-size: 2.2rem; }
  html { font-size: 15px; }
  .share-row { display: grid; grid-template-columns: 4.5em repeat(4, 34px); gap: 0.5em; justify-content: start; }
  .share-row .share-btn:nth-child(6) { grid-column: 2; }
  .subscribe-row { display: grid; grid-template-columns: 4.5em repeat(4, 34px); gap: 0.5em; justify-content: start; }
}

/* Hide Giscus branding */
.giscus { min-height: 200px; }

@media (max-width: 600px) {
  .post-meta { flex-wrap: wrap; }
  .post-modified { width: 100%; text-align: left; }
}