.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--accent);
  transform-origin: 0 50%;
  transform: scaleX(0);
  z-index: 100;
  pointer-events: none;
}

.book-layout {
  display: grid;
  grid-template-columns: clamp(190px, 16vw, 280px) 1fr;
  gap: clamp(1.5rem, 3vw, 3rem);
  width: 100%;
  max-width: 100%;
  margin: 0;
  padding: 2rem clamp(1rem, 3vw, 2rem) 3.5rem;
  counter-reset: post;
}

.book-layout:has(.book-toc) {
  grid-template-columns: clamp(190px, 16vw, 280px) minmax(0, 1fr) clamp(180px, 14vw, 240px);
}

.book-toc {
  align-self: start;
  position: sticky;
  top: calc(var(--header-height, 76px) + 1rem);
  max-height: calc(100vh - var(--header-height, 76px) - 2rem);
  overflow-y: auto;
  padding-left: 1.25rem;
  border-left: 1px solid var(--border);
  font-size: 0.95rem;
  line-height: 1.5;
}

.book-toc-title {
  margin: 0 0 0.9rem;
  color: var(--muted);
  font-family: var(--font-main);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.book-toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.book-toc-item + .book-toc-item {
  margin-top: 0.15rem;
}

.book-toc-h3 {
  padding-left: 0.9rem;
}

.book-toc a {
  display: block;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  color: var(--muted);
  border-left: 2px solid transparent;
  transition: color 0.1s ease, border-color 0.1s ease;
}

.book-toc a:hover {
  color: var(--text);
}

.book-toc a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: var(--accent-soft);
}

.book-sidebar {
  align-self: start;
  position: sticky;
  top: calc(var(--header-height, 76px) + 1rem);
  max-height: calc(100vh - var(--header-height, 76px) - 2rem);
  overflow-y: auto;
  padding-right: 1.5rem;
  border-right: 1px solid var(--border);
}

.sidebar-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  border: 1px solid var(--border-strong);
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.02);
  color: var(--text);
  cursor: pointer;
}

.sidebar-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.sidebar-toggle .bars {
  display: inline-flex;
  flex-direction: column;
  gap: 4px;
  width: 18px;
}

.sidebar-toggle .bars::before,
.sidebar-toggle .bars::after,
.sidebar-toggle .bars span {
  content: "";
  display: block;
  height: 2px;
  background: currentColor;
  border-radius: 2px;
}

.sidebar-backdrop {
  display: none;
}

.sidebar-title {
  margin: 0 0 1.6rem;
  font-size: 1rem;
  letter-spacing: -0.03em;
}

.sidebar-title a {
  color: var(--accent);
}

.sidebar-part + .sidebar-part {
  margin-top: 1.4rem;
}

.sidebar-part h3 {
  margin: 0 0 0.6rem;
  color: var(--muted);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

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

.sidebar-list li {
  counter-increment: post;
}

.sidebar-list li + li {
  margin-top: 0.15rem;
}

.sidebar-list a,
.sidebar-list span {
  display: block;
  position: relative;
  padding: 0.4rem 0.6rem 0.4rem 2.3rem;
  color: var(--muted);
  font-size: 0.95rem;
  line-height: 1.5;
  border-radius: 6px;
}

.sidebar-list a::before,
.sidebar-list span::before {
  content: counter(post, decimal-leading-zero);
  position: absolute;
  left: 0.55rem;
  color: var(--faint);
  font-size: 0.82rem;
}

.sidebar-list li.disabled span {
  color: var(--faint);
  opacity: 0.6;
  cursor: not-allowed;
}

.sidebar-list a:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.02);
}

.sidebar-list a.active {
  color: var(--accent);
  background: var(--accent-soft);
}

.sidebar-list a.active::before {
  color: var(--accent);
}

.sidebar-back {
  display: inline-block;
  margin-top: 1.6rem;
  color: var(--muted);
  font-size: 0.85rem;
}

.sidebar-back:hover {
  color: var(--accent);
}

.book-content {
  min-width: 0;
  max-width: 100%;
  font-family: var(--font-text);
  font-size: 1.125rem;
  line-height: 1.7;
}

.post-header {
  margin-bottom: 2.5rem;
}

.post-eyebrow {
  display: block;
  margin-bottom: 0.6rem;
  color: var(--faint);
  font-family: var(--font-main);
  font-size: 0.78rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.post-header h1 {
  margin: 0;
  max-width: none;
  font-family: var(--font-text);
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  font-weight: 600;
  letter-spacing: -0.02em;
}

.post-header h1::after {
  width: 48px;
  height: 3px;
  margin-top: 1rem;
}

.book-content p {
  color: var(--text);
  text-align: justify;
  hyphens: auto;
}

.book-content p + p {
  margin-top: 1.1rem;
}

.book-content h2 {
  margin: 2.4rem 0 1rem;
  font-family: var(--font-text);
  font-size: 1.6rem;
  line-height: 1.25;
  letter-spacing: -0.02em;
  font-weight: 600;
  color: var(--text);
}

.book-content h3 {
  margin: 2rem 0 0.8rem;
  font-family: var(--font-text);
  font-size: 1.25rem;
  line-height: 1.3;
  letter-spacing: -0.015em;
  font-weight: 600;
  color: var(--text);
}

.book-content a {
  color: var(--accent);
  text-decoration: none;
}

.book-content a:hover {
  text-decoration: underline;
  text-decoration-color: var(--accent);
  text-underline-offset: 3px;
}

.book-content p a[href^="http://"]::after,
.book-content p a[href^="https://"]::after,
.book-content li a[href^="http://"]::after,
.book-content li a[href^="https://"]::after {
  content: "↗";
  display: inline-block;
  margin-left: 0.15em;
  font-size: 0.78em;
  color: var(--faint);
  vertical-align: 0.05em;
}

.book-content h2 .heading-link,
.book-content h3 .heading-link {
  color: inherit;
  text-decoration: none;
}

.book-content h2 .heading-link:hover,
.book-content h3 .heading-link:hover {
  color: var(--accent);
  text-decoration: none;
}

.book-content h2[id],
.book-content h3[id] {
  position: relative;
  scroll-margin-top: calc(var(--header-height, 76px) + 1rem);
}

.book-content h2[id]::before,
.book-content h3[id]::before {
  content: "#";
  position: absolute;
  right: calc(100% + 0.35rem);
  color: var(--faint);
  font-weight: 400;
  opacity: 0;
  transition: opacity 0.15s ease;
  pointer-events: none;
}

.book-content h2[id]:hover::before,
.book-content h3[id]:hover::before {
  opacity: 1;
}

.book-content ul,
.book-content ol {
  margin: 1.1rem 0;
  padding-left: 1.6rem;
}

.book-content li {
  margin-top: 0.4rem;
}

.book-content li > p {
  margin: 0;
}

.book-content blockquote {
  margin: 1.4rem 0;
  padding: 0.6rem 1.2rem;
  border-left: 3px solid var(--accent);
  background: rgba(88, 209, 116, 0.05);
  color: var(--muted);
}

.book-content .alert {
  margin: 1.4rem 0;
  padding: 0.9rem 1.2rem;
  border-left: 3px solid var(--alert-color);
  border-radius: 6px;
  background: var(--alert-bg);
  color: var(--text);
}

.book-content .alert p {
  margin: 0;
  text-align: left;
}

.book-content .alert p + p {
  margin-top: 0.6rem;
}

.book-content .alert-title {
  margin-bottom: 0.4rem;
  color: var(--alert-color);
  font-family: var(--font-main);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.book-content .alert-note {
  --alert-color: #4cb4ff;
  --alert-bg: rgba(76, 180, 255, 0.07);
}

.book-content .alert-tip {
  --alert-color: var(--accent);
  --alert-bg: var(--accent-soft);
}

.book-content .alert-important {
  --alert-color: #c4a7e7;
  --alert-bg: rgba(196, 167, 231, 0.08);
}

.book-content .alert-warning {
  --alert-color: #f0c674;
  --alert-bg: rgba(240, 198, 116, 0.08);
}

.book-content .alert-caution {
  --alert-color: #ff7575;
  --alert-bg: rgba(255, 117, 117, 0.08);
}

.book-content hr {
  margin: 2.4rem 0;
  border: 0;
  border-top: 1px solid var(--border);
}

.book-content code {
  padding: 0.12em 0.4em;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.04);
  color: var(--accent);
  font-family: var(--font-code);
  font-size: 0.9em;
  font-feature-settings: "calt" 1, "liga" 0;
}

.book-content pre {
  margin: 1.4rem 0;
  padding: 1rem 1.2rem;
  overflow-x: auto;
  border-radius: 8px;
  border: 1px solid var(--border);
  font-family: var(--font-code);
  font-size: 1rem;
  line-height: 1.6;
  font-feature-settings: "calt" 1, "liga" 0;
}

/* In light mode, Chroma's diff insert/delete tokens inherit a dark highlight
   background from the dark palette (chroma-dark.css sets background-color on
   .gi/.gd; chroma-light.css overrides only color). Reset the background so
   the cream code container reads cleanly - the green/red text alone is
   enough to signal the diff. */
html[data-theme="light"] .chroma .gi,
html[data-theme="light"] .chroma .gd {
  background: transparent;
}

.book-content pre code {
  padding: 0;
  background: transparent;
  color: inherit;
  font-size: inherit;
  border-radius: 0;
}

.code-block {
  position: relative;
  margin: 1.4rem 0;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
}

.code-block pre {
  margin: 0;
  border: 0;
  border-radius: 0;
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.35rem 0.6rem 0.35rem 0.9rem;
  background: rgba(255, 255, 255, 0.03);
  border-bottom: 1px solid var(--border);
}

.code-lang {
  color: var(--faint);
  font-family: var(--font-code);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  user-select: none;
}

.code-block .copy-btn {
  padding: 0.2rem 0.55rem;
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  background: var(--copy-btn-bg);
  color: var(--muted);
  font-family: var(--font-code);
  font-size: 0.7rem;
  letter-spacing: 0.02em;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.code-block:hover .copy-btn,
.code-block .copy-btn:focus-visible {
  opacity: 1;
}

.code-block .copy-btn:hover {
  color: var(--accent);
  border-color: var(--accent);
}

.book-content img {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
}

.book-content .diagram {
  margin: 1.8rem 0;
  padding: 0;
  display: flex;
  justify-content: center;
  overflow-x: auto;
}

.book-content .register-table code {
  padding: 0;
  background: transparent;
  color: inherit;
}

.book-content .stack-frame {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  font-family: var(--font-code);
  font-size: 0.85rem;
}

.book-content .stack-frame .stack-aside {
  margin-bottom: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text);
  font-family: var(--font-main);
  font-size: 0.78rem;
  font-weight: 600;
}

.book-content .stack-frame .stack-arrow {
  margin-left: -0.1em;
  color: var(--text);
  font-size: 1.3em;
  font-weight: 900;
  vertical-align: -0.05em;
}

.book-content .stack-frame .stack-cells {
  list-style: none;
  margin: 0;
  padding: 0;
  min-width: 280px;
  max-width: 360px;
}

.book-content .stack-frame .stack-cells li {
  position: relative;
  padding: 0.55rem 0.9rem;
  border: 1px solid var(--border-strong);
  background: rgba(30, 30, 46, 0.55);
  color: var(--text);
  text-align: center;
}

.book-content .stack-frame .stack-cells li + li {
  border-top: 0;
}

.book-content .stack-frame .stack-cells li.ellipsis {
  letter-spacing: 0.4em;
  color: var(--muted);
}

.book-content .stack-frame .stack-cells li.ptr-rsp::after,
.book-content .stack-frame .stack-cells li.ptr-rbp::after {
  position: absolute;
  left: calc(100% + 0.8rem);
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-code);
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent);
  white-space: nowrap;
}

.book-content .stack-frame .stack-cells li.ptr-rsp::after { content: "← RSP"; }
.book-content .stack-frame .stack-cells li.ptr-rbp::after { content: "← RBP"; }
.book-content .stack-frame .stack-cells li.ptr-rsp.ptr-rbp::after { content: "← RBP / RSP"; }

.book-content .stack-frame .stack-cells .cell-offset {
  position: absolute;
  right: calc(100% + 0.8rem);
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted);
  font-size: 0.74rem;
  white-space: nowrap;
}


.book-content p:has(> img:only-child) {
  line-height: 0;
}

.book-content p:has(> img:only-child) > img {
  display: block;
}

.book-content table {
  display: block;
  width: 100%;
  margin: 1.4rem 0;
  overflow-x: auto;
  border-collapse: collapse;
  font-size: 0.92rem;
}

.book-content th,
.book-content td {
  padding: 0.6rem 0.9rem;
  border: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}

.book-content th {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
  font-weight: 600;
}

.book-content tbody tr:nth-child(even) td {
  background: rgba(255, 255, 255, 0.015);
}

.book-content tbody tr:hover td {
  background: var(--accent-soft);
}

.post-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

.post-nav a,
.post-nav span {
  display: inline-flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: 0.75rem 1.1rem;
  border: 1px solid var(--border-strong);
  border-radius: 6px;
  font-size: 0.9rem;
}

.post-nav a:hover {
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
}

.post-nav small {
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.post-nav-prev {
  margin-right: auto;
  text-align: left;
}

.post-nav-next {
  margin-left: auto;
  text-align: right;
}

.post-nav .disabled {
  color: var(--faint);
  opacity: 0.55;
  cursor: not-allowed;
}

.post-nav .disabled small {
  color: var(--faint);
}

@media (max-width: 620px) {
  .book-content p {
    text-align: left;
    hyphens: manual;
  }

  .book-content .stack-frame .stack-cells {
    min-width: 200px;
  }

  .book-content .diagram {
    justify-content: flex-start;
    padding: 0 4.5rem;
  }
}

@media (max-width: 1180px) {
  .book-toc {
    display: none;
  }

  .book-layout:has(.book-toc) {
    grid-template-columns: clamp(190px, 16vw, 280px) 1fr;
  }
}

@media (max-width: 980px) {
  .book-layout,
  .book-layout:has(.book-toc) {
    grid-template-columns: 1fr;
    gap: 1rem;
    padding-top: 1.5rem;
  }

  .sidebar-toggle {
    display: inline-flex;
  }

  /*
   * Mobile: open sidebar swaps out the main content and joins the natural
   * document flow. Avoids iOS Safari's well-known issues with touch-scroll
   * inside a `position: fixed; overflow: auto` element.
   */
  .book-sidebar {
    display: none;
    padding: 1rem 0 2rem;
    border-right: 0;
    background: transparent;
    max-height: none;
    position: static;
  }

  body.sidebar-open .book-sidebar {
    display: block;
  }

  body.sidebar-open .book-content,
  body.sidebar-open .book-toc,
  body.sidebar-open .post-nav {
    display: none;
  }

  .sidebar-backdrop {
    display: none;
  }
}