:root {
    --reader-shell-width: min(100vw - 40px, 680px);
    --bg: #0d0d0d;
    --text: #e8e0d4;
    --text-dim: #8a7e72;
    --accent: #c9a96e;
    --accent-dim: #5a4a2e;
    --chapter-title: #d4c4a8;
    --sidebar-bg: rgba(13,13,13,0.97);
    --border: #2a2a2a;
    --progress: #c9a96e;
    --code-text: #9ecbff;
  }
  :root[data-theme="sepia"] {
    --bg: #f5f0e8;
    --text: #000000;
    --text-dim: #8a7e72;
    --accent: #8b6914;
    --accent-dim: #c9b99a;
    --chapter-title: #5b4636;
    --sidebar-bg: rgba(245,240,232,0.97);
    --border: #d4c9a8;
    --progress: #8b6914;
    --code-text: #193a8a;
  }
  * { margin: 0; padding: 0; box-sizing: border-box; }
  
  html {
    scroll-behavior: auto;
    min-height: 100%;
    overflow-x: hidden;
    overflow-y: auto;
  }
  
  body {
    font-family: 'Exo 2', 'Source Sans 3', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.75;
    font-size: 20px;
    font-weight: 300;
    overflow-x: hidden;
    overflow-y: auto;
    min-height: 100%;
    transition: background 0.5s, color 0.5s;
  }

  .chapter-bg {
    position: fixed;
    inset: 0;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    opacity: 0;
    transition: opacity 1.6s ease;
    z-index: -2;
    pointer-events: none;
    filter: none;
  }

  @media (max-width: 1551px) {
    .chapter-bg {
      mask-image: linear-gradient(to bottom, rgba(0, 0, 0, 0.55) 0%, rgba(0, 0, 0, 0.55) 100%);
    }
  }

  .chapter-bg.visible {
    opacity: 0.60;
  }

  .reader-focus-overlay {
    display: none;
  }

  .scroll-spacer {
    width: 1px;
    height: 0;
    opacity: 0;
    pointer-events: none;
  }
  
  /* Reader container */
  .reader {
    display: none;
    max-width: 680px;
    width: var(--reader-shell-width);
    padding: 80px 32px 120px;
    height: 100vh;
    overflow: hidden;
    position: fixed;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
  }

  @media (min-width: 1552px) {
    .reader-focus-overlay {
      display: none;
      position: fixed;
      top: 0;
      bottom: 0;
      width: calc(var(--reader-shell-width) + 200px);
      left: auto;
      right: 0;
      transform: none;
      pointer-events: none;
      z-index: -1;
      backdrop-filter: blur(4px) saturate(0.68) contrast(0.86) brightness(0.64);
      background: rgba(2, 4, 8, 0.32);
      mask-image: linear-gradient(to right, rgba(0, 0, 0, 0) 0px, rgb(0, 0, 0) 100px, rgb(0, 0, 0) 100%);
    }

    :root[data-theme="sepia"] .reader-focus-overlay {
      backdrop-filter: blur(4px) saturate(0.78) contrast(0.9) brightness(1.06);
      background: rgba(255, 250, 242, 0.3);
    }

    body.reader-ready .reader-focus-overlay {
      display: block;
    }

    .reader {
      left: auto;
      right: 60px;
      transform: none;
    }

    :root[data-widescreen-layout="left"] .reader-focus-overlay {
      width: calc(var(--reader-shell-width) + 200px);
      left: 0;
      right: auto;
      transform: none;
      mask-image: linear-gradient(to right, rgb(0, 0, 0) 0%, rgb(0, 0, 0) calc(100% - 100px), rgba(0, 0, 0, 0) 100%);
    }

    :root[data-widescreen-layout="center"] .reader-focus-overlay {
      width: calc(var(--reader-shell-width) + 400px);
      left: 50%;
      right: auto;
      transform: translateX(-50%);
      mask-image: linear-gradient(to right, rgba(0, 0, 0, 0) 0px, rgb(0, 0, 0) 100px, rgb(0, 0, 0) calc(100% - 100px), rgba(0, 0, 0, 0) 100%);
    }

    :root[data-widescreen-layout="right"] .reader-focus-overlay {
      width: calc(var(--reader-shell-width) + 200px);
      left: auto;
      right: 0;
      transform: none;
      mask-image: linear-gradient(to right, rgba(0, 0, 0, 0) 0px, rgb(0, 0, 0) 100px, rgb(0, 0, 0) 100%);
    }

    :root[data-widescreen-layout="left"] .reader {
      left: 60px;
      right: auto;
      transform: none;
    }

    :root[data-widescreen-layout="center"] .reader {
      left: 50%;
      right: auto;
      transform: translateX(-50%);
    }

    :root[data-widescreen-layout="right"] .reader {
      left: auto;
      right: 60px;
      transform: none;
    }

  }
  
  /* Chapter styling */
  .chapter {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
  }
  .chapter.visible {
    opacity: 1;
    transform: translateY(0);
  }
  
  .chapter-number {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 11px;
    font-weight: 500;
    letter-spacing: 4px;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 16px;
    display: block;
  }
  
  .chapter-title {
    font-size: 2.4em;
    font-weight: 300;
    color: var(--chapter-title);
    line-height: 1.2;
    margin-bottom: 8px;
    border: none;
  }
  
  .chapter-subtitle {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 12px;
    color: var(--text-dim);
    letter-spacing: 1px;
    margin-bottom: 40px;
    padding-bottom: 24px;
    border-bottom: 1px solid var(--border);
  }
  
  .chapter p {
    position: relative;
    text-align: justify;
    hyphens: auto;
    orphans: 3;
    widows: 3;
  }

  .para-debug-label {
    position: absolute;
    left: -72px;
    top: 0.15em;
    font-family: 'Space Grotesk', sans-serif;
    font-size: 10px;
    line-height: 1;
    color: #777;
    letter-spacing: 0.2px;
    user-select: none;
    pointer-events: none;
    opacity: 0.9;
  }

  .chapter-body.render-comfortable p {
    margin-bottom: 1.2em;
    text-indent: 0;
  }

  .chapter-body.render-compact p {
    margin-bottom: 0;
    text-indent: 1.5em;
  }

  .chapter-body.render-compact p:first-of-type {
    text-indent: 0;
  }

  .chapter-body p.line-clipped {
    overflow: hidden;
  }

  .line-mask {
    position: fixed;
    left: 0;
    right: 0;
    background: var(--bg);
    pointer-events: none;
    z-index: 90;
    display: none;
  }

  .line-mask.active {
    display: block;
  }

  .page-frame-overlay {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: min(calc(100vw - 40px), 744px);
    border: 1px solid rgba(255, 255, 255, 0.45);
    background: rgba(255, 255, 255, 0.2);
    pointer-events: none;
    z-index: 85;
    display: none;
  }

  .page-frame-overlay.active {
    display: block;
  }

  .viewport-debug-overlay {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 95;
    display: none;
  }

  .viewport-debug-overlay.active {
    display: block;
  }

  .viewport-debug-line {
    position: fixed;
    left: 0;
    right: 0;
    border-top: 1px dashed rgba(255, 110, 110, 0.95);
  }

  .viewport-debug-line.bottom {
    border-top-color: rgba(110, 220, 255, 0.95);
  }

  .viewport-debug-label {
    position: fixed;
    right: 14px;
    top: 58px;
    font-family: 'Space Grotesk', sans-serif;
    font-size: 11px;
    line-height: 1.3;
    color: #fff;
    background: rgba(0, 0, 0, 0.65);
    border: 1px solid rgba(255, 255, 255, 0.35);
    border-radius: 4px;
    padding: 6px 8px;
    white-space: pre;
  }

  .chapter strong { font-weight: 500; color: var(--text); }
  .chapter em { font-style: italic; color: var(--text-dim); }

  .chapter hr {
    border: 0;
    height: auto;
    margin: 2.2em 0;
    text-align: center;
  }

  .chapter hr::before {
    content: "🐀 🐀 🐀";
    color: var(--accent-dim);
    font-size: 1.1em;
    letter-spacing: 0.2em;
  }
  
  .chapter blockquote {
    border: none;
    border-left: 2px solid var(--accent);
    padding-left: 20px;
    margin: 1.5em 0;
    color: var(--text-dim);
    font-style: italic;
  }

  .chapter .quote-line {
    color: var(--code-text);
  }
  
  .chapter h1 { border: none; font-size: 1.6em; color: var(--chapter-title); margin: 2em 0 0.5em; font-weight: 400; }
  .chapter h2 { border: none; font-size: 1.3em; color: var(--chapter-title); margin: 2em 0 0.5em; font-weight: 400; }

  .chapter pre {
    white-space: pre-wrap;
    overflow-wrap: anywhere;
    margin: 1.2em 0;
    padding: 0.9em 1em;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: rgba(0, 0, 0, 0.12);
    font-family: "IBM Plex Mono", "Fira Code", monospace;
    font-size: 0.82em;
    line-height: 1.45;
  }

  .chapter pre code {
    white-space: inherit;
  }

  .reader a {
    color: var(--accent);
    text-decoration: underline;
    text-underline-offset: 2px;
  }

  .reader a:hover {
    color: var(--chapter-title);
  }
  
  /* Section breaks */
  .section-break {
    text-align: center;
    margin: 4em 0;
    color: var(--accent-dim);
    font-size: 24px;
    letter-spacing: 12px;
  }
  
  /* Navigation dots */
  .nav-dots {
    position: fixed;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    display: flex;
    flex-direction: column;
    gap: 8px;
    z-index: 50;
  }
  .nav-dots a {
    width: 6px; height: 6px;
    border-radius: 50%;
    background: var(--border);
    display: block;
    transition: all 0.3s;
  }
  .nav-dots a.active { background: var(--accent); transform: scale(1.5); }
  .nav-dots a:hover { background: var(--accent-dim); }
  
  /* Progress bar */
  .progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent-dim), var(--accent));
    transition: width 0.2s;
    z-index: 200;
  }
  
  /* Toolbar */
  .toolbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: transparent;
    border-bottom: 1px solid transparent;
    padding: 10px 24px;
    display: flex;
    align-items: center;
    gap: 12px;
    font-family: 'Space Grotesk', sans-serif;
    font-size: 13px;
    backdrop-filter: none;
    transition: transform 0.3s, background-color 0.2s ease, border-color 0.2s ease;
  }
  .toolbar:hover {
    background: #000;
    border-bottom-color: #000;
  }
  .toolbar.hidden { transform: translateY(-100%); }
  .toolbar.deferred { visibility: hidden; }
  
  .toolbar button {
    background: transparent;
    color: var(--text-dim);
    border: 1px solid var(--border);
    padding: 4px 10px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 12px;
    font-family: inherit;
    transition: all 0.2s;
  }
  .toolbar button:hover { color: var(--accent); border-color: var(--accent); }
  
  .toolbar .title {
    flex: 1;
    text-align: center;
    font-weight: 400;
    color: var(--accent);
    font-size: 12px;
    letter-spacing: 1px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  
  .toolbar .chapter-label {
    font-size: 11px;
    color: var(--text-dim);
    min-width: 100px;
    text-align: center;
  }

  .toc-flyout {
    position: fixed;
    top: 54px;
    left: 12px;
    width: min(360px, calc(100vw - 24px));
    max-height: calc(100vh - 72px);
    overflow: auto;
    background: var(--sidebar-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: 0 14px 36px rgba(0, 0, 0, 0.35);
    padding: 8px;
    z-index: 160;
    display: none;
  }

  .toc-flyout.active {
    display: block;
  }

  .toc-item {
    width: 100%;
    display: block;
    text-align: left;
    background: transparent;
    border: 0;
    color: var(--text);
    padding: 8px 10px;
    border-radius: 6px;
    cursor: pointer;
    font-family: 'Exo 2', 'Source Sans 3', sans-serif;
    font-size: 13px;
    line-height: 1.35;
  }

  .toc-controls {
    display: grid;
    gap: 8px;
    margin: 6px 0 10px;
  }
  .toc-controls-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
  }
  .toc-controls-row.five {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }
  .toc-controls-row.three {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .toc-font-btn {
    font-weight: 500;
  }
  .toc-controls .toc-item.active {
    border: 1px solid var(--accent);
    color: var(--accent);
    background: transparent;
  }
  .toc-controls-select {
    width: 100%;
    background: transparent;
    color: var(--text-dim);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 8px 10px;
    font-family: inherit;
    font-size: 12px;
  }

  .toc-item:hover {
    background: rgba(255, 255, 255, 0.08);
  }

  .toc-item.active {
    color: var(--accent);
    background: rgba(255, 255, 255, 0.06);
  }

  .toc-divider {
    height: 1px;
    background: var(--border);
    margin: 8px 4px 10px;
    opacity: 0.7;
  }

  .resume-popover {
    position: fixed;
    left: 14px;
    bottom: 14px;
    z-index: 170;
    max-width: min(520px, calc(100vw - 28px));
    border: none;
    background: color-mix(in srgb, var(--sidebar-bg) 82%, transparent);
    border-radius: 8px;
    box-shadow: 0 10px 28px rgba(0, 0, 0, 0.3);
    padding: 8px 10px;
    display: none;
  }

  .resume-popover.active {
    display: block;
  }

  .resume-popover-title {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 12px;
    letter-spacing: 0.4px;
    color: var(--text);
    margin-bottom: 0;
  }

  .resume-popover-actions {
    display: inline-flex;
    gap: 0;
    align-items: center;
  }

  .resume-popover-row {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
  }

  .resume-popover-actions button {
    border: 1px solid var(--border);
    background: transparent;
    color: var(--text);
    border-radius: 6px;
    padding: 6px 9px;
    font-family: 'Exo 2', 'Source Sans 3', sans-serif;
    font-size: 12px;
    cursor: pointer;
  }
  .resume-split button {
    border-radius: 0;
  }
  .resume-split #resume-popover-go {
    border-top-left-radius: 6px;
    border-bottom-left-radius: 6px;
    border-right: none;
  }
  .resume-split #resume-popover-close {
    border-top-right-radius: 6px;
    border-bottom-right-radius: 6px;
  }
  #resume-popover-close {
    width: 28px;
    height: 28px;
    padding: 0;
    line-height: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    font-family: 'Space Grotesk', sans-serif;
  }
  
  .toolbar select {
    background: transparent;
    color: var(--text-dim);
    border: 1px solid var(--border);
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 12px;
    font-family: inherit;
    cursor: pointer;
  }

  .paging-next {
    position: fixed;
    right: calc((100vw - min(100vw - 40px, 680px)) / 2 + 32px);
    bottom: 20px;
    z-index: 31;
    opacity: 0;
    pointer-events: none;
    transform: translateY(8px);
    transition: opacity 0.2s ease, transform 0.2s ease;
  }
  .paging-next.active {
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
  }
  .paging-next button {
    appearance: none;
    padding: 8px 12px;
    border: none;
    border-radius: 4px;
    background: color-mix(in srgb, var(--bg) 82%, transparent);
    color: var(--accent);
    font-family: 'Space Grotesk', sans-serif;
    font-size: 11px;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    cursor: pointer;
  }
  .paging-next button:hover {
    color: var(--accent-dim);
  }
  .paging-next button:active,
  .paging-next button:focus,
  .paging-next button:focus-visible {
    background: color-mix(in srgb, var(--bg) 82%, transparent);
    color: var(--accent);
    outline: none;
    box-shadow: none;
  }

  @media (min-width: 1552px) {
    .paging-next {
      right: 92px;
    }

    :root[data-widescreen-layout="left"] .paging-next {
      left: 92px;
      right: auto;
    }

    :root[data-widescreen-layout="center"] .paging-next {
      left: auto;
      right: calc((100vw - min(100vw - 40px, 680px)) / 2 + 32px);
    }

    :root[data-widescreen-layout="right"] .paging-next {
      left: auto;
      right: 92px;
    }
  }
  
  /* Chapter transition overlay */
  .transition-overlay {
    position: fixed;
    inset: 0;
    background: var(--bg);
    z-index: 300;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.4s;
  }
  .transition-overlay.active {
    opacity: 1;
    pointer-events: all;
  }
  .transition-overlay span {
    color: var(--text-dim);
    font-family: 'Space Grotesk', sans-serif;
    font-size: 13px;
    letter-spacing: 3px;
    text-transform: uppercase;
  }
  
  /* Loading */
  #loading {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-dim);
    font-family: 'Space Grotesk', sans-serif;
    font-size: 14px;
    letter-spacing: 2px;
  }
  #loading.hidden { display: none; }

  .loading-title {
    margin-bottom: 16px;
    font-size: 16px;
  }

  .loading-progress {
    font-size: 11px;
    color: var(--accent-dim);
  }
  
  /* Cover page */
  .cover {
    text-align: center;
    padding: 120px 0 80px;
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease, transform 0.8s ease;
  }
  .cover.visible { opacity: 1; transform: translateY(0); }
  
  .cover h1 {
    font-size: 3.5em;
    font-weight: 300;
    color: var(--chapter-title);
    margin-bottom: 8px;
    letter-spacing: -1px;
  }
  .cover .subtitle {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 14px;
    font-weight: 300;
    color: var(--accent);
    letter-spacing: 6px;
    text-transform: uppercase;
    margin-bottom: 24px;
  }
  .cover .author {
    font-size: 1.3em;
    color: var(--text-dim);
    margin-bottom: 60px;
    font-style: italic;
  }
  .cover .start-btn {
    display: inline-block;
    padding: 12px 40px;
    border: 1px solid var(--accent);
    color: var(--accent);
    text-decoration: none;
    font-family: 'Inter', sans-serif;
    font-size: 12px;
    letter-spacing: 3px;
    text-transform: uppercase;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.3s;
    background: transparent;
  }
  .cover .start-btn:hover {
    background: var(--accent);
    color: var(--bg);
  }
  
  /* Scrollbar */
  @media (max-width: 768px) {
    .reader { padding: 70px 20px 100px; }
    .cover h1 { font-size: 2.2em; }
    .chapter-title { font-size: 1.8em; }
    body { font-size: 18px; }
    .nav-dots { right: 8px; }
    .paging-next { right: 40px; }
  }

  @media (max-width: 800px) {
    .toolbar {
      padding: 10px 14px;
      gap: 10px;
    }
    .toolbar > button:not(#toc-toggle),
    .toolbar > select,
    .toolbar .chapter-label {
      display: none;
    }
    .toolbar .title {
      flex: 1;
      text-align: left;
    }
  }