/* ═══════════════════════════════════════════════════════════════════
   Computational Imaging — Course Stylesheet
   ═══════════════════════════════════════════════════════════════════ */

/* ── Web Fonts ───────────────────────────────────────────────────── */
@import url('https://fonts.googleapis.com/css2?family=Source+Serif+4:ital,opsz,wght@0,8..60,300..900;1,8..60,300..900&family=Inter:wght@300;400;500;600&family=JetBrains+Mono:ital,wght@0,400;0,500;1,400&display=swap');

/* ── Design Tokens ───────────────────────────────────────────────── */
:root {
  /* Warm ivory page — the blue accent pops cleanly against this */
  --ci-paper:         #f6f4ef;
  --ci-surface:       rgba(253, 252, 249, 0.97);
  --ci-surface-soft:  rgba(248, 247, 243, 0.93);
  --ci-ink:           #141920;
  --ci-muted:         #52606e;
  --ci-muted-light:   #93a0ad;

  /* Deep sapphire — the signature academic blue */
  --ci-accent:        #1c3f7a;
  --ci-accent-hover:  #14305f;
  --ci-accent-soft:   rgba(28, 63, 122, 0.09);
  --ci-accent-softer: rgba(28, 63, 122, 0.05);

  /* Admonition palette */
  --ci-note-ink:    #1d4ed8;
  --ci-note-bg:     rgba(37,  99, 235, 0.07);
  --ci-note-border: rgba(37,  99, 235, 0.28);
  --ci-tip-ink:     #166534;
  --ci-tip-bg:      rgba(22, 163,  74, 0.07);
  --ci-tip-border:  rgba(22, 163,  74, 0.26);
  --ci-warn-ink:    #92400e;
  --ci-warn-bg:     rgba(180,  83,   9, 0.07);
  --ci-warn-border: rgba(180,  83,   9, 0.24);
  --ci-imp-ink:     #881337;
  --ci-imp-bg:      rgba(136,  19,  55, 0.07);
  --ci-imp-border:  rgba(136,  19,  55, 0.22);

  /* Structure */
  --ci-line:        rgba(20, 25, 32, 0.09);
  --ci-line-strong: rgba(20, 25, 32, 0.17);
  --ci-shadow-sm:   0 2px 8px rgba(20, 25, 32, 0.06);
  --ci-shadow:      0 10px 36px rgba(20, 25, 32, 0.09);
  --ci-shadow-lg:   0 24px 60px rgba(20, 25, 32, 0.13);
  --ci-r:           20px;
  --ci-r-sm:        12px;
  --ci-r-xs:        7px;

  /* Typography stacks */
  --font-serif:   'Source Serif 4', 'Palatino Linotype', Georgia, serif;
  --font-display: 'Palatino Linotype', 'Book Antiqua', Palatino, Georgia, serif;
  --font-ui:      'Inter', 'Helvetica Neue', Arial, sans-serif;
  --font-mono:    'JetBrains Mono', 'Fira Code', 'Cascadia Code', Consolas, monospace;

  /* ── Override PyData Sphinx theme primary color ────────────────── */
  --pst-color-primary:      var(--ci-accent);
  --pst-color-primary-text: #fff;
  --pst-color-link:         var(--ci-accent);
  --pst-color-link-hover:   var(--ci-accent-hover);
}

/* ── Base ────────────────────────────────────────────────────────── */
html { scroll-behavior: smooth; }

::selection {
  background: rgba(28, 63, 122, 0.14);
  color: var(--ci-accent);
}

body {
  color: var(--ci-ink);
  /* Cool-blue whisper in the top-left corner; warm ivory fills the rest */
  background:
    radial-gradient(ellipse 55% 45% at 0% 0%,
      rgba(28, 63, 122, 0.07) 0%, transparent 65%),
    radial-gradient(ellipse 35% 30% at 100% 5%,
      rgba(60, 100, 180, 0.04) 0%, transparent 55%),
    linear-gradient(172deg, #faf9f6 0%, var(--ci-paper) 100%);
  background-attachment: fixed;
}

/* ── Layout ──────────────────────────────────────────────────────── */
.bd-page-width                              { max-width: 98rem; }
.bd-container .bd-content .bd-article-container { max-width: 58rem; }
.bd-main .bd-content .bd-article-container      { padding-top: 2rem; }

/* ── Topbar ──────────────────────────────────────────────────────── */
.bd-header {
  background: rgba(252, 251, 248, 0.94);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--ci-line);
  box-shadow: 0 1px 12px rgba(20, 25, 32, 0.07);
}

.bd-header .navbar-brand,
.bd-header .navbar-nav li a {
  font-family: var(--font-ui);
  font-weight: 500;
  font-size: 0.9rem;
  letter-spacing: 0.01em;
  transition: color 0.18s;
}

/* ── Sidebars ────────────────────────────────────────────────────── */
.bd-sidebar-primary,
.bd-sidebar-secondary {
  background: var(--ci-surface-soft);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.bd-sidebar-primary  { border-right: 1px solid var(--ci-line); }
.bd-sidebar-secondary { border-left:  1px solid var(--ci-line); }

/* ── Article card ────────────────────────────────────────────────── */
.bd-article-container {
  background: var(--ci-surface);
  border: 1px solid rgba(240, 237, 230, 0.9);
  border-radius: var(--ci-r);
  box-shadow:
    0 0 0 1px rgba(255, 255, 255, 0.55),
    var(--ci-shadow);
  padding: 2.25rem 2.75rem 3.5rem;
  margin-bottom: 2.5rem;
}

.bd-header-article,
.bd-header-article .header-article__inner,
.bd-header-article .header-article-items,
.bd-header-article .header-article-items__start,
.bd-header-article .header-article-items__end,
.bd-header-article .header-article-item {
  background: transparent !important;
  box-shadow: none !important;
  border: 0 !important;
}

.bd-header-article {
  margin: -0.25rem -0.25rem 1.25rem;
  padding: 0 0.25rem 0.85rem;
  border-bottom: 1px solid var(--ci-line) !important;
}

.bd-header-article .btn {
  background: rgba(255, 255, 255, 0.50);
  border-color: var(--ci-line);
  border-radius: var(--ci-r-xs);
  font-family: var(--font-ui);
  font-size: 0.8rem;
  transition: background 0.18s, border-color 0.18s;
}

.bd-header-article .btn:hover { background: rgba(255, 255, 255, 0.78); }

/* ── Typography ──────────────────────────────────────────────────── */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  /* Deep slate with a slight blue cast */
  color: #0d1a2f;
  letter-spacing: -0.02em;
}

h1 {
  font-size: clamp(2.1rem, 3vw, 3rem);
  font-weight: 700;
  line-height: 1.08;
  margin-bottom: 1.3rem;
}

h2 {
  font-size: clamp(1.5rem, 2vw, 1.9rem);
  font-weight: 700;
  margin-top: 3rem;
  padding-top: 0.5rem;
  border-top: 1px solid var(--ci-line);
}

h3 {
  font-size: clamp(1.2rem, 1.5vw, 1.45rem);
  font-weight: 600;
  margin-top: 2rem;
}

h4 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-top: 1.5rem;
}

p, li {
  font-family: var(--font-serif);
  font-size: 1.035rem;
  line-height: 1.82;
  color: var(--ci-ink);
}

p + p { margin-top: 0.8em; }

strong {
  font-weight: 650;
  color: #102a52;
}

em {
  font-style: italic;
  color: #243447;
}

a {
  color: var(--ci-accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.16s, border-color 0.16s;
}

a:hover {
  color: var(--ci-accent-hover);
  border-bottom-color: rgba(28, 63, 122, 0.28);
}

/* ── Sidebar navigation ──────────────────────────────────────────── */
nav.bd-links p.caption {
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ci-muted);
}

nav.bd-links li > a {
  font-family: var(--font-ui);
  font-size: 0.875rem;
  border-radius: var(--ci-r-xs);
  transition: color 0.16s;
}

/* Active item in left sidebar */
nav.bd-links .current > a {
  background-color: var(--ci-accent-softer) !important;
  box-shadow: inset max(3px, .1875rem, .12em) 0 0 var(--ci-accent) !important;
  color: var(--ci-accent) !important;
  font-weight: 600;
}

nav.bd-links .current > a:focus-visible {
  box-shadow:
    inset max(3px, .1875rem, .12em) 0 0 var(--ci-accent),
    0 0 0 .1875rem var(--ci-accent) !important;
}

/* Active item in right TOC */
.toc-entry a.nav-link.active {
  background-color: transparent !important;
  box-shadow: inset max(3px, .1875rem, .12em) 0 0 var(--ci-accent) !important;
  color: var(--ci-accent) !important;
  font-weight: 600;
}

.toc-entry a.nav-link.active:focus-visible {
  box-shadow:
    inset max(3px, .1875rem, .12em) 0 0 var(--ci-accent),
    0 0 0 .1875rem var(--ci-accent) !important;
}

.toc-entry a.nav-link { font-family: var(--font-ui); }

/* ── Admonitions — recolor without touching icons ────────────────── */
/* The PyData theme renders the icon via ::after (Font Awesome).
   We only override border, background, and title colors here.       */

/* note */
.admonition.note, div.note {
  border-color: var(--ci-note-border);
  background-color: var(--ci-note-bg);
}
.admonition.note > .admonition-title,
div.note > .admonition-title {
  background-color: rgba(37, 99, 235, 0.10);
  color: var(--ci-note-ink);
}
.admonition.note > .admonition-title::after,
div.note > .admonition-title::after {
  color: var(--ci-note-ink);
}

/* tip / hint */
.admonition.tip, div.tip,
.admonition.hint, div.hint {
  border-color: var(--ci-tip-border);
  background-color: var(--ci-tip-bg);
}
.admonition.tip > .admonition-title,
div.tip > .admonition-title,
.admonition.hint > .admonition-title,
div.hint > .admonition-title {
  background-color: rgba(22, 163, 74, 0.10);
  color: var(--ci-tip-ink);
}
.admonition.tip > .admonition-title::after,
div.tip > .admonition-title::after,
.admonition.hint > .admonition-title::after,
div.hint > .admonition-title::after {
  color: var(--ci-tip-ink);
}

/* warning / caution / attention */
.admonition.warning, div.warning,
.admonition.caution, div.caution,
.admonition.attention, div.attention {
  border-color: var(--ci-warn-border);
  background-color: var(--ci-warn-bg);
}
.admonition.warning > .admonition-title,
div.warning > .admonition-title,
.admonition.caution > .admonition-title,
div.caution > .admonition-title,
.admonition.attention > .admonition-title,
div.attention > .admonition-title {
  background-color: rgba(180, 83, 9, 0.10);
  color: var(--ci-warn-ink);
}
.admonition.warning > .admonition-title::after,
div.warning > .admonition-title::after,
.admonition.caution > .admonition-title::after,
div.caution > .admonition-title::after,
.admonition.attention > .admonition-title::after,
div.attention > .admonition-title::after {
  color: var(--ci-warn-ink);
}

/* important */
.admonition.important, div.important {
  border-color: var(--ci-imp-border);
  background-color: var(--ci-imp-bg);
}
.admonition.important > .admonition-title,
div.important > .admonition-title {
  background-color: rgba(136, 19, 55, 0.10);
  color: var(--ci-imp-ink);
}
.admonition.important > .admonition-title::after,
div.important > .admonition-title::after {
  color: var(--ci-imp-ink);
}

/* numerical example */
.admonition.numerical-example, div.numerical-example {
  border-color: rgba(28, 63, 122, 0.28);
  border-left-width: 5px;
  background:
    linear-gradient(180deg, rgba(28, 63, 122, 0.07) 0%, rgba(252, 251, 248, 0.95) 100%);
  box-shadow:
    0 0 0 1px rgba(255, 255, 255, 0.45),
    0 12px 26px rgba(20, 25, 32, 0.06) !important;
}
.admonition.numerical-example > .admonition-title,
div.numerical-example > .admonition-title {
  background:
    linear-gradient(90deg, rgba(28, 63, 122, 0.12) 0%, rgba(28, 63, 122, 0.06) 100%);
  color: var(--ci-accent);
  font-family: var(--font-ui);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.admonition.numerical-example > .admonition-title::after,
div.numerical-example > .admonition-title::after {
  color: var(--ci-accent);
}
.admonition.numerical-example p,
div.numerical-example p,
.admonition.numerical-example li,
div.numerical-example li {
  font-size: 0.99rem;
}

/* Shared shape overrides */
.admonition, div.admonition {
  border-radius: var(--ci-r-sm);
  border-left-width: 3px;
  box-shadow: var(--ci-shadow-sm) !important;
}

.admonition p, div.admonition p {
  font-family: var(--font-serif);
  font-size: 0.98rem;
}

/* ── Theorem / Proof Environments ───────────────────────────────── */
/* Override sphinx-proof's bright default palette so theorem-like
   blocks feel like part of the same book design language. */

:root {
  --ci-proof-surface: rgba(252, 251, 248, 0.9);
  --ci-proof-surface-strong: rgba(247, 245, 239, 0.95);
  --ci-proof-border: rgba(28, 63, 122, 0.2);
  --ci-proof-rule: rgba(28, 63, 122, 0.34);
  --ci-proof-title: #16386d;
  --ci-proof-muted: #5f6c7a;
  --ci-proof-shadow: 0 10px 24px rgba(20, 25, 32, 0.05);

  --ci-theorem-bg: rgba(28, 63, 122, 0.045);
  --ci-theorem-title-bg: rgba(28, 63, 122, 0.075);
  --ci-lemma-bg: rgba(22, 101, 52, 0.045);
  --ci-lemma-title-bg: rgba(22, 101, 52, 0.075);
  --ci-definition-bg: rgba(180, 83, 9, 0.04);
  --ci-definition-title-bg: rgba(180, 83, 9, 0.075);
  --ci-remark-bg: rgba(82, 96, 110, 0.05);
  --ci-remark-title-bg: rgba(82, 96, 110, 0.085);
  --ci-example-bg: rgba(136, 19, 55, 0.04);
  --ci-example-title-bg: rgba(136, 19, 55, 0.07);
}

div.proof.admonition {
  border: 1px solid var(--ci-proof-border) !important;
  border-left: 3px solid var(--ci-proof-rule) !important;
  border-radius: 14px !important;
  background: var(--ci-proof-surface) !important;
  box-shadow: var(--ci-proof-shadow) !important;
  overflow: hidden;
  margin: 1.35rem 0 1.5rem;
}

div.proof.admonition > p.admonition-title {
  display: flex;
  align-items: baseline;
  gap: 0.45rem;
  margin: 0 !important;
  padding: 0.72rem 1rem 0.7rem 1rem !important;
  background: var(--ci-proof-surface-strong) !important;
  border-bottom: 1px solid rgba(20, 25, 32, 0.07);
  font-family: var(--font-ui);
  font-size: 0.82rem;
  font-weight: 600 !important;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ci-proof-title) !important;
}

div.proof.admonition > p.admonition-title::before {
  content: none !important;
}

div.proof.admonition > p.admonition-title::after {
  content: none !important;
  display: none !important;
  color: var(--ci-proof-title) !important;
}

div.proof.admonition > p.admonition-title > span.caption-number {
  font-weight: 700 !important;
  color: var(--ci-proof-title) !important;
}

div.proof.admonition > section.theorem-content,
div.proof.admonition > .admonition-content,
div.proof.admonition > p:not(.admonition-title),
div.proof.admonition > div.math,
div.proof.admonition > div.section {
  padding-left: 1rem;
  padding-right: 1rem;
}

div.proof.admonition > section.theorem-content {
  padding-top: 0.95rem;
  padding-bottom: 0.95rem;
}

div.proof.admonition > section.theorem-content > :first-child,
div.proof.admonition > :not(.admonition-title):first-of-type {
  margin-top: 0;
}

div.proof.admonition p,
div.proof.admonition li {
  font-size: 1rem;
  line-height: 1.78;
}

div.proof.admonition div.math.notranslate {
  margin: 1rem 1rem;
}

div.proof.admonition#proof,
div.proof.admonition[id="proof"] {
  background: rgba(250, 249, 245, 0.98) !important;
  border-left-color: rgba(82, 96, 110, 0.38) !important;
}

div.proof.admonition#proof > p.admonition-title,
div.proof.admonition[id="proof"] > p.admonition-title {
  background: rgba(82, 96, 110, 0.06) !important;
  color: #394656 !important;
}

div.proof.admonition#proof > p.admonition-title::after,
div.proof.admonition[id="proof"] > p.admonition-title::after,
div.proof.admonition#proof > p.admonition-title > span.caption-number,
div.proof.admonition[id="proof"] > p.admonition-title > span.caption-number {
  color: #394656 !important;
}

div.theorem.proof.admonition {
  background: linear-gradient(180deg, var(--ci-theorem-bg) 0%, var(--ci-proof-surface) 100%) !important;
}

div.theorem.proof.admonition > p.admonition-title {
  background: var(--ci-theorem-title-bg) !important;
}

div.lemma.proof.admonition,
div.proposition.proof.admonition,
div.corollary.proof.admonition {
  background: linear-gradient(180deg, var(--ci-lemma-bg) 0%, var(--ci-proof-surface) 100%) !important;
}

div.lemma.proof.admonition > p.admonition-title,
div.proposition.proof.admonition > p.admonition-title,
div.corollary.proof.admonition > p.admonition-title {
  background: var(--ci-lemma-title-bg) !important;
}

div.definition.proof.admonition,
div.assumption.proof.admonition,
div.notation.proof.admonition {
  background: linear-gradient(180deg, var(--ci-definition-bg) 0%, var(--ci-proof-surface) 100%) !important;
}

div.definition.proof.admonition > p.admonition-title,
div.assumption.proof.admonition > p.admonition-title,
div.notation.proof.admonition > p.admonition-title {
  background: var(--ci-definition-title-bg) !important;
}

div.remark.proof.admonition,
div.observation.proof.admonition {
  background: linear-gradient(180deg, var(--ci-remark-bg) 0%, var(--ci-proof-surface) 100%) !important;
}

div.remark.proof.admonition > p.admonition-title,
div.observation.proof.admonition > p.admonition-title {
  background: var(--ci-remark-title-bg) !important;
}

div.example.proof.admonition {
  background: linear-gradient(180deg, var(--ci-example-bg) 0%, var(--ci-proof-surface) 100%) !important;
}

div.example.proof.admonition > p.admonition-title {
  background: var(--ci-example-title-bg) !important;
}

/* ── Code ────────────────────────────────────────────────────────── */
code, kbd, samp, tt {
  font-family: var(--font-mono);
  font-size: 0.875em;
  /* Warm parchment inline code — contrasts with the cool body */
  background: rgba(100, 60, 20, 0.06);
  border: 1px solid rgba(100, 60, 20, 0.10);
  border-radius: 5px;
  padding: 0.1em 0.38em;
  color: var(--ci-accent);
}

div.highlight, pre {
  font-family: var(--font-mono);
  font-size: 0.865rem;
  line-height: 1.65;
  border: 1px solid rgba(20, 25, 32, 0.09);
  border-radius: var(--ci-r-sm);
}

pre {
  /* Warm cream code blocks — intentional contrast against the cool sidebars */
  background: #f5f1e8;
  padding: 1.1rem 1.3rem;
}

.copybtn {
  border-radius: var(--ci-r-xs) !important;
  background: rgba(255, 255, 255, 0.55) !important;
  border: 1px solid var(--ci-line) !important;
  transition: background 0.18s !important;
}
.copybtn:hover { background: rgba(255, 255, 255, 0.85) !important; }

/* ── Jupyter notebook cells ──────────────────────────────────────── */
.cell { margin: 1.2rem 0; }

.cell_input {
  position: relative;
  border: 1px solid rgba(20, 25, 32, 0.09);
  border-radius: var(--ci-r-sm);
  background: #f5f1e8;
}

.cell_input .highlight {
  border: none;
  border-radius: var(--ci-r-sm);
  background: transparent;
  margin: 0;
}

.cell_input .highlight pre {
  background: transparent;
  border: none;
  border-radius: 0;
  padding: 0.95rem 1.1rem;
}

/* Subtle "In" label */
.cell_input::before {
  content: 'In';
  position: absolute;
  top: 0.55rem;
  right: 0.65rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 500;
  color: var(--ci-muted-light);
  letter-spacing: 0.04em;
  pointer-events: none;
}

.cell_output {
  border: 1px solid var(--ci-line);
  border-top: none;
  border-radius: 0 0 var(--ci-r-sm) var(--ci-r-sm);
  background: rgba(252, 251, 249, 0.75);
  margin-top: -1px;
}

.cell_output pre {
  background: transparent;
  border: none;
  border-radius: 0;
  padding: 0.85rem 1.1rem;
  color: #2a3040;
  font-size: 0.845rem;
}

.cell_output img {
  border-radius: var(--ci-r-xs);
  max-width: 100%;
  display: block;
  margin: 0.5rem auto;
}

/* ── Math — tame the scrollbar ───────────────────────────────────── */
.math mjx-container {
  padding-bottom: 0 !important;
  scrollbar-width: thin;
  scrollbar-color: rgba(20, 25, 32, 0.12) transparent;
}

.math mjx-container::-webkit-scrollbar       { height: 3px; }
.math mjx-container::-webkit-scrollbar-track  { background: transparent; }
.math mjx-container::-webkit-scrollbar-thumb  {
  background: rgba(20, 25, 32, 0.15);
  border-radius: 3px;
}

div.math.notranslate {
  margin: 1.4rem 0;
  overflow-x: auto;
  overflow-y: hidden;
}

/* ── Tables ──────────────────────────────────────────────────────── */
table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  border-radius: var(--ci-r-sm);
  overflow: hidden;
  border: 1px solid var(--ci-line);
  box-shadow: var(--ci-shadow-sm);
  margin: 1.5rem 0;
  font-family: var(--font-ui);
  font-size: 0.9rem;
}

table thead tr { background: rgba(28, 63, 122, 0.05); }

table thead th {
  font-weight: 600;
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ci-muted);
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--ci-line-strong);
}

table tbody tr:nth-child(even) { background: rgba(20, 25, 32, 0.022); }

table tbody td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid var(--ci-line);
  vertical-align: top;
}

table tbody tr:last-child td { border-bottom: none; }

/* ── Blockquotes ─────────────────────────────────────────────────── */
blockquote {
  border-left: 3px solid var(--ci-accent);
  background: rgba(28, 63, 122, 0.04);
  border-radius: 0 var(--ci-r-sm) var(--ci-r-sm) 0;
  padding: 0.75rem 1.2rem 0.75rem 1.3rem;
  margin: 1.2rem 0;
}

blockquote p {
  font-style: italic;
  color: var(--ci-muted);
  margin: 0;
}

/* ── Prev / Next navigation ──────────────────────────────────────── */
.prev-next-area a {
  border: 1px solid var(--ci-line) !important;
  border-radius: var(--ci-r-sm);
  background: rgba(252, 251, 249, 0.88) !important;
  box-shadow: var(--ci-shadow-sm);
  transition: background 0.18s, box-shadow 0.18s, border-color 0.18s;
  max-width: 48%;
}

.prev-next-area a:hover {
  background: var(--ci-surface) !important;
  border-color: rgba(28, 63, 122, 0.20) !important;
  box-shadow: 0 4px 18px rgba(20, 25, 32, 0.10);
}

.prev-next-area a p.prev-next-subtitle {
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--ci-muted);
}

.prev-next-area a p.prev-next-title {
  font-family: var(--font-ui);
  font-size: 0.9rem !important;
  font-weight: 500;
  color: var(--ci-ink) !important;
}

/* ── Footer ──────────────────────────────────────────────────────── */
.bd-footer-content {
  font-family: var(--font-ui);
  font-size: 0.82rem;
  color: var(--ci-muted);
  border-top: 1px solid var(--ci-line);
}

/* ── Citation tooltip ────────────────────────────────────────────── */
#ci-cite-tooltip {
  position: fixed;
  z-index: 9999;
  max-width: 360px;
  background: var(--ci-surface);
  border: 1px solid var(--ci-line-strong);
  border-radius: var(--ci-r-sm);
  box-shadow: var(--ci-shadow-lg);
  padding: 0.8rem 1.05rem;
  pointer-events: none;
  opacity: 0;
  transform: translateY(4px);
  transition: opacity 0.18s ease, transform 0.18s ease;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

#ci-cite-tooltip.visible {
  opacity: 1;
  transform: translateY(0);
}

#ci-cite-tooltip p {
  font-family: var(--font-ui);
  font-size: 0.82rem;
  line-height: 1.55;
  color: var(--ci-ink);
  margin: 0;
}

/* Citation links in text */
span[id] > a.reference.internal,
cite > a.reference.internal {
  font-weight: 500;
  border-bottom: 1px dashed rgba(28, 63, 122, 0.32);
  padding: 0 0.05em;
  cursor: help;
  transition: background 0.14s;
}

span[id] > a.reference.internal:hover,
cite > a.reference.internal:hover {
  background: var(--ci-accent-soft);
  border-radius: 3px;
  border-bottom-color: transparent;
}

/* ── Responsive ──────────────────────────────────────────────────── */
@media (max-width: 991.98px) {
  .bd-article-container {
    border-radius: var(--ci-r-sm);
    padding: 1.5rem 1.3rem 2.25rem;
  }
}

@media (max-width: 575.98px) {
  .bd-article-container {
    border-radius: 12px;
    padding: 1.1rem 1rem 1.8rem;
  }
  h1 { font-size: 1.85rem; }
}

/* ── Theorems and proofs ────────────────────────────────────────── */
.proof,
.prf-theorem,
.prf-lemma,
.prf-proposition,
.prf-corollary,
.prf-definition {
  border-radius: var(--ci-r-sm);
  border: 1px solid var(--ci-line);
  box-shadow: var(--ci-shadow-sm);
  margin: 1.4rem 0;
  overflow: hidden;
}

.proof .admonition-title,
.prf-theorem .admonition-title,
.prf-lemma .admonition-title,
.prf-proposition .admonition-title,
.prf-corollary .admonition-title,
.prf-definition .admonition-title {
  font-family: var(--font-ui);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin: 0;
  padding: 0.75rem 1rem;
}

.prf-theorem,
.prf-lemma,
.prf-proposition,
.prf-corollary,
.prf-definition {
  background: rgba(28, 63, 122, 0.045);
  border-color: rgba(28, 63, 122, 0.18);
}

.prf-theorem .admonition-title,
.prf-lemma .admonition-title,
.prf-proposition .admonition-title,
.prf-corollary .admonition-title,
.prf-definition .admonition-title {
  color: var(--ci-accent);
  background: rgba(28, 63, 122, 0.09);
}

.proof {
  background: rgba(22, 163, 74, 0.045);
  border-color: rgba(22, 163, 74, 0.18);
}

.proof .admonition-title {
  color: var(--ci-tip-ink);
  background: rgba(22, 163, 74, 0.09);
}
.course-editions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem 0.8rem;
  margin-bottom: 1rem;
}

.course-editions strong {
  flex-basis: 100%;
  font-size: 0.85rem;
}

.course-editions a[aria-current="true"] {
  font-weight: 700;
  text-decoration: underline;
  text-underline-offset: 0.2em;
}