style.css

/* ============================================
   Google Fonts Import
   ============================================ */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

/* ============================================
   Theme — overrides rheobook package defaults
   ============================================ */
:root:root, html:root {
  /* High-contrast neutral theme with regional warm accents (Terracotta) */
  --background-color: #ffffff;      /* Crisp pure white */
  --sidebar-bg: #f8f9fa;            /* Neutral light gray sidebar */
  
  --primary-dark: #212529;          /* Neutral dark black for titles and active headers */
  --text-color: #343a40;            /* Dark charcoal for high-contrast reading text */
  --border-color: #e9ecef;          /* Neutral light gray for borders and lines */
  
  --accent-color: #9e3f1b;          /* Dark high-contrast terracotta for active states (passes WCAG AAA) */
  --link-color: #b34d28;            /* Warm copper/terracotta for links */
  --quote-color: #495057;           /* Neutral dark gray for blockquotes */
  
  --arrow-bg: #ffffff;
  --arrow-color: #212529;
  --sidebar-link-color: #495057;
  --sidebar-hover-bg: #e9ecef;      /* Sidebar link hover background */
  --code-bg: #f8f9fa;
  
  --sidebar-width: 260px;
  --topbar-height: 40px;
}

/* ============================================
   Base Styles
   ============================================ */
body {
  background-color: var(--background-color);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  color: var(--text-color);
}

/* Headings: Premium sans-serif styling */
h1, h2, h3, h4, h5, h6 {
  color: var(--primary-dark);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  font-weight: 600;
  line-height: 1.3;
  margin-top: 2rem;
  margin-bottom: 1rem;
  letter-spacing: -0.019em;
}

h3 {
  margin-bottom: 0.5rem;
}

ul,
ol {
  padding: 0;
  margin: 0.5rem 0 1.5rem 1.5rem;
}

li {
  margin-bottom: 0.5rem;
}

/* Links: Elegant transition and semi-transparent underlines */
a {
  color: var(--link-color);
  text-decoration: underline;
  text-decoration-color: rgba(179, 77, 40, 0.3);
  text-decoration-thickness: 1px;
  transition: all 0.2s ease;
}

a:hover {
  text-decoration-color: var(--link-color);
  color: #8c3b1e;
}

video {
  max-width: 100%;
}

/* Blockquote: Clean modern style with terracotta accent bar */
blockquote {
  position: relative;
  width: 100%;
  padding: 1.2rem 1.5rem 1.2rem 2.5rem;
  margin: 2.2rem 0;
  font-size: 1.1rem;
  font-style: italic;
  font-family: 'Inter', sans-serif;
  background-color: #f8f9fa;
  color: var(--quote-color);
  border-left: 3px solid var(--accent-color);
  border-radius: 0 6px 6px 0;
  box-sizing: border-box;
}

blockquote::before {
  content: "\201C";
  position: absolute;
  top: 0.2rem;
  left: 0.5rem;
  font-size: 3rem;
  color: rgba(158, 63, 27, 0.15); /* large subtle terracotta quote mark */
  line-height: 1;
}

section[role="doc-endnotes"] ol li a[role="doc-backlink"] {
  padding-right: 0.2em;
}

figure {
  text-align: center;
  margin: 2rem 0;
}

figure figcaption {
  font-family: 'Inter', sans-serif;
  font-style: italic;
  font-size: 0.9rem;
  color: var(--quote-color);
  margin-top: 0.5rem;
}

/* ============================================
   Code Blocks
   ============================================ */
pre {
  max-width: 100%;
  overflow-x: auto;
  margin: 1.5rem 0;
}

code {
  font-family: SFMono-Regular, Consolas, 'Liberation Mono', Menlo, monospace;
  font-size: 0.9em;
  word-wrap: break-word;
  overflow-wrap: break-word;
}

pre code {
  display: block;
  white-space: pre-wrap;
  background-color: var(--code-bg);
  border: 1px solid var(--border-color);
  padding: 1rem;
  border-radius: 6px;
  word-break: break-word;
  color: var(--primary-dark);
}

@media (max-width: 768px) {
  pre {
    overflow-x: visible;
  }

  pre code {
    white-space: pre-wrap;
    word-break: break-all;
  }
}

/* ============================================
   Tables Styling (Minimal, Clean, and Rowspan-Safe)
   ============================================ */
.content table {
  width: 100%;
  border-collapse: collapse;
  margin: 2rem 0;
  font-size: 0.95rem;
  line-height: 1.5;
  box-sizing: border-box;
}

.content th,
.content td {
  padding: 0.75rem 1rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--border-color);
  background-color: #ffffff; /* Solid white background makes rowspan cells seamless */
}

.content th {
  font-weight: 600;
  color: var(--primary-dark);
  border-bottom: 2px solid var(--border-color);
  font-size: 0.9rem;
  background-color: #f8f9fa;
}

/* Note: Zebra striping and row-hover rules are omitted to prevent coloring conflicts 
   when tables contain cells with rowspan/colspan attributes. */

.content td[colspan] {
  font-weight: 600;
  background-color: #ffffff; /* Seamless white background */
  color: var(--primary-dark); /* Bold dark text */
  text-align: left;
  font-size: 0.95rem;
  padding: 1.25rem 1rem 0.6rem 1rem; /* More top padding to separate it from the previous section */
  border-bottom: 1.5px solid var(--primary-dark); /* Strong anchor line to group it with the rows below */
  border-top: none;
}

@media (max-width: 768px) {
  .content table {
    display: block;
    width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }
}

/* ============================================
   Sidebar & Navigation Overrides (High-Contrast)
   ============================================ */
.sidebar-nav li.section-label {
  color: #495057 !important; /* High contrast section headings */
  border-top: 1px solid var(--border-color) !important;
}

.sidebar-nav a:hover {
  background-color: var(--sidebar-hover-bg) !important;
  color: var(--primary-dark) !important;
}

.sidebar-nav li.active > a,
.sidebar-nav li.active > p > a {
  background-color: var(--accent-color) !important;
  color: #ffffff !important; /* Perfect contrast on deep terracotta */
  font-weight: 600 !important;
}

.sidebar-nav li.active-parent > a {
  color: var(--accent-color) !important;
  font-weight: 600 !important;
}

/* Navigation Arrows (Next/Prev buttons) */
.nav-arrow {
  color: var(--accent-color) !important;
  background-color: var(--arrow-bg) !important;
  border: 1px solid var(--border-color) !important;
  border-radius: 6px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.nav-arrow:hover {
  background-color: var(--accent-color) !important;
  border-color: var(--accent-color) !important;
  box-shadow: 0 4px 12px rgba(158, 63, 27, 0.2) !important;
}

.nav-arrow:hover .arrow-icon,
.nav-arrow:hover .arrow-text {
  color: #ffffff !important;
}

/* ============================================
   Content Layout & Width Restricting
   ============================================ */
.content {
  padding: 1.5rem 2rem 3rem;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

[role="doc-endnotes"] {
  padding: 0 2rem 3rem;
  box-sizing: border-box;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.content h2 {
  font-size: 2.2rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.5rem;
  margin-top: 0;
  margin-bottom: 1.8rem;
}

/* Tablet and up */
@media (min-width: 768px) {
  .content {
    font-size: 1.05rem;
    line-height: 1.65;
    padding-top: 2.5rem;
  }

  blockquote {
    max-width: 32rem;
    padding: 1.2rem 1.8rem 1.2rem 2.8rem;
    margin: 2.5rem auto;
  }
}

/* Desktop and up (sidebar open): center and restrict content/arrows */
@media (min-width: 769px) {
  .content,
  [role="doc-endnotes"] {
    /* Dynamically calculate margins so that content is exactly 800px wide, centered in the remaining screen space */
    padding-left: max(2rem, calc((100vw - var(--sidebar-width) - 800px) / 2));
    padding-right: max(2rem, calc((100vw - var(--sidebar-width) - 800px) / 2));
    max-width: none;
    box-sizing: border-box;
  }

  .nav-arrows:not(.mobile-nav) {
    /* Align arrows perfectly with centered text box limits */
    padding-left: max(2rem, calc((100vw - var(--sidebar-width) - 800px) / 2));
    padding-right: max(2rem, calc((100vw - var(--sidebar-width) - 800px) / 2));
    box-sizing: border-box;
  }
}

/* Desktop and up (sidebar closed): center and restrict content/arrows */
@media (min-width: 769px) {
  .sidebar-closed~.content,
  .sidebar-closed~[role="doc-endnotes"] {
    padding-left: max(2rem, calc((100vw - 800px) / 2));
    padding-right: max(2rem, calc((100vw - 800px) / 2));
  }

  .sidebar-closed~.nav-arrows:not(.mobile-nav) {
    padding-left: max(2rem, calc((100vw - 800px) / 2));
    padding-right: max(2rem, calc((100vw - 800px) / 2));
  }
}

/* ============================================
   Image Viewer (Lightbox) Styles
   ============================================ */
.lightbox-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(15, 15, 15, 0.75);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  z-index: 10000;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s cubic-bezier(0.4, 0, 0.2, 1), visibility 0.3s;
}

.lightbox-backdrop.active {
  opacity: 1;
  visibility: visible;
}

.lightbox-wrapper {
  position: relative;
  max-width: 90vw;
  max-height: 90vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.lightbox-img {
  max-width: 90vw;
  max-height: 68vh;
  object-fit: contain;
  border-radius: 8px;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.6);
  transform: scale(0.95);
  transition: transform 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.lightbox-backdrop.active .lightbox-img {
  transform: scale(1);
}

.lightbox-caption {
  margin-top: 16px;
  margin-bottom: max(12px, env(safe-area-inset-bottom, 0px));
  color: rgba(255, 255, 255, 0.95);
  font-family: 'Inter', sans-serif;
  font-size: 0.95rem;
  text-align: center;
  max-width: 75vw;
  max-height: 15vh;
  overflow-y: auto;
  padding-right: 8px;
  box-sizing: border-box;
  line-height: 1.5;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.6);
  z-index: 10002;
  scrollbar-width: thin;
  scrollbar-color: rgba(255, 255, 255, 0.3) transparent;
  flex-shrink: 0;
  -webkit-overflow-scrolling: touch;
  touch-action: pan-y;
}

.lightbox-caption::-webkit-scrollbar {
  width: 6px;
}

.lightbox-caption::-webkit-scrollbar-track {
  background: transparent;
}

.lightbox-caption::-webkit-scrollbar-thumb {
  background-color: rgba(255, 255, 255, 0.3);
  border-radius: 3px;
}

.lightbox-caption a {
  color: #ffaa80;
  text-decoration: underline;
  text-decoration-color: rgba(255, 170, 128, 0.4);
}

.lightbox-caption a:hover {
  color: #ffc9b3;
  text-decoration-color: #ffaa80;
}

/* Close & Arrow Buttons */
.lightbox-close,
.lightbox-arrow {
  border: none;
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  color: #ffffff;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color 0.25s ease, transform 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

.lightbox-close {
  position: absolute;
  top: max(24px, env(safe-area-inset-top, 0px));
  right: max(24px, env(safe-area-inset-right, 0px));
  width: 48px;
  height: 48px;
  border-radius: 50%;
  z-index: 10002;
}

.lightbox-close:hover {
  background-color: rgba(255, 255, 255, 0.2);
  transform: scale(1.08);
}

.lightbox-close svg {
  width: 24px;
  height: 24px;
}

.lightbox-arrow {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 56px;
  height: 56px;
  border-radius: 50%;
  z-index: 10001;
}

.lightbox-arrow:hover {
  background-color: rgba(255, 255, 255, 0.2);
  transform: translateY(-50%) scale(1.08);
}

.lightbox-arrow-left {
  left: max(24px, env(safe-area-inset-left, 0px));
}

.lightbox-arrow-right {
  right: max(24px, env(safe-area-inset-right, 0px));
}

.lightbox-arrow svg {
  width: 28px;
  height: 28px;
}

/* Mobile responsive overrides */
@media (max-width: 768px) {
  .lightbox-arrow {
    width: 44px;
    height: 44px;
  }
  .lightbox-arrow-left {
    left: max(12px, env(safe-area-inset-left, 0px));
  }
  .lightbox-arrow-right {
    right: max(12px, env(safe-area-inset-right, 0px));
  }
  .lightbox-close {
    top: max(16px, env(safe-area-inset-top, 0px));
    right: max(16px, env(safe-area-inset-right, 0px));
    width: 40px;
    height: 40px;
  }
  .lightbox-caption {
    font-size: 0.85rem;
    max-width: 85vw;
    max-height: 18vh;
    overflow-y: auto;
    padding-right: 4px;
    flex-shrink: 0;
    -webkit-overflow-scrolling: touch;
    touch-action: pan-y;
  }
  .lightbox-img {
    max-height: 55vh;
  }
}

/* ============================================
   Topbar Mobile Overrides (Truncate Long Title)
   ============================================ */
@media (max-width: 768px) {
  body .topbar > a {
    display: block;
    max-width: calc(100% - 110px);
    width: 100%;
  }

  body .topbar .topbar-title {
    display: block;
    font-size: 14px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    text-align: center;
    width: 100%;
  }
}