/* ============================================
   CSS Variables — override in your project's style.css
   ============================================ */
:root {
  --sidebar-width: 260px;
  --topbar-height: 40px;
  --sidebar-bg: #f9f6f0;
  --border-color: #3d2645;
  --text-color: #333;
  --accent-color: #b893c7;
  --arrow-bg: #f9f6f0;
  --arrow-color: #3d2645;
  --sidebar-link-color: #555;
  --background-color: #f9f6f0;
}

/* ============================================
   Base Reset
   ============================================ */
body {
  padding: 0;
  margin: 0;
  overflow-x: hidden;
}

/* ============================================
   Sidebar Backdrop
   ============================================ */
.sidebar-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 100;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.sidebar-backdrop.visible {
  opacity: 1;
  pointer-events: auto;
}

/* ============================================
   Topbar
   ============================================ */
.topbar {
  position: fixed;
  top: 0;
  left: var(--sidebar-width);
  right: 0;
  height: var(--topbar-height);
  background-color: var(--sidebar-bg);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 98;
  transition: left 0.3s ease;
}

.sidebar-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  position: absolute;
  left: 15px;
  display: none;
  transition: left 0.3s ease;
}

.hamburger {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--text-color);
  position: relative;
  transition: background-color 0.3s ease;
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  width: 20px;
  height: 2px;
  background-color: var(--text-color);
  left: 0;
  transition: transform 0.3s ease, top 0.3s ease;
}

.hamburger::before {
  top: -6px;
}

.hamburger::after {
  top: 6px;
}

.topbar-title {
  font-weight: 500;
  font-size: 16px;
  color: var(--text-color);
  display: flex;
  align-items: center;
  justify-content: center;
}

.topbar-title img {
  height: 24px;
  width: auto;
  display: block;
  object-fit: contain;
}

.topbar > a {
  text-decoration: none;
}

/* ============================================
   Sidebar Navigation
   ============================================ */
nav.sidebar {
  width: var(--sidebar-width);
  background-color: var(--sidebar-bg);
  border-right: 1px solid var(--border-color);
  position: fixed;
  top: 0;
  left: 0;
  height: 100vh;
  overflow-y: auto;
  z-index: 99;
  transition: transform 0.3s ease;
}

.banner {
  height: var(--topbar-height);
}

.banner a {
  display: flex;
  flex-direction: row;
  margin: 0 1em;
  height: 100%;
}

.banner img {
  padding-top: 8px;
  height: 50%;
  width: auto;
  display: block;
  object-fit: contain;
  object-position: left center;
}

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

.sidebar-nav li {
  margin-bottom: 2px;
}

/* Group header (non-clickable) */
.sidebar-nav li.section-label {
  margin-top: 1.5rem;
  margin-bottom: 0.4rem;
  padding: 0.5rem 12px 0.25rem;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--border-color);
  pointer-events: none;
  border-top: 1px solid var(--border-color);
}

.sidebar-nav li.section-label:first-child {
  margin-top: 0;
  border-top: none;
}

.sidebar-nav a {
  display: block;
  padding: 4px 12px;
  color: var(--sidebar-link-color);
  text-decoration: none;
  transition: background-color 0.2s;
}

.subsection-nav {
  list-style: none;
  padding-left: 20px;
  margin: 0;
  pointer-events: auto;
}

.subsection-nav a {
  padding: 2px 12px;
}

.sidebar-nav a:hover {
  background-color: #e8e8e8;
  color: #000;
}

/* Active item */
.sidebar-nav li.active > a,
.sidebar-nav li.active > p > a {
  background-color: var(--accent-color);
  color: #000;
  font-weight: 500;
}

/* Parent of active item (chapter containing the active subsection) */
.sidebar-nav li.active-parent > a {
  color: var(--accent-color);
  font-weight: 500;
}

/* Chapter number span */
.chapter-num {
  font-weight: 700;
}

/* ============================================
   Content Area
   ============================================ */
.content {
  margin-left: var(--sidebar-width);
  margin-top: var(--topbar-height);
  min-height: calc(100vh - var(--topbar-height) - 14rem);
  transition: margin-left 0.3s ease;
}

[role="doc-endnotes"] {
  margin-left: var(--sidebar-width);
}

/* ============================================
   Responsive Design
   ============================================ */

/* Desktop: show hamburger, enable sidebar collapse */
@media (min-width: 769px) {
  .sidebar-toggle {
    display: block;
  }

  nav.sidebar.hidden {
    transform: translateX(-100%);
  }

  .topbar.sidebar-closed {
    left: 0;
  }

  .sidebar-closed ~ .content,
  .sidebar-closed ~ [role="doc-endnotes"] {
    margin-left: 0;
  }
}

/* Mobile */
@media (max-width: 768px) {
  .topbar {
    left: 0;
    z-index: 100;
  }

  .topbar.sidebar-open {
    z-index: 102;
    background-color: transparent;
    border-bottom: none;
  }

  .topbar.sidebar-open .topbar-title {
    opacity: 0;
  }

  .sidebar-toggle {
    display: block;
    position: fixed;
    top: 11px;
    left: 15px;
    z-index: 1;
  }

  .topbar.sidebar-open .sidebar-toggle {
    position: fixed;
    left: 15px;
  }

  /* Hamburger → X animation */
  .sidebar-open .hamburger {
    background-color: transparent;
  }

  .sidebar-open .hamburger::before {
    top: 0;
    transform: rotate(45deg);
  }

  .sidebar-open .hamburger::after {
    top: 0;
    transform: rotate(-45deg);
  }

  .content {
    margin-left: 0;
  }

  nav.sidebar {
    transform: translateX(-100%);
    z-index: 101;
  }

  nav.sidebar:not(.hidden) {
    transform: translateX(0);
  }

  [role="doc-endnotes"] {
    margin-left: 0;
  }
}

/* ============================================
   Navigation Arrows
   ============================================ */
.nav-arrows {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin-top: 3rem;
  margin-left: var(--sidebar-width);
  padding: 0 2rem 2rem 2rem;
  transition: margin-left 0.3s ease;
}

.nav-arrow {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  background-color: var(--arrow-bg);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  color: var(--accent-color);
  text-decoration: none;
  transition: all 0.2s ease;
  min-width: 120px;
}

.nav-arrow:hover {
  background-color: var(--accent-color);
  border-color: var(--accent-color);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.15);
}

.nav-arrow .arrow-icon {
  font-size: 1.2em;
  font-weight: bold;
  color: var(--arrow-color);
}

.nav-arrow .arrow-text {
  font-size: 0.9rem;
  color: var(--arrow-color);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.prev-arrow {
  justify-content: flex-start;
  margin-right: auto;
  margin-left: 2rem;
}

.next-arrow {
  justify-content: flex-end;
  margin-left: auto;
  flex-direction: row-reverse;
}

.desktop-nav {
  display: flex;
}

.mobile-nav {
  display: none;
}

@media (max-width: 768px) {
  .desktop-nav {
    display: none;
  }

  .mobile-nav {
    display: flex;
  }

  .nav-arrows {
    margin-left: 0;
    padding: 0 1rem 2rem 1rem;
  }

  .mobile-nav .nav-arrow {
    flex: 1;
    min-width: auto;
  }

  .mobile-nav .arrow-text {
    font-size: 0.85rem;
  }

  .prev-arrow {
    margin-left: 0;
  }
}

@media (min-width: 769px) {
  .sidebar-closed ~ .nav-arrows {
    margin-left: 0;
  }
}

@media (min-width: 768px) {
  .desktop-nav .arrow-text {
    max-width: 250px;
  }
}

@media (min-width: 1024px) {
  .desktop-nav .arrow-text {
    max-width: 350px;
  }
}