:root {
  --ink: #2b2620;
  --muted: #6b6153;
  --border: #c9bfa4;
  --accent: #0000ee;
  --accent-visited: #551a8b;
  --bg: #ffffff;
  --bg-raised: #f4f2ec;
  --max-width: 800px;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
}

body {
  margin: 0;
  font-family: Georgia, Cambria, "Times New Roman", Times, serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
  font-size: 17px;
}

a { color: var(--accent); }
a:visited { color: var(--accent-visited); }

/* ---- Reading progress ---- */

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: transparent;
  z-index: 50;
}

#reading-progress-bar {
  height: 100%;
  width: 0%;
  background: var(--ink);
  transition: width 0.1s linear;
}

/* ---- Header ---- */

.site-header {
  max-width: 1600px;
  margin: 0 auto;
  padding: 20px 32px 0;
}

.about-block {
  display: flex;
  align-items: center;
  gap: 18px;
  margin-bottom: 8px;
}

.profile-photo {
  width: 72px;
  height: 72px;
  object-fit: cover;
  flex-shrink: 0;
}

.site-name {
  font-size: 1rem;
  font-weight: normal;
  letter-spacing: normal;
  margin: 0;
}

.site-tagline {
  margin: 4px 0 0;
  font-size: 1rem;
  color: var(--ink);
  font-style: normal;
}

.site-nav {
  display: flex;
  gap: 22px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--ink);
}

.nav-link {
  background: none;
  border: none;
  font-family: inherit;
  font-size: 0.88rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  text-decoration: underline;
  padding: 7px 0;
  cursor: pointer;
}

.nav-link:hover {
  color: var(--accent-visited);
}

.nav-link.active {
  color: var(--accent-visited);
  font-weight: bold;
}

.nav-link-about {
  margin-left: auto;
}

/* ---- Main content ---- */

#content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 24px 24px 90px;
}

body.note-reading #content,
body.project-reading #content {
  max-width: 1180px;
}

.panel { display: none; }
.panel.active { display: block; }

.panel h2 {
  font-size: 1.3rem;
  font-weight: normal;
  margin: 0 0 12px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--border);
}

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

.entry-placeholder {
  color: var(--muted);
  font-style: italic;
}

/* ---- Notes list ---- */

.notes-list {
  display: flex;
  flex-direction: column;
}

.notes-list[hidden],
.notes-detail[hidden] {
  display: none;
}

.note-item {
  display: block;
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  border-bottom: 1px solid var(--border);
  padding: 20px 4px;
  cursor: pointer;
  font-family: inherit;
}

.note-item:hover {
  background: var(--bg-raised);
}

.note-item:hover .note-item-title {
  color: var(--accent-visited);
}

.note-item-title {
  font-size: 1.15rem;
  margin: 0 0 6px;
  color: var(--accent);
  text-decoration: underline;
}

.note-item-meta {
  font-size: 0.85rem;
  color: var(--muted);
  margin: 0 0 8px;
  font-variant: small-caps;
  letter-spacing: 0.05em;
}

.note-item-summary {
  font-size: 0.95rem;
  color: var(--muted);
  margin: 0;
}

/* ---- Note detail ---- */

.back-link {
  background: none;
  border: none;
  font-family: inherit;
  font-size: 0.85rem;
  color: var(--accent);
  text-decoration: underline;
  cursor: pointer;
  padding: 0 0 10px;
}

.back-link:hover {
  color: var(--accent-visited);
}

.note-title {
  font-size: 1.4rem;
  font-weight: normal;
  margin: 0 0 10px;
}

.note-downloads {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 14px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border);
}

.note-downloads a {
  font-size: 0.9rem;
  color: var(--ink);
  text-decoration: none;
  border: 1px solid var(--ink);
  padding: 9px 16px;
  background: var(--bg-raised);
}

.note-downloads a:hover {
  background: var(--ink);
  color: var(--bg);
}

.download-count {
  color: var(--muted);
  font-size: 0.85em;
}

.note-downloads a:hover .download-count {
  color: var(--bg-raised);
}

.pdf-viewer {
  display: flex;
  flex-direction: column;
  background: var(--bg-raised);
  border: 1px solid var(--ink);
  box-shadow: 6px 6px 0 var(--border);
}

.pdf-toolbar {
  flex: 0 0 auto;
  position: sticky;
  top: 0;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 8px 16px;
  background: var(--bg-raised);
  border-bottom: 1px solid var(--ink);
  font-size: 0.85rem;
  color: var(--muted);
}

.pdf-toolbar-zoom,
.pdf-toolbar-page {
  display: flex;
  align-items: center;
  gap: 8px;
}

.pdf-zoom-btn {
  font-family: inherit;
  font-size: 0.85rem;
  width: 24px;
  height: 24px;
  line-height: 1;
  border: 1px solid var(--ink);
  background: var(--bg);
  color: var(--ink);
  cursor: pointer;
  padding: 0;
}

.pdf-zoom-btn:hover {
  background: var(--ink);
  color: var(--bg);
}

.pdf-zoom-level {
  min-width: 3.4em;
  text-align: center;
}

.pdf-viewer-body {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 22px;
  padding: 22px 0 10px;
  overflow-x: auto;
}

.pdf-viewer-body canvas {
  display: block;
  height: auto;
  background: #fff;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.25);
}

.pdf-viewer-body .pdf-status {
  padding: 40px 0;
  color: var(--muted);
  font-style: italic;
}

/* ---- Comments ---- */

.comments {
  margin-top: 30px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
}

.comments-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}

.comments-title {
  font-size: 1.05rem;
  font-weight: bold;
  margin: 0;
}

.comments-sort {
  font-size: 0.85rem;
  color: var(--muted);
}

.comments-sort select {
  font-family: inherit;
  font-size: 0.85rem;
  color: var(--ink);
  background: var(--bg);
  border: 1px solid var(--border);
  padding: 3px 4px;
  margin-left: 4px;
}

.comments-list {
  margin-bottom: 20px;
}

.comments-empty {
  color: var(--muted);
  font-style: italic;
}

.comment {
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
}

.comment-replies .comment {
  border-bottom: none;
  border-top: 1px solid var(--border);
}

.comment-meta {
  margin: 0 0 4px;
  font-size: 0.85rem;
  color: var(--muted);
}

.comment-body {
  margin: 0 0 6px;
  white-space: pre-wrap;
}

.comment-actions {
  display: flex;
  align-items: center;
  gap: 6px;
}

.vote-btn,
.reply-btn {
  font-family: inherit;
  font-size: 0.8rem;
  color: var(--muted);
  background: none;
  border: 1px solid var(--border);
  padding: 3px 8px;
  cursor: pointer;
}

.vote-btn:hover:not(:disabled),
.reply-btn:hover {
  color: var(--ink);
  border-color: var(--ink);
}

.vote-btn:disabled {
  cursor: default;
  opacity: 0.7;
}

.reply-btn {
  margin-left: auto;
}

.comment-replies {
  margin-top: 10px;
  margin-left: 20px;
  padding-left: 14px;
  border-left: 2px solid var(--border);
}

.reply-form-wrap {
  margin-top: 10px;
}

.reply-form-wrap .comment-form {
  max-width: 420px;
}

.comment-form {
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-width: 480px;
}

.comment-form input,
.comment-form textarea {
  font-family: inherit;
  font-size: 1rem;
  padding: 6px 8px;
  border: 1px solid var(--ink);
  background: var(--bg);
  color: var(--ink);
}

.comment-form button {
  align-self: flex-start;
  font-family: inherit;
  font-size: 0.9rem;
  color: var(--ink);
  border: 1px solid var(--ink);
  padding: 8px 16px;
  background: var(--bg-raised);
  cursor: pointer;
}

.comment-form button:hover {
  background: var(--ink);
  color: var(--bg);
}

.comment-form button:disabled {
  opacity: 0.6;
  cursor: default;
}

.comment-status {
  color: var(--accent);
  font-size: 0.85rem;
  margin: 0;
}

/* ---- Project pages ---- */

.project-text,
.project-figure,
.project-table-wrap {
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
}

.project-text h1 {
  font-size: 1.6rem;
  font-weight: normal;
  margin: 0 0 6px;
}

.project-text h2 {
  font-size: 1.25rem;
  font-weight: normal;
  margin: 2em 0 0.6em;
}

.project-text p {
  margin: 1em 0;
}

.project-meta {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0 0 20px;
}

.equation {
  text-align: center;
  font-style: italic;
  font-size: 1.05rem;
  margin: 1.4em 0;
}

.project-figure {
  margin-top: 1.6em;
  margin-bottom: 1.6em;
  text-align: center;
}

.project-figure img {
  max-width: 100%;
}

.project-figure figcaption {
  margin-top: 8px;
  font-size: 0.85rem;
  color: var(--muted);
}

.project-iframe-wrap {
  margin: 1.8em 0;
}

.project-iframe-caption {
  font-size: 0.92rem;
  font-style: italic;
  text-align: center;
  color: var(--muted);
  margin: 10px auto 0;
  max-width: 640px;
}

.project-iframe {
  display: block;
  width: 100%;
  border: none;
}

.project-table-wrap {
  margin-top: 1.6em;
  margin-bottom: 1.6em;
  overflow-x: auto;
}

.project-table-wrap table {
  border-collapse: collapse;
  width: 100%;
  font-size: 0.9rem;
}

.project-table-wrap th,
.project-table-wrap td {
  border: 1px solid var(--border);
  padding: 8px 10px;
  text-align: left;
}

.project-collapsible {
  max-width: 760px;
  margin: 1.6em auto;
}

.project-collapsible-toggle {
  font-family: inherit;
  font-size: 0.95rem;
  background: none;
  border: none;
  color: var(--accent);
  text-decoration: underline;
  cursor: pointer;
  padding: 0;
}

.project-collapsible-toggle:hover {
  color: var(--accent-visited);
}

/* ---- Floating PDF modal ---- */

.pdf-modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(43, 38, 32, 0.55);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 28px;
}

.pdf-modal-backdrop[hidden] {
  display: none;
}

.pdf-modal {
  width: 100%;
  max-width: 900px;
  height: 88vh;
  background: var(--bg);
  border: 1px solid var(--ink);
  box-shadow: 8px 8px 0 rgba(0, 0, 0, 0.3);
  display: flex;
  flex-direction: column;
}

.pdf-modal-header {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 18px;
  background: var(--bg-raised);
  border-bottom: 1px solid var(--ink);
}

.pdf-modal-title {
  font-style: italic;
  font-size: 0.95rem;
}

.pdf-modal-tools {
  display: flex;
  align-items: center;
  gap: 18px;
  font-size: 0.85rem;
  color: var(--muted);
}

.pdf-modal-close {
  flex-shrink: 0;
  font-family: inherit;
  font-size: 0.85rem;
  background: none;
  border: none;
  color: var(--accent);
  text-decoration: underline;
  cursor: pointer;
  padding: 0;
}

.pdf-modal-close:hover {
  color: var(--accent-visited);
}

.pdf-modal-body {
  flex: 1;
  min-height: 0;
  overflow-y: auto;
}

body.modal-open {
  overflow: hidden;
}

@media (max-width: 700px) {
  .pdf-modal-backdrop { padding: 0; }
  .pdf-modal { max-width: none; height: 100vh; }
  .pdf-modal-header { flex-wrap: wrap; row-gap: 8px; }
}

.project-table-note {
  font-size: 0.82rem;
  color: var(--muted);
  font-style: italic;
  margin-top: 6px;
}

/* ---- Project layout: sticky left contents pane ---- */

.project-layout {
  display: flex;
  align-items: flex-start;
  gap: 44px;
}

.project-main {
  flex: 1;
  min-width: 0;
}

.project-nav {
  flex: 0 0 180px;
  display: flex;
  flex-direction: column;
  gap: 2px;
  position: sticky;
  top: 16px;
  max-height: calc(100vh - 32px);
  overflow-y: auto;
  padding-right: 18px;
  border-right: 1px solid var(--border);
}

.project-nav button {
  font-family: inherit;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  text-align: left;
  background: none;
  border: none;
  border-left: 2px solid transparent;
  color: var(--muted);
  cursor: pointer;
  padding: 5px 0 5px 10px;
}

.project-nav button:hover {
  color: var(--ink);
}

.project-nav button.active {
  color: var(--accent);
  border-left-color: var(--accent);
}

@media (max-width: 860px) {
  .project-layout {
    flex-direction: column;
    gap: 20px;
  }

  .project-nav {
    flex-direction: row;
    flex-wrap: wrap;
    gap: 4px 16px;
    position: static;
    max-height: none;
    overflow: visible;
    width: 100%;
    padding: 10px 0;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }

  .project-nav button {
    border-left: none;
    border-bottom: 2px solid transparent;
    padding: 4px 0;
  }

  .project-nav button.active {
    border-left-color: transparent;
    border-bottom-color: var(--accent);
  }
}

/* ---- Project chapters, TL;DR, stats ---- */

.project-chapter {
  max-width: 760px;
  margin: 3em auto 1em;
  display: flex;
  align-items: baseline;
  gap: 16px;
  scroll-margin-top: 20px;
}

.project-chapter-number {
  font-size: 2.2rem;
  font-weight: normal;
  color: var(--border);
  line-height: 1;
  flex-shrink: 0;
}

.project-chapter-title {
  font-size: 1.4rem;
  font-weight: normal;
  margin: 0;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--ink);
  flex: 1;
}

.project-tldr {
  max-width: 760px;
  margin: 1.6em auto;
  padding: 16px 20px;
  border: 1px solid var(--ink);
  background: var(--bg-raised);
}

.project-tldr-label {
  margin: 0 0 8px;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.project-tldr ul {
  margin: 0;
  padding-left: 1.2em;
}

.project-tldr li {
  margin: 0.4em 0;
}

.project-stat {
  max-width: 760px;
  margin: 1.6em auto;
  padding-left: 18px;
  border-left: 3px solid var(--border);
}

.project-stat-value {
  font-size: 1.5rem;
  font-style: italic;
  margin: 0;
}

.project-stat-label {
  margin: 2px 0 0;
  font-size: 0.95rem;
  color: var(--muted);
}

@media (max-width: 600px) {
  .about-block { gap: 14px; }
  .profile-photo { width: 60px; height: 60px; }
  .site-nav { gap: 16px; flex-wrap: wrap; }
}