/* ============================================================
   reader.css — Independent reader design system
   Warm "scriptorium" aesthetic, coherent with the site's
   parchment / oxblood / olive language. 100% original rules,
   no @import of vars.css, no dependency on the old reader.
   ============================================================ */

/* ---------- Base ---------- */

:root {
  /* typography */
  --rdr-font-body:  'Noto Serif SC', 'Songti SC', 'Source Han Serif SC', Georgia, serif;
  --rdr-font-ui:    'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
  --rdr-font-latin: 'EB Garamond', 'Noto Serif SC', Georgia, serif;
  --rdr-font-mono:  'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;

  /* geometry */
  --rdr-topbar-h:   54px;
  --rdr-sidebar-w:  300px;
  --rdr-font-size:  18px;   /* overridden inline from localStorage */
  --rdr-measure:    38em;   /* overridden via html[data-measure] */

  --rdr-radius:     10px;
  --rdr-radius-sm:  7px;
  --rdr-motion:     cubic-bezier(0.22, 0.61, 0.36, 1);
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; color-scheme: light; }

html,
body { height: 100%; }

body {
  overflow: hidden;               /* #rdr-main scrolls, not body */
  font-family: var(--rdr-font-body);
  font-size: var(--rdr-font-size);
  line-height: 1.85;
  color: var(--rdr-fg);
  background-color: var(--rdr-bg);
  background-image:
    radial-gradient(circle at 16% 10%, var(--rdr-bg-grain) 0, transparent 42%),
    radial-gradient(circle at 84% 82%, var(--rdr-bg-grain) 0, transparent 46%);
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background-color 0.25s ease, color 0.25s ease;
}

/* ---------- Theme palettes ---------- */

html[data-theme="light"] {
  color-scheme: light;
  --rdr-bg:           #FAF6EC;
  --rdr-bg-grain:     #F3ECDB;
  --rdr-surface:      #F4EEDF;
  --rdr-surface-2:    #EFE7D4;
  --rdr-fg:           #241B11;
  --rdr-muted:        #6A5C49;
  --rdr-faint:        #8C7B61;
  --rdr-accent:       #8A3517;
  --rdr-accent-ink:   #732A11;
  --rdr-accent-soft:  rgba(138, 53, 23, 0.10);
  --rdr-olive:        #4A6741;
  --rdr-olive-ink:    #3A5133;
  --rdr-olive-soft:   rgba(74, 103, 65, 0.10);
  --rdr-border:       #E2D8C3;
  --rdr-rule:         #D9CDB4;
  --rdr-quote-bg:     #F1E8D3;
  --rdr-mark:         rgba(138, 53, 23, 0.12);
  --rdr-shadow:       rgba(48, 33, 16, 0.13);
  --rdr-shadow-deep:  rgba(48, 33, 16, 0.24);
  --rdr-scrim:        rgba(36, 27, 17, 0.38);
  --rdr-on-accent:    #FBF6EA;
  --rdr-topbar-bg:    rgba(250, 246, 236, 0.88);
  --rdr-error-bg:     #FBEAE3;
  --rdr-error-fg:     #8A3517;
}

html[data-theme="sepia"] {
  color-scheme: light;
  --rdr-bg:           #EFDFBF;
  --rdr-bg-grain:     #E5D0A5;
  --rdr-surface:      #E8D5AE;
  --rdr-surface-2:    #DCC69A;
  --rdr-fg:           #3A2A1A;
  --rdr-muted:        #6B5236;
  --rdr-faint:        #7E6A4E;
  --rdr-accent:       #9A3F1C;
  --rdr-accent-ink:   #7C3113;
  --rdr-accent-soft:  rgba(154, 63, 28, 0.12);
  --rdr-olive:        #5B6B3E;
  --rdr-olive-ink:    #48562F;
  --rdr-olive-soft:   rgba(91, 107, 62, 0.12);
  --rdr-border:       #D8BE8F;
  --rdr-rule:         #CCAE78;
  --rdr-quote-bg:     #E6CFA2;
  --rdr-mark:         rgba(154, 63, 28, 0.14);
  --rdr-shadow:       rgba(58, 42, 26, 0.18);
  --rdr-shadow-deep:  rgba(58, 42, 26, 0.32);
  --rdr-scrim:        rgba(46, 32, 18, 0.46);
  --rdr-on-accent:    #F7EFE0;
  --rdr-topbar-bg:    rgba(239, 223, 191, 0.90);
  --rdr-error-bg:     #F0D8C6;
  --rdr-error-fg:     #8A3517;
}

html[data-theme="dark"] {
  color-scheme: dark;
  --rdr-bg:           #1C1A16;
  --rdr-bg-grain:     #26231C;
  --rdr-surface:      #26221C;
  --rdr-surface-2:    #2F2A22;
  --rdr-fg:           #E9DFCB;
  --rdr-muted:        #B3A78E;
  --rdr-faint:        #8F8672;
  --rdr-accent:       #D07A55;
  --rdr-accent-ink:   #E8A98B;
  --rdr-accent-soft:  rgba(208, 122, 85, 0.14);
  --rdr-olive:        #9DB184;
  --rdr-olive-ink:    #B5C69F;
  --rdr-olive-soft:   rgba(157, 177, 132, 0.14);
  --rdr-border:       #3A352B;
  --rdr-rule:         #453E31;
  --rdr-quote-bg:     #27231C;
  --rdr-mark:         rgba(208, 122, 85, 0.14);
  --rdr-shadow:       rgba(0, 0, 0, 0.35);
  --rdr-shadow-deep:  rgba(0, 0, 0, 0.55);
  --rdr-scrim:        rgba(0, 0, 0, 0.55);
  --rdr-on-accent:    #241B11;
  --rdr-topbar-bg:    rgba(28, 26, 22, 0.86);
  --rdr-error-bg:     #3A2620;
  --rdr-error-fg:     #E8A98B;
}

/* ---------- Measure ---------- */

html[data-measure="narrow"]   { --rdr-measure: 30em; }
html[data-measure="standard"] { --rdr-measure: 38em; }
html[data-measure="wide"]     { --rdr-measure: 48em; }

/* ---------- Shared element rules ---------- */

[hidden] { display: none !important; }

a { color: inherit; text-decoration: none; }

::selection { background: var(--rdr-mark); color: var(--rdr-accent-ink); }

:focus-visible {
  outline: 2px solid var(--rdr-accent);
  outline-offset: 2px;
}

button {
  font-family: var(--rdr-font-ui);
  color: inherit;
  background: none;
  border: none;
  cursor: pointer;
}

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

#rdr-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0;                       /* width set by reader.js */
  height: 3px;
  z-index: 60;
  border-radius: 0 2px 2px 0;
  background: linear-gradient(90deg, var(--rdr-accent) 0%, var(--rdr-olive) 100%);
  box-shadow: 0 0 6px var(--rdr-accent-soft);
  transition: width 0.12s linear;
  pointer-events: none;
}

/* ---------- Top bar ---------- */

#rdr-topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--rdr-topbar-h);
  z-index: 40;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 0 12px;
  background: var(--rdr-topbar-bg);
  -webkit-backdrop-filter: blur(12px) saturate(1.2);
  backdrop-filter: blur(12px) saturate(1.2);
  border-bottom: 1px solid var(--rdr-rule);
}

#rdr-topbar button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--rdr-radius-sm);
  color: var(--rdr-fg);
  transition: background-color 0.15s ease, color 0.15s ease;
}

#rdr-topbar button:hover {
  background: var(--rdr-accent-soft);
  color: var(--rdr-accent-ink);
}

#rdr-menu {
  flex: none;
  width: 38px;
  height: 38px;
}

#rdr-title {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  max-width: min(44vw, 560px);
  font-family: var(--rdr-font-latin), var(--rdr-font-body);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  color: var(--rdr-fg);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

#rdr-topnav {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 4px;
  flex: none;
}

#rdr-prev,
#rdr-next {
  padding: 7px 10px;
  gap: 5px;
  font-size: 0.92em;
  font-weight: 500;
  color: var(--rdr-muted);
}

#rdr-prev:hover,
#rdr-next:hover {
  color: var(--rdr-accent-ink);
}

#rdr-courseware {
  display: inline-flex;
  align-items: center;
  padding: 7px 12px;
  margin-left: 4px;
  border: 1px solid var(--rdr-olive);
  border-radius: 999px;
  font-family: var(--rdr-font-ui);
  font-size: 0.86em;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--rdr-olive-ink);
  background: var(--rdr-olive-soft);
  transition: background-color 0.15s ease, color 0.15s ease;
}

#rdr-courseware:hover {
  background: var(--rdr-olive);
  color: var(--rdr-on-accent);
}

#rdr-settings-btn {
  width: 38px;
  height: 38px;
  margin-left: 2px;
}

/* ---------- Settings popover ---------- */

#rdr-settings {
  position: fixed;
  top: calc(var(--rdr-topbar-h) + 10px);
  right: 12px;
  z-index: 45;
  width: 268px;
  padding: 16px 18px;
  background: var(--rdr-surface);
  border: 1px solid var(--rdr-border);
  border-radius: 14px;
  box-shadow: 0 14px 40px var(--rdr-shadow-deep);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px) scale(0.98);
  transform-origin: top right;
  transition: opacity 0.18s ease, transform 0.18s var(--rdr-motion), visibility 0.18s;
}

body.rdr-settings-open #rdr-settings {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.rdr-setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 8px 0;
}

.rdr-setting-row + .rdr-setting-row {
  border-top: 1px dashed var(--rdr-border);
  margin-top: 2px;
}

.rdr-setting-label {
  flex: none;
  font-family: var(--rdr-font-ui);
  font-size: 0.85em;
  letter-spacing: 0.08em;
  color: var(--rdr-muted);
}

.rdr-setting-group {
  display: flex;
  align-items: center;
  gap: 8px;
}

#rdr-font-minus,
#rdr-font-plus {
  width: 34px;
  height: 34px;
  border: 1px solid var(--rdr-border);
  border-radius: var(--rdr-radius-sm);
  background: var(--rdr-bg);
  font-size: 1em;
  font-weight: 600;
  color: var(--rdr-fg);
  transition: border-color 0.15s ease, color 0.15s ease, background-color 0.15s ease;
}

#rdr-font-minus:hover,
#rdr-font-plus:hover {
  border-color: var(--rdr-accent);
  color: var(--rdr-accent-ink);
  background: var(--rdr-accent-soft);
}

#rdr-font-label {
  min-width: 2.4em;
  text-align: center;
  font-family: var(--rdr-font-ui);
  font-size: 0.95em;
  font-weight: 600;
  color: var(--rdr-fg);
}

.rdr-seg {
  display: flex;
  flex: 1;
  max-width: 150px;
  border: 1px solid var(--rdr-border);
  border-radius: 9px;
  overflow: hidden;
  background: var(--rdr-bg);
}

.rdr-seg button {
  flex: 1;
  padding: 7px 0;
  font-size: 0.84em;
  color: var(--rdr-muted);
  transition: background-color 0.15s ease, color 0.15s ease;
  white-space: nowrap;
}

.rdr-seg button + button {
  border-left: 1px solid var(--rdr-border);
}

.rdr-seg button:hover {
  color: var(--rdr-accent-ink);
}

.rdr-seg button.active {
  background: var(--rdr-accent);
  color: var(--rdr-on-accent);
  font-weight: 600;
}

/* Fallback active state keyed off the <html> data attrs (the source of truth),
   so the settings panel always mirrors the applied theme/measure. */
html[data-theme="light"] .rdr-seg button[data-theme="light"],
html[data-theme="sepia"] .rdr-seg button[data-theme="sepia"],
html[data-theme="dark"] .rdr-seg button[data-theme="dark"],
html[data-measure="narrow"] .rdr-seg button[data-measure="narrow"],
html[data-measure="standard"] .rdr-seg button[data-measure="standard"],
html[data-measure="wide"] .rdr-seg button[data-measure="wide"] {
  background: var(--rdr-accent);
  color: var(--rdr-on-accent);
  font-weight: 600;
}

/* ---------- Sidebar drawer ---------- */

#rdr-sidebar {
  position: fixed;
  top: var(--rdr-topbar-h);
  left: 0;
  bottom: 0;
  width: var(--rdr-sidebar-w);
  z-index: 30;
  overflow-y: auto;
  overscroll-behavior: contain;
  background: var(--rdr-surface);
  border-right: 1px solid var(--rdr-border);
  box-shadow: 18px 0 44px var(--rdr-shadow-deep);
  transform: translateX(-105%);
  transition: transform 0.3s var(--rdr-motion);
  scrollbar-width: thin;
  scrollbar-color: var(--rdr-rule) transparent;
}

body.rdr-sidebar-open #rdr-sidebar {
  transform: translateX(0);
}

#rdr-toc {
  list-style: none;
}

#rdr-sidebar::-webkit-scrollbar { width: 8px; }
#rdr-sidebar::-webkit-scrollbar-track { background: transparent; }
#rdr-sidebar::-webkit-scrollbar-thumb {
  background: var(--rdr-rule);
  border-radius: 4px;
  border: 2px solid var(--rdr-surface);
}

/* TOC part headings (sidebar) */
#rdr-sidebar .rdr-part-title {
  position: sticky;
  top: 0;
  z-index: 1;
  padding: 18px 22px 9px;
  font-family: var(--rdr-font-ui);
  font-size: 0.8em;
  font-weight: 600;
  letter-spacing: 0.22em;
  color: var(--rdr-olive-ink);
  background: var(--rdr-surface);
  border-bottom: 1px solid var(--rdr-rule);
}

/* TOC items (sidebar) */
#rdr-sidebar .rdr-toc-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 22px 12px 19px;
  border-left: 3px solid transparent;
  font-family: var(--rdr-font-body);
  font-size: 0.98em;
  line-height: 1.5;
  color: var(--rdr-muted);
  transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

#rdr-sidebar .rdr-toc-item:hover {
  color: var(--rdr-accent-ink);
  background: var(--rdr-accent-soft);
}

#rdr-sidebar .rdr-toc-item.active {
  color: var(--rdr-accent-ink);
  font-weight: 600;
  border-left-color: var(--rdr-accent);
  background: var(--rdr-accent-soft);
}

/* ---------- Scroll container ---------- */

#rdr-main {
  position: fixed;
  top: var(--rdr-topbar-h);
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 10;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
  transition: left 0.3s var(--rdr-motion);
  scrollbar-width: thin;
  scrollbar-color: var(--rdr-rule) transparent;
}

/* Push content right when drawer opens on desktop */
@media (min-width: 821px) {
  body.rdr-sidebar-open #rdr-main {
    left: var(--rdr-sidebar-w);
  }
}

#rdr-main::-webkit-scrollbar { width: 10px; }
#rdr-main::-webkit-scrollbar-track { background: transparent; }
#rdr-main::-webkit-scrollbar-thumb {
  background: var(--rdr-rule);
  border-radius: 6px;
  border: 2px solid var(--rdr-bg);
}

#rdr-content {
  flex: 1 0 auto;
  width: 100%;
  max-width: var(--rdr-measure);
  margin: 0 auto;
  padding: clamp(40px, 8vh, 76px) clamp(20px, 5vw, 40px) 0;
  font-size: var(--rdr-font-size);
  color: var(--rdr-fg);
}

/* ---------- Back to top ---------- */

#rdr-back-top {
  position: fixed;
  right: 22px;
  bottom: 22px;
  z-index: 26;
  width: 44px;
  height: 44px;
  border: 1px solid var(--rdr-border);
  border-radius: 50%;
  background: var(--rdr-surface);
  color: var(--rdr-accent);
  box-shadow: 0 6px 18px var(--rdr-shadow);
  font-size: 18px;
  line-height: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0.95;
  transition: transform 0.15s ease, color 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}

#rdr-back-top:hover {
  color: var(--rdr-accent-ink);
  border-color: var(--rdr-accent);
  transform: translateY(-2px);
  box-shadow: 0 10px 24px var(--rdr-shadow-deep);
}

#rdr-back-top[hidden] { display: none; }

/* ---------- Cover ---------- */

.rdr-cover {
  text-align: center;
  padding-bottom: 24px;
}

.rdr-cover-title {
  position: relative;
  font-family: var(--rdr-font-latin), var(--rdr-font-body);
  font-size: clamp(2.1rem, 6vw, 3.6rem);
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: 0.04em;
  color: var(--rdr-fg);
  padding-bottom: 0.45em;
  margin-bottom: 0.7em;
}

.rdr-cover-title::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0;
  transform: translateX(-50%);
  width: 3.6em;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, transparent 0%, var(--rdr-accent) 32%, var(--rdr-olive) 68%, transparent 100%);
}

.rdr-cover-subtitle {
  font-family: var(--rdr-font-latin), var(--rdr-font-body);
  font-style: italic;
  font-size: clamp(1.05rem, 2.6vw, 1.35rem);
  color: var(--rdr-muted);
  margin-bottom: 0.9em;
}

.rdr-cover-desc {
  max-width: 34em;
  margin: 0 auto 1.2em;
  font-size: 1.02em;
  line-height: 1.9;
  color: var(--rdr-muted);
}

.rdr-cover-stat {
  display: inline-block;
  margin: 1.4em 0 0.4em;
  padding: 0.4em 1.2em;
  border: 1px solid var(--rdr-olive);
  border-radius: 999px;
  background: var(--rdr-olive-soft);
  font-family: var(--rdr-font-ui);
  font-size: 0.88em;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--rdr-olive-ink);
}

.rdr-cover-resume,
.rdr-cover-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5em;
  margin: 0.8em 0.4em 0;
  padding: 0.85em 2.3em;
  border-radius: 999px;
  font-family: var(--rdr-font-ui);
  font-size: 1.02em;
  font-weight: 600;
  letter-spacing: 0.04em;
  cursor: pointer;
  text-decoration: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background-color 0.15s ease, border-color 0.15s ease;
}

.rdr-cover-cta {
  background: var(--rdr-accent);
  color: var(--rdr-on-accent);
  border: 1px solid var(--rdr-accent);
  box-shadow: 0 8px 22px var(--rdr-shadow);
}

.rdr-cover-cta:hover {
  background: var(--rdr-accent-ink);
  border-color: var(--rdr-accent-ink);
  transform: translateY(-2px);
  box-shadow: 0 12px 28px var(--rdr-shadow-deep);
}

.rdr-cover-resume {
  background: transparent;
  color: var(--rdr-olive-ink);
  border: 1px solid var(--rdr-olive);
}

.rdr-cover-resume:hover {
  background: var(--rdr-olive-soft);
  transform: translateY(-2px);
}

/* TOC section on the cover */
.rdr-cover-toc {
  margin-top: 4.5em;
  padding-top: 2em;
  border-top: 1px solid var(--rdr-rule);
  text-align: left;
}

.rdr-cover .rdr-part-title {
  display: flex;
  align-items: center;
  gap: 1.1em;
  margin: 2.4em 0 0.5em;
  font-family: var(--rdr-font-ui);
  font-size: 0.82em;
  font-weight: 600;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--rdr-olive-ink);
}

.rdr-cover .rdr-part-title::before,
.rdr-cover .rdr-part-title::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--rdr-rule);
}

.rdr-cover .rdr-toc-item {
  display: flex;
  align-items: baseline;
  gap: 1em;
  padding: 0.75em 0.2em;
  border-bottom: 1px dashed var(--rdr-rule);
  font-family: var(--rdr-font-body);
  font-size: 1.05em;
  line-height: 1.6;
  color: var(--rdr-fg);
  transition: color 0.15s ease, padding-left 0.15s ease;
}

.rdr-cover .rdr-toc-item:hover {
  color: var(--rdr-accent-ink);
  padding-left: 0.45em;
}

.rdr-cover .rdr-toc-item.active {
  color: var(--rdr-accent-ink);
  font-weight: 600;
}

/* ---------- Chapter ---------- */

.rdr-chapter-title {
  position: relative;
  font-family: var(--rdr-font-latin), var(--rdr-font-body);
  font-size: clamp(1.7rem, 4.5vw, 2.4rem);
  font-weight: 600;
  line-height: 1.45;
  letter-spacing: 0.03em;
  text-align: center;
  color: var(--rdr-fg);
  padding-bottom: 0.5em;
  margin-bottom: 1.6em;
}

.rdr-chapter-title::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0;
  transform: translateX(-50%);
  width: 3em;
  height: 1px;
  background: linear-gradient(90deg, transparent 0%, var(--rdr-accent) 100%);
}

.rdr-chapter-body {
  font-family: var(--rdr-font-body);
  line-height: 1.95;
  text-align: justify;
  text-justify: inter-ideograph;
  word-break: break-word;
}

/* paragraphs — consecutive paragraphs get the classic CJK 2em indent */
.rdr-chapter-body p {
  margin: 0 0 1.15em;
}

.rdr-chapter-body p + p {
  text-indent: 2em;
}

.rdr-chapter-body h2 {
  position: relative;
  margin: 2em 0 0.85em;
  padding-left: 0.75em;
  font-family: var(--rdr-font-latin), var(--rdr-font-body);
  font-size: 1.42em;
  font-weight: 600;
  line-height: 1.5;
  color: var(--rdr-accent-ink);
  text-align: left;
}

.rdr-chapter-body h2::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.2em;
  bottom: 0.2em;
  width: 3px;
  border-radius: 2px;
  background: linear-gradient(180deg, var(--rdr-accent) 0%, var(--rdr-olive) 100%);
}

.rdr-chapter-body h3 {
  margin: 1.7em 0 0.7em;
  font-family: var(--rdr-font-latin), var(--rdr-font-body);
  font-size: 1.2em;
  font-weight: 600;
  line-height: 1.5;
  color: var(--rdr-olive-ink);
  text-align: left;
}

.rdr-chapter-body h4 {
  margin: 1.5em 0 0.6em;
  font-size: 1.05em;
  font-weight: 600;
  color: var(--rdr-faint);
  text-align: left;
}

.rdr-chapter-body strong {
  color: var(--rdr-accent-ink);
  font-weight: 700;
}

.rdr-chapter-body em {
  font-style: italic;
}

.rdr-chapter-body a {
  color: var(--rdr-accent);
  border-bottom: 1px solid var(--rdr-accent-soft);
  transition: color 0.15s ease, border-color 0.15s ease;
}

.rdr-chapter-body a:hover {
  color: var(--rdr-accent-ink);
  border-bottom-color: var(--rdr-accent);
}

/* blockquote — callout */
.rdr-chapter-body blockquote {
  margin: 1.7em 0;
  padding: 1.05em 1.5em;
  background: var(--rdr-quote-bg);
  border-left: 3px solid var(--rdr-accent);
  border-radius: 0 var(--rdr-radius) var(--rdr-radius) 0;
  color: var(--rdr-muted);
  font-family: var(--rdr-font-latin), var(--rdr-font-body);
  font-size: 1.02em;
}

.rdr-chapter-body blockquote p:last-child {
  margin-bottom: 0;
}

.rdr-chapter-body blockquote p + p {
  text-indent: 0;
}

/* hr — ornamental divider */
.rdr-chapter-body hr {
  position: relative;
  height: 1px;
  width: min(70%, 13em);
  margin: 2.8em auto;
  border: none;
  background: linear-gradient(90deg, transparent 0%, var(--rdr-rule) 50%, transparent 100%);
}

.rdr-chapter-body hr::after {
  content: "✦";
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  padding: 0 0.7em;
  background: var(--rdr-bg);
  color: var(--rdr-accent);
  font-size: 0.85em;
}

/* lists */
.rdr-chapter-body ol,
.rdr-chapter-body ul {
  margin: 0 0 1.3em;
  padding-left: 0;
  list-style: none;
}

.rdr-chapter-body li {
  margin: 0.5em 0;
  line-height: 1.85;
}

.rdr-chapter-body ul li {
  position: relative;
  padding-left: 1.5em;
}

.rdr-chapter-body ul li::before {
  content: "";
  position: absolute;
  left: 0.35em;
  top: 0.72em;
  width: 0.42em;
  height: 0.42em;
  border-radius: 50%;
  background: var(--rdr-olive);
}

.rdr-chapter-body ol {
  counter-reset: rdr-list;
}

.rdr-chapter-body ol li {
  counter-increment: rdr-list;
  position: relative;
  padding-left: 1.7em;
}

.rdr-chapter-body ol li::before {
  content: counter(rdr-list) ".";
  position: absolute;
  left: 0;
  top: 0;
  font-family: var(--rdr-font-latin), var(--rdr-font-body);
  font-weight: 600;
  color: var(--rdr-accent);
}

/* code */
.rdr-chapter-body code {
  font-family: var(--rdr-font-mono);
  font-size: 0.86em;
  padding: 0.18em 0.42em;
  border: 1px solid var(--rdr-border);
  border-radius: 5px;
  background: var(--rdr-surface-2);
  color: var(--rdr-accent-ink);
  word-break: break-word;
}

.rdr-chapter-body pre {
  margin: 1.5em 0;
  padding: 1.1em 1.3em;
  overflow-x: auto;
  border: 1px solid var(--rdr-border);
  border-radius: var(--rdr-radius);
  background: var(--rdr-surface);
  line-height: 1.7;
  text-align: left;
}

.rdr-chapter-body pre code {
  padding: 0;
  border: none;
  background: none;
  color: var(--rdr-fg);
  font-size: 0.88em;
}

/* tables & media (defensive, for marked output) */
.rdr-chapter-body table {
  width: 100%;
  margin: 1.5em 0;
  border-collapse: collapse;
  font-size: 0.95em;
  text-align: left;
}

.rdr-chapter-body th,
.rdr-chapter-body td {
  padding: 0.6em 0.9em;
  border: 1px solid var(--rdr-border);
}

.rdr-chapter-body th {
  background: var(--rdr-surface);
  color: var(--rdr-accent-ink);
  font-weight: 600;
}

.rdr-chapter-body img {
  max-width: 100%;
  height: auto;
  border-radius: var(--rdr-radius);
  margin: 0.5em auto;
  display: block;
}

/* ---------- Error box ---------- */

.rdr-error {
  max-width: var(--rdr-measure);
  margin: 3em auto;
  padding: 1.3em 1.6em;
  border: 1px solid var(--rdr-accent);
  border-radius: var(--rdr-radius);
  background: var(--rdr-error-bg);
  color: var(--rdr-error-fg);
  font-family: var(--rdr-font-ui);
  font-size: 0.95em;
  line-height: 1.8;
  text-align: left;
}

/* ---------- Footer navigation ---------- */

#rdr-foot {
  flex: none;
  width: 100%;
  max-width: var(--rdr-measure);
  margin: 0 auto;
  padding: 3em clamp(20px, 5vw, 40px) 4.5em;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

#rdr-foot button,
#rdr-foot a,
#rdr-foot-prev,
#rdr-foot-next {
  flex: 1 1 120px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5em;
  min-height: 46px;
  padding: 0.7em 1em;
  border: 1px solid var(--rdr-border);
  border-radius: var(--rdr-radius);
  background: var(--rdr-surface);
  font-family: var(--rdr-font-ui);
  font-size: 0.95em;
  font-weight: 500;
  color: var(--rdr-fg);
  transition: border-color 0.15s ease, color 0.15s ease, background-color 0.15s ease, transform 0.1s ease;
}

#rdr-foot button:hover {
  border-color: var(--rdr-accent);
  color: var(--rdr-accent-ink);
  background: var(--rdr-accent-soft);
  transform: translateY(-1px);
}

#rdr-foot-home {
  border-color: var(--rdr-accent);
  color: var(--rdr-accent-ink);
  background: var(--rdr-accent-soft);
  font-weight: 600;
}

#rdr-foot-home:hover {
  background: var(--rdr-accent);
  color: var(--rdr-on-accent);
}

#rdr-foot-courseware {
  border-color: var(--rdr-olive);
  color: var(--rdr-olive-ink);
  background: var(--rdr-olive-soft);
}

#rdr-foot-courseware:hover {
  background: var(--rdr-olive);
  color: var(--rdr-on-accent);
}

/* ---------- Responsive ---------- */

@media (max-width: 820px) {

  #rdr-sidebar {
    width: 100%;
  }

  /* Scrim — only when the drawer overlays content on mobile */
  body.rdr-sidebar-open::after {
    content: "";
    position: fixed;
    top: var(--rdr-topbar-h);
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 25;
    background: var(--rdr-scrim);
    -webkit-backdrop-filter: blur(2px);
    backdrop-filter: blur(2px);
  }

  #rdr-title {
    max-width: 34vw;
    font-size: 0.95rem;
  }

  #rdr-prev .rdr-nav-label,
  #rdr-next .rdr-nav-label {
    display: none;
  }

  #rdr-prev,
  #rdr-next {
    padding: 7px;
  }

  #rdr-courseware {
    padding: 7px 10px;
    font-size: 0.8em;
  }

  #rdr-settings {
    right: 10px;
    left: 10px;
    width: auto;
  }

  #rdr-content {
    padding-top: 32px;
  }

  #rdr-back-top {
    right: 14px;
    bottom: 14px;
    width: 40px;
    height: 40px;
  }

  #rdr-foot {
    padding: 2.5em 18px 4em;
    gap: 10px;
  }

  #rdr-foot button,
  #rdr-foot a {
    flex-basis: calc(50% - 5px);
  }

  #rdr-sidebar .rdr-part-title {
    padding-left: 18px;
  }

  #rdr-sidebar .rdr-toc-item {
    padding-left: 15px;
    padding-right: 18px;
  }
}

/* ---------- Reduced motion ---------- */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }

  html { scroll-behavior: auto; }
}