/* ===== RESET & BASE ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:           #0d0d1a;
  --sidebar-bg:   #1a1a2e;
  --surface:      #12122a;
  --accent-blue:  #58c4dd;
  --accent-gold:  #ffd700;
  --accent-teal:  #4ecdc4;
  --accent-purple:#c77dff;
  --accent-orange:#ff9f43;
  --accent-red:   #ff6b6b;
  --text:         #e8e8e8;
  --text-muted:   #9999bb;
  --link:         #58c4dd;
  --sidebar-w:    260px;
}

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

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Linux Libertine', Georgia, 'Times New Roman', serif;
  line-height: 1.7;
}

a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

h1, h2, h3, h4, h5, h6 {
  font-family: 'Linux Biolinum', 'Gill Sans', Arial, sans-serif;
  line-height: 1.3;
  margin-top: 1.6em;
  margin-bottom: 0.5em;
}
h1 { font-size: 2rem;   color: #fff; }
h2 { font-size: 1.45rem; color: var(--accent-blue); border-bottom: 1px solid #2a2a4a; padding-bottom: .2em; }
h3 { font-size: 1.2rem; color: var(--accent-teal); }
h4 { font-size: 1.05rem; color: var(--accent-gold); }

p   { margin-bottom: 1em; }
ul, ol { margin: .5em 0 1em 1.8em; }
li  { margin-bottom: .3em; }

code {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: .85em;
  background: #1a1a35;
  border: 1px solid #2a2a55;
  border-radius: 3px;
  padding: .1em .4em;
}
pre code { background: none; border: none; padding: 0; }
pre {
  background: #111128;
  border: 1px solid #2a2a55;
  border-radius: 6px;
  padding: 1em 1.2em;
  overflow-x: auto;
  margin-bottom: 1em;
}

/* ===== LAYOUT ===== */
.layout-wrapper {
  display: flex;
  min-height: 100vh;
}

/* ===== SIDEBAR ===== */
.sidebar {
  width: var(--sidebar-w);
  min-width: var(--sidebar-w);
  background: var(--sidebar-bg);
  border-right: 1px solid #2a2a4a;
  display: flex;
  flex-direction: column;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  padding-bottom: 2em;
}

.sidebar-header {
  padding: 1.2em 1em 1em;
  border-bottom: 1px solid #2a2a4a;
}
.sidebar-title {
  display: block;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--accent-blue);
  font-family: sans-serif;
}
.sidebar-subtitle {
  font-size: .8rem;
  color: var(--text-muted);
  margin-top: .2em;
}

.arc-group { padding: .6em 0; border-bottom: 1px solid #1e1e3a; }
.arc-label {
  font-size: .65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--text-muted);
  padding: .5em 1em .3em;
}

.ep-link {
  display: flex;
  gap: .5em;
  padding: .3em 1em;
  font-size: .82rem;
  color: var(--text-muted);
  transition: background .15s, color .15s;
  align-items: flex-start;
}
.ep-link:hover { background: #1e1e3a; color: var(--text); text-decoration: none; }
.ep-link.active { background: #1e2a45; color: var(--accent-blue); }

.ep-num {
  font-family: monospace;
  font-size: .78rem;
  color: var(--accent-blue);
  min-width: 22px;
  opacity: .7;
  flex-shrink: 0;
  margin-top: .05em;
}
.ep-title { word-break: break-all; line-height: 1.3; }

.sidebar-footer {
  margin-top: auto;
  padding: 1em;
  border-top: 1px solid #2a2a4a;
  display: flex;
  gap: 1em;
  flex-wrap: wrap;
}
.sidebar-footer a {
  font-size: .8rem;
  color: var(--text-muted);
}
.sidebar-footer a:hover { color: var(--text); }

/* ===== MAIN CONTENT ===== */
.main-content {
  flex: 1;
  min-width: 0;
  padding: 2.5em 3em 4em;
  /* no max-width here — episode pages use .episode-layout for 3-col */
}

/* ===== EPISODE 3-COLUMN LAYOUT ===== */
.episode-layout {
  display: flex;
  gap: 0;
  align-items: stretch;
  min-height: 100%;
}

.episode-page {
  flex: 1;
  min-width: 0;
  max-width: 720px;
}

/* Images inside episode content */
.episode-content img {
  display: block;
  max-width: 100%;
  width: auto;
  height: auto;
  margin: 1.4em auto;
  border-radius: 4px;
  background: #0a0a1a;
}

/* Right TOC aside */
.ep-toc-aside {
  width: 210px;
  min-width: 210px;
  padding: 0 0 0 2em;
  flex-shrink: 0;
}

.ep-toc-sticky {
  position: sticky;
  top: 1.5em;
  max-height: calc(100vh - 3em);
  overflow-y: auto;
  padding-bottom: 2em;
}

.ep-toc-label {
  font-size: .68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--text-muted);
  margin-bottom: .6em;
  padding-bottom: .4em;
  border-bottom: 1px solid #2a2a4a;
}

.ep-toc-aside nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
.ep-toc-aside nav li { margin: 0; }
.ep-toc-aside nav a {
  display: block;
  padding: .25em 0 .25em .6em;
  font-size: .78rem;
  color: var(--text-muted);
  border-left: 2px solid transparent;
  line-height: 1.35;
  transition: color .12s, border-color .12s;
}
.ep-toc-aside nav a:hover {
  color: var(--text);
  border-left-color: var(--accent-blue);
  text-decoration: none;
}
/* nested TOC items */
.ep-toc-aside nav ul ul a {
  padding-left: 1.4em;
  font-size: .73rem;
}
.ep-toc-aside nav ul ul ul a {
  padding-left: 2.2em;
  font-size: .7rem;
}

/* ===== EPISODE HEADER ===== */
.episode-header {
  margin-bottom: 2em;
  padding-bottom: 1.2em;
  border-bottom: 2px solid #2a2a4a;
}
.ep-badge {
  display: inline-block;
  background: var(--accent-blue);
  color: #0d0d1a;
  font-family: monospace;
  font-size: .85rem;
  font-weight: 700;
  padding: .2em .6em;
  border-radius: 4px;
  margin-bottom: .5em;
}
.ep-main-title {
  margin-top: .3em;
  margin-bottom: .2em;
  font-size: 1.9rem;
}
.ep-subtitle {
  font-size: 1rem;
  color: var(--text-muted);
  margin-bottom: .8em;
  font-style: italic;
}
.ep-meta {
  display: flex;
  align-items: center;
  gap: 1em;
  flex-wrap: wrap;
  margin-top: .8em;
}
.meta-item { font-size: .85rem; color: var(--text-muted); }
.meta-icon { margin-right: .3em; }
.domain-chip {
  display: inline-block;
  background: #1a1a3a;
  border: 1px solid #3a3a6a;
  border-radius: 4px;
  padding: .15em .55em;
  font-size: .75rem;
  margin-right: .3em;
  color: var(--text-muted);
}

/* ===== CROSS-REFS ===== */
.cross-refs { margin-bottom: 1.5em; }
.cross-refs-title {
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--text-muted);
  margin-bottom: .5em;
}
.ref-cards { display: flex; gap: .5em; flex-wrap: wrap; }
.ref-card {
  display: flex;
  gap: .4em;
  align-items: center;
  padding: .3em .7em;
  border-radius: 4px;
  font-size: .82rem;
  text-decoration: none;
}
.ref-card.callback { background: #0a1525; border: 1px solid #1a3a55; color: var(--accent-blue); }
.ref-card.forward  { background: #15100a; border: 1px solid #3a2a1a; color: var(--accent-orange); }
.ref-card:hover { opacity: .8; text-decoration: none; }
.ref-ep { font-family: monospace; font-size: .75rem; opacity: .7; }

/* .episode-toc removed — TOC is now in right aside (.ep-toc-aside) */

/* ===== THEOREM BLOCKS ===== */
.theorem-block,
.proof-block,
.definition-block,
.music-block,
.proposition-block,
.conjecture-block {
  border-radius: 0 6px 6px 0;
  padding: 1em 1.2em;
  margin: 1.5em 0;
}

.theorem-block     { border-left: 4px solid var(--accent-blue);   background: #0a1220; }
.proof-block       { border-left: 4px solid var(--accent-teal);   background: #081a18; }
.definition-block  { border-left: 4px solid var(--accent-gold);   background: #151000; }
.music-block       { border-left: 4px solid var(--accent-purple);  background: #100818; }
.proposition-block { border-left: 4px solid var(--accent-orange);  background: #150b00; }
.conjecture-block  { border-left: 4px solid var(--accent-red);    background: #150505; }

.block-label {
  font-size: .72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .09em;
  margin-bottom: .6em;
  opacity: .85;
}
.theorem-block .block-label     { color: var(--accent-blue); }
.proof-block .block-label       { color: var(--accent-teal); }
.definition-block .block-label  { color: var(--accent-gold); }
.music-block .block-label       { color: var(--accent-purple); }
.proposition-block .block-label { color: var(--accent-orange); }
.conjecture-block .block-label  { color: var(--accent-red); }

.proof-block::after {
  content: "∎";
  display: block;
  text-align: right;
  color: var(--accent-teal);
  margin-top: .6em;
  font-size: 1.1em;
}

.block-body > *:last-child { margin-bottom: 0; }

/* ===== EPISODE NAV ===== */
.ep-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 3em;
  padding-top: 1.5em;
  border-top: 1px solid #2a2a4a;
  gap: 1em;
}
.ep-nav-prev, .ep-nav-next {
  font-size: .88rem;
  color: var(--text-muted);
  max-width: 45%;
}
.ep-nav-next { margin-left: auto; text-align: right; }

/* ===== HOMEPAGE GRID ===== */
.homepage { padding: 0; }
.hero {
  text-align: center;
  padding: 3em 0 2em;
  border-bottom: 1px solid #2a2a4a;
  margin-bottom: 2.5em;
}
.hero h1 { font-size: 2.8rem; margin-bottom: .3em; }
.hero .tagline { font-size: 1.1rem; color: var(--text-muted); max-width: 560px; margin: 0 auto; }
.hero-avatar {
  width: 96px;
  height: 96px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid #2a2a4a;
  margin-bottom: 1.2em;
  display: block;
  margin-left: auto;
  margin-right: auto;
  transition: border-color .2s;
}
.hero-avatar:hover { border-color: var(--accent-blue); }

.arc-section { margin-bottom: 2.5em; }
.arc-section h2 { font-size: 1.1rem; margin-bottom: 1em; }

.episode-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: .8em;
}
.ep-card {
  background: var(--surface);
  border: 1px solid #2a2a4a;
  border-radius: 6px;
  padding: .9em 1em;
  transition: border-color .15s, background .15s;
}
.ep-card:hover { border-color: var(--accent-blue); background: #0e1228; text-decoration: none; }
.ep-card .ep-num { font-family: monospace; font-size: .75rem; color: var(--accent-blue); display: block; margin-bottom: .2em; }
.ep-card .ep-name { font-size: .88rem; color: var(--text); line-height: 1.35; }

/* ===== THEOREM INDEX ===== */
.theorem-table { width: 100%; border-collapse: collapse; margin-top: 1em; font-size: .88rem; }
.theorem-table th {
  text-align: left;
  padding: .5em .8em;
  border-bottom: 2px solid #2a2a4a;
  color: var(--accent-blue);
  font-size: .75rem;
  text-transform: uppercase;
  letter-spacing: .06em;
}
.theorem-table td {
  padding: .45em .8em;
  border-bottom: 1px solid #1a1a3a;
  vertical-align: top;
}
.theorem-table tr:hover td { background: #0e0e22; }

/* ===== DOMAIN FILTERS ===== */
.filter-bar { display: flex; gap: .5em; flex-wrap: wrap; margin-bottom: 1.2em; }
.filter-btn {
  padding: .25em .75em;
  border: 1px solid #3a3a6a;
  border-radius: 4px;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  font-size: .8rem;
  font-family: inherit;
  transition: all .15s;
}
.filter-btn:hover, .filter-btn.active { background: var(--accent-blue); border-color: var(--accent-blue); color: #0d0d1a; }

/* ===== EPISODE REF INLINE ===== */
.episode-ref-link {
  display: inline-block;
  background: #0a1525;
  border: 1px solid #1a3a55;
  border-radius: 3px;
  padding: .05em .4em;
  font-size: .88em;
  color: var(--accent-blue);
}
.episode-ref-placeholder {
  color: var(--text-muted);
  font-style: italic;
}

/* ===== GENERAL PAGE ===== */
.page-content { max-width: 760px; }
.page-content h1 { margin-top: 0; }

/* ===== CONTENT TABLES ===== */
.episode-content table,
.page-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5em 0;
  font-size: .9rem;
  line-height: 1.5;
}

.episode-content thead,
.page-content thead {
  background: #151530;
  border-bottom: 2px solid var(--accent-blue);
}

.episode-content th,
.page-content th {
  padding: .5em .9em;
  text-align: left;
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--accent-blue);
  white-space: nowrap;
}

.episode-content td,
.page-content td {
  padding: .45em .9em;
  border-bottom: 1px solid #1e1e3a;
  vertical-align: top;
}

.episode-content tbody tr:nth-child(even),
.page-content tbody tr:nth-child(even) {
  background: #0e0e22;
}

.episode-content tbody tr:hover td,
.page-content tbody tr:hover td {
  background: #161628;
}

/* ===== FOOTER ===== */
.site-footer {
  margin-top: 4em;
  padding-top: 1.5em;
  border-top: 1px solid #1a1a3a;
  font-size: .8rem;
  color: var(--text-muted);
}
.footer-content { display: flex; gap: 1em; flex-wrap: wrap; align-items: center; }
.footer-sep { opacity: .5; }
.footer-avatar-link { flex-shrink: 0; }
.footer-avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid #2a2a4a;
  transition: border-color .2s;
}
.footer-avatar:hover { border-color: var(--accent-blue); }
.footer-text { display: flex; gap: .8em; flex-wrap: wrap; align-items: center; }

/* ===== KATEX DISPLAY ===== */
.katex-display { overflow-x: auto; padding: .5em 0; }
.math-display { display: block; overflow-x: auto; padding: .6em 0; text-align: center; }
.math-inline { display: inline; }

/* ===== RESPONSIVE ===== */
/* Hide right TOC when not enough horizontal space */
@media (max-width: 1100px) {
  .ep-toc-aside { display: none; }
}

@media (max-width: 768px) {
  .layout-wrapper { flex-direction: column; }
  .sidebar {
    width: 100%;
    min-width: unset;
    height: auto;
    position: static;
    border-right: none;
    border-bottom: 1px solid #2a2a4a;
  }
  .main-content { padding: 1.5em 1.2em 3em; }
  .ep-nav { flex-direction: column; }
  .ep-nav-next { margin-left: 0; text-align: left; }
}

/* ===== XHS VIDEO CARDS ===== */
.xhs-section {
  margin: 1.6em 0 2em;
  padding: 1.2em 1.4em;
  background: #0f0f20;
  border: 1px solid #2a1a2a;
  border-left: 3px solid #ff2442;
  border-radius: 6px;
}
.xhs-section-header {
  display: flex;
  align-items: center;
  gap: .6em;
  margin-bottom: 1em;
}
.xhs-logo-badge {
  background: #ff2442;
  color: #fff;
  font-size: .7rem;
  font-weight: 700;
  padding: .2em .55em;
  border-radius: 3px;
  letter-spacing: .02em;
}
.xhs-section-title {
  font-size: .85rem;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .05em;
}
.xhs-cards { display: flex; flex-direction: column; gap: .65em; }
.xhs-card {
  display: block;
  text-decoration: none;
  border: 1px solid #2a1a2a;
  border-radius: 5px;
  background: #141426;
  transition: background .15s, border-color .15s;
}
.xhs-card:hover { background: #1c1c38; border-color: #ff2442; text-decoration: none; }
.xhs-card-inner {
  display: flex;
  align-items: center;
  gap: .9em;
  padding: .7em 1em;
}
.xhs-card-icon {
  width: 2em; height: 2em;
  background: #ff2442;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: .65rem; color: #fff;
  flex-shrink: 0;
}
.xhs-card-text { flex: 1; min-width: 0; }
.xhs-card-title {
  font-size: .9rem;
  color: var(--text-primary);
  font-weight: 500;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.xhs-card-sub { font-size: .72rem; color: var(--text-muted); margin-top: .15em; }
.xhs-card-arrow { color: #ff2442; font-size: 1rem; flex-shrink: 0; }