/* ==================== Physics Book Custom Styles ==================== */
/* This file contains ONLY physics book-specific customizations */
/* Generic theme styles are in theme.css */

/* ==================== Custom Properties for Physics Book ==================== */
:root {
  /* Electromagnetics Vol. 1 colors (VT maroon/orange, after the print cover) */
  --physics-color-primary: #861f41;
  --physics-color-primary-hover: #6d1935;
  --physics-color-secondary: #5f2167;
  --physics-color-accent: #e5751f;
  --physics-color-note: #0369a1;
  --physics-color-note-bg: #f0f9ff;
  --physics-color-abstract: #0d9488;
  --physics-color-abstract-bg: #ecfdf5;
  --physics-color-glossary: #92400e;
  --physics-color-glossary-bg: #fef3c7;
  --physics-color-example: #ea580c;
  --physics-color-example-bg: #fef2f2;
  --physics-color-exercise: #7c3aed;
  --physics-color-exercise-bg: #faf5ff;
  --physics-color-solution-border: #cbd5e1;
  --physics-color-problem: #475569;
  --physics-color-target: #fef3c7;
  --physics-color-header-link: #0d9488;

  /* Layout Constants for Educational Elements */
  --abstract-margin: 30px 6rem 0 6rem;
  --abstract-padding: 15px;
  --glossary-margin: 30px 2rem 0 6rem;
  --note-margin: 30px 6rem 0 6rem;
  --example-margin-top: 30px;

  /* Typography for Educational Elements */
  --font-size-note-title: 1.5rem;
  --font-size-abstract-title: 1.8rem;
  --font-size-glossary-title: 1.5rem;

  /* Transitions */
  --transition-opacity: opacity 0.2s ease-in-out 0.1s;

  /* Touch Targets */
  --touch-target-min: 44px;
  --touch-target-md: 48px;
  --touch-target-lg: 52px;
}

/* ==================== Summary Checkmarks ==================== */

:is(.summary li:not(.visited) > .fa-check, .summary li:not(.visited) .fa-check) {
  display: none !important;
}

.summary li.visited > .fa-check,
.summary li.visited .fa-check {
  display: inline-block !important;
  inset-inline-end: auto !important;
  inset-block-start: auto !important;
}

/* ==================== Page Title and Content ==================== */

section.normal > .title {
  font-weight: bold;
  font-size: 2.5em;
}

.book .book-body .page-wrapper .page-inner section.normal {
  counter-reset: figure note exercise equation example table;
}

/* When the URL refers to in-page elements make them stand out */
:target {
  background-color: var(--physics-color-target);
}

/* ==================== Header Links ==================== */

.header-link {
  position: absolute;
  inset-inline-start: -1em;
  opacity: 0;
  transition: var(--transition-opacity);
}

:is(h1:hover, h2:hover, h3:hover, h4:hover, h5:hover, h6:hover) .header-link {
  opacity: 1;
  color: var(--physics-color-header-link) !important;
}

/* ==================== Responsive Page Width ==================== */

.book .book-body .page-wrapper .page-inner {
  max-inline-size: calc(80% - 100px);
}

@media (max-width: 1000px) {
  .book .book-body .page-wrapper .page-inner {
    max-inline-size: calc(100% - 100px);
  }
}

@media (max-width: 600px) {
  .book .book-body .page-wrapper .page-inner {
    max-inline-size: calc(100% - 50px);
  }
}

/* ==================== Figures ==================== */

.book .book-body .page-wrapper .page-inner figure {
  display: table;
  inline-size: 100%;
  counter-increment: figure;
}

.book .book-body .page-wrapper .page-inner figure img {
  display: table;
  inline-size: 50%;
}

.book .book-body .page-wrapper .page-inner figure > [data-type='title'] {
  font-weight: bold;
  font-size: small;
}

.book .book-body .page-wrapper .page-inner figure > figcaption {
  display: table-caption;
  caption-side: bottom;
  font-size: small;
}

/* Figure numbers are baked into the figcaption text at build time (print
   numbering), so no CSS counter prefix. */
.book .book-body .page-wrapper .page-inner figure > figcaption::before {
  content: '';
}

/* ==================== Abstract / Learning Outcomes ==================== */

.abstract {
  margin: var(--abstract-margin);
  padding: var(--abstract-padding);
  background-color: var(--physics-color-abstract-bg);
}

.abstract::before {
  margin: 2px 6rem 0 6rem;
  padding: 1px;
  font-size: var(--font-size-abstract-title);
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--physics-color-abstract);
  content: 'Learning Outcomes:';
}

/* ==================== Glossary ==================== */

.glossary {
  margin: var(--glossary-margin);
  padding: 10px 20px;
  background-color: var(--physics-color-glossary-bg);
}

.glossary-title {
  display: inline-block;
  color: var(--physics-color-glossary);
  font-size: var(--font-size-glossary-title);
  text-transform: uppercase;
  letter-spacing: 1px;
}

/* ==================== Equations ==================== */

.equation::before {
  content: '';
}

.equation {
  display: flex;
  justify-content: space-evenly;
  counter-increment: equation;
}

.equation::after {
  content: 'Eq.(' counter(equation) ')';
}

/* ==================== Notes ==================== */

.note {
  margin: var(--note-margin);
  padding: 15px;
  background-color: var(--physics-color-note-bg);
}

/* Note title variations */
:is(
  .note:not([data-label]).ui-has-child-title > header > .title,
  .note:not([data-label]).ui-has-child-title > .title
) {
  display: inline-block;
  color: var(--physics-color-note);
  font-size: var(--font-size-note-title);
  text-transform: uppercase;
  letter-spacing: 1px;
}

:is(
  .note:not([data-label]).ui-has-child-title > header > .title::before,
  .note:not([data-label]).ui-has-child-title > .title::before
) {
  content: 'Note: ';
}

.note:not([data-label]):not(.ui-has-child-title)::before {
  display: inline-block;
  color: var(--physics-color-note);
  font-size: var(--font-size-note-title);
  text-transform: uppercase;
  letter-spacing: 1px;
  content: 'Note';
}

:is(
  .note[data-label=''].ui-has-child-title > header > .title,
  .note[data-label=''].ui-has-child-title > .title
) {
  display: inline-block;
  color: var(--physics-color-note);
  font-size: var(--font-size-note-title);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.note[data-label='']:not(.ui-has-child-title)::before {
  display: inline-block;
  color: var(--physics-color-note);
  font-size: var(--font-size-note-title);
  text-transform: uppercase;
  letter-spacing: 1px;
}

:is(
  .note[data-label]:not([data-label='']).ui-has-child-title > header > .title,
  .note[data-label]:not([data-label='']).ui-has-child-title > .title
) {
  display: inline-block;
  color: var(--physics-color-note);
  font-size: var(--font-size-note-title);
  text-transform: uppercase;
  letter-spacing: 1px;
}

:is(
  .note[data-label]:not([data-label='']).ui-has-child-title > header > .title::before,
  .note[data-label]:not([data-label='']).ui-has-child-title > .title::before
) {
  content: attr(data-label-parent) ': ';
}

.note[data-label]:not([data-label='']):not(.ui-has-child-title)::before {
  display: inline-block;
  color: var(--physics-color-note);
  font-size: var(--font-size-note-title);
  text-transform: uppercase;
  letter-spacing: 1px;
  content: attr(data-label);
}

.book .book-body .page-wrapper .page-inner .note > section {
  padding: 5px 15px;
  border-block-start: 1px solid var(--physics-color-note);
  background-color: var(--physics-color-note-bg);
}

/* ==================== Examples ==================== */

.example {
  margin-block-start: var(--example-margin-top);
  counter-increment: example;
}

:is(
  .example:not([data-label]).ui-has-child-title > header > .title,
  .example:not([data-label]).ui-has-child-title > .title
) {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-accent);
}

.example:not([data-label]).ui-has-child-title > header > .title::before {
  content: 'Example ' counter(example) ': ';
}

.example:not([data-label]):not(.ui-has-child-title)::before {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-accent);
  content: 'Example';
}

.example[data-label=''].ui-has-child-title > header > .title {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-accent);
}

.example[data-label='']:not(.ui-has-child-title)::before {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-accent);
}

.example[data-label]:not([data-label='']).ui-has-child-title > header > .title {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-accent);
}

.example[data-label]:not([data-label='']).ui-has-child-title > header > .title::before {
  content: attr(data-label-parent) ': ';
}

.example[data-label]:not([data-label='']):not(.ui-has-child-title)::before {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-accent);
  content: attr(data-label);
}

.book .book-body .page-wrapper .page-inner .example > section {
  padding: 5px 15px;
  border-block-start: 1px solid var(--physics-color-accent);
  background-color: var(--physics-color-example-bg);
}

/* ==================== Exercises ==================== */

.exercise {
  margin-block-start: var(--example-margin-top);
}

.exercise:not([data-element-type='check-understanding']) {
  counter-increment: exercise;
}

.exercise:not([data-label]).ui-has-child-title > header > .title {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-exercise);
}

.exercise:not([data-label]).ui-has-child-title > header > .title::before {
  content: 'Exercise: ';
}

.exercise:not([data-label]):not(.ui-has-child-title)::before {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-exercise);
  content: 'Exercise ' counter(exercise);
}

:is(
  .exercise[data-label=''].ui-has-child-title > header > .title,
  .exercise[data-label=''].ui-has-child-title > .title
) {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-exercise);
}

:is(
  .exercise[data-label='']:not(.ui-has-child-title)::before,
  .exercise[data-label='']:not(.ui-has-child-title)::before
) {
  display: inline-block;
  padding: 0.1em 1em;
  font-weight: bold;
  color: #ffffff;
  background-color: var(--physics-color-exercise);
}

.book .book-body .page-wrapper .page-inner .exercise > section {
  padding: 5px 15px;
  border-block-start: 1px solid var(--physics-color-exercise);
  background-color: var(--physics-color-exercise-bg);
}

/* ==================== Problems and Solutions ==================== */

:is(.example .problem, .exercise .problem, .example .solution, .exercise .solution) {
  padding: 0.5em 1em;
}

:is(.example .solution, .exercise .solution) {
  border-block-start: 1px solid var(--physics-color-solution-border);
}

:is(.example .solution > .ui-toggle-wrapper, .exercise .solution > .ui-toggle-wrapper) {
  text-align: center;
}

:is(.example .solution > .ui-toggle-wrapper > .ui-toggle, .exercise .solution > .ui-toggle-wrapper > .ui-toggle) {
  outline: 0;
  text-align: center;
  font-weight: bold;
  min-inline-size: fit-content;
}

:is(
  .example .solution:not(.ui-solution-visible) > .ui-toggle-wrapper > button.ui-toggle::before,
  .exercise .solution:not(.ui-solution-visible) > .ui-toggle-wrapper > button.ui-toggle::before
) {
  content: 'Show Solution';
  display: inline-block;
}

:is(
  .example .solution:not(.ui-solution-visible) > section,
  .exercise .solution:not(.ui-solution-visible) > section
) {
  display: none;
}

:is(
  .example .solution.ui-solution-visible > .ui-toggle-wrapper > button.ui-toggle::before,
  .exercise .solution.ui-solution-visible > .ui-toggle-wrapper > button.ui-toggle::before
) {
  content: 'Hide Solution';
  display: inline-block;
}

:is(
  .example[data-element-type='check-understanding'] .title::before,
  .exercise[data-element-type='check-understanding'] .title::before
) {
  margin-inline-end: 0;
  content: '';
}

:is(
  .example[data-element-type='conceptual-questions'] .problem,
  .exercise[data-element-type='conceptual-questions'] .problem
) {
  border-block-start: none;
}

:is(
  .example[data-element-type='conceptual-questions'] .problem p,
  .exercise[data-element-type='conceptual-questions'] .problem p
) {
  margin: 0;
}

:is(
  .example[data-element-type='problems-exercises'] .problem::before,
  .exercise[data-element-type='problems-exercises'] .problem::before,
  .example[data-element-type='problems-exercises'] .solution::before,
  .exercise[data-element-type='problems-exercises'] .solution::before
) {
  font-weight: bold;
  color: var(--physics-color-problem);
  text-transform: uppercase;
  letter-spacing: 1px;
}

:is(
  .example[data-element-type='problems-exercises'] .problem::before,
  .exercise[data-element-type='problems-exercises'] .problem::before
) {
  content: '';
}

:is(
  .example[data-element-type='problems-exercises'] .solution::before,
  .exercise[data-element-type='problems-exercises'] .solution::before
) {
  content: '';
}

/* ==================== Chapter Numbering (Physics Book Specific) ==================== */

.book .book-summary ul.summary {
  counter-reset: chapter;
}

.book .book-summary ul.summary li.part {
  font-size: 130%;
  font-weight: bold;
  color: #1e293b;
  padding-inline-start: 15px;
}

.book .book-summary ul.summary li.part > ol {
  font-size: 70%;
  font-weight: normal;
}

.book .book-summary ul.summary ol {
  padding: 0;
}

.book .book-summary ul.summary li {
  padding-block: 10px;
  list-style-type: none;
  white-space: nowrap;
  overflow-x: hidden;
  text-overflow: ellipsis;
}

.book .book-summary ul.summary li > a {
  display: inline !important;
}

.book .book-summary ul.summary li::before {
  font-weight: bold;
}

.book .book-summary ul.summary li.chapter {
  counter-increment: chapter;
  counter-reset: section;
  white-space: normal;
}

/* Flatten the <p> wrapper so chapter number, checkmark, and title flow inline */
.book .book-summary ul.summary li.chapter > p {
  display: contents;
  margin: 0;
}

/* Chapter/section numbers are embedded in the link text by summary.njk
   (preface, end-matter, and appendix entries interleave with numbered
   chapters, so CSS counters cannot reproduce the book's numbering). */
.book .book-summary ul.summary li.chapter::before {
  content: '';
}

.book .book-summary ul.summary li.chapter > p > a {
  display: inline !important;
  font-size: 120%;
  white-space: normal;
}

.book .book-summary ul.summary li.chapter > ol > li {
  counter-increment: section;
  white-space: normal;
}

.book .book-summary ul.summary li.chapter > ol > li::before {
  content: '';
}

.book .book-summary ul.summary li.chapter > ol > li > a {
  display: inline !important;
  white-space: normal;
}

/* ==================== Page Counters ==================== */

.page {
  counter-reset: figure example exercise equation;
}

.page-title {
  font-weight: bold;
  color: var(--physics-color-secondary);
  text-transform: uppercase;
  letter-spacing: 1px;
}

/* ==================== Iframe ==================== */

iframe {
  display: block;
  inline-size: 100%;
}

/* ==================== Enhanced Mobile Touch Interactions ==================== */

/* Prevent text selection during swipe gestures */
.book .book-body {
  -webkit-touch-callout: none;
  -webkit-user-select: none;
  user-select: none;
}

/* Allow text selection in actual content */
.book .book-body .page-inner {
  -webkit-user-select: text;
  user-select: text;
}

/* Smooth transitions for swipe feedback */
.book .book-body .page-wrapper {
  will-change: transform, opacity;
}

/* Larger touch targets for navigation buttons on mobile */
@media (max-width: 768px) {
  .book .book-body .navigation {
    min-inline-size: 48px;
    min-block-size: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 12px;
  }

  /* Enhanced tap feedback for navigation buttons */
  .book .book-body .navigation:active {
    background-color: rgb(0 0 0 / 0.1);
    transform: scale(0.95);
    transition: all 0.1s ease;
  }

  /* Improve toggle summary button touch target */
  .book .toggle-summary {
    min-inline-size: 48px;
    min-block-size: 48px;
    padding: 12px;
  }

  .book .toggle-summary:active {
    background-color: rgb(0 0 0 / 0.1);
    transform: scale(0.95);
  }

  /* Enhanced touch targets for dark mode and PDF buttons */
  :is(.book .book-body .dark-mode-toggle, .book .book-body .pdf-download-btn) {
    min-inline-size: var(--touch-target-min);
    min-block-size: var(--touch-target-min);
    padding: 8px;
  }

  :is(.book .book-body .dark-mode-toggle:active, .book .book-body .pdf-download-btn:active) {
    background-color: rgb(0 0 0 / 0.2);
  }

  /* Improve spacing for summary links */
  .book .book-summary ul.summary li a {
    padding: 12px 15px;
    min-block-size: var(--touch-target-min);
    display: flex;
    align-items: center;
  }

  /* Keep chapter/section numbers inline with their titles */
  :is(
    .book .book-summary ul.summary li.chapter > p > a,
    .book .book-summary ul.summary li.chapter > ol > li > a
  ) {
    display: inline !important;
    white-space: normal;
  }

  /* Better active state for summary links */
  .book .book-summary ul.summary li a:active {
    background-color: rgb(0 0 0 / 0.08);
  }
}

/* Extra small screens - more touch-friendly */
@media (max-width: 480px) {
  .book .book-body .navigation {
    min-inline-size: var(--touch-target-lg);
    min-block-size: var(--touch-target-lg);
    padding: 14px;
    font-size: 20px;
  }

  .book .book-summary ul.summary li a {
    padding: 14px 16px;
    min-block-size: var(--touch-target-md);
  }
}

/* Add subtle visual feedback for swipe direction indicators */
body.dark-mode .book .book-body .navigation:active {
  background-color: rgb(255 255 255 / 0.1);
}

body.dark-mode .book .toggle-summary:active {
  background-color: rgb(255 255 255 / 0.1);
}

body.dark-mode .book .book-summary ul.summary li a:active {
  background-color: rgb(255 255 255 / 0.08);
}

/* ================================================================
   University Physics (CNXML build) additions.
   The build generates real chapter-scoped numbers (Figure 1.5,
   Equation 2.10...), so the CSS-counter auto-numbering above is
   disabled here in favor of explicit spans.
   ================================================================ */

/* Equations: numbers come from <span class="equation-number"> */
.equation {
  counter-increment: none;
  justify-content: center;
  position: relative;
  align-items: center;
  overflow-x: auto;
  padding: 0.25em 0;
}

.equation::after {
  content: none;
}

.equation > .equation-number {
  position: absolute;
  right: 0.5em;
  font-weight: bold;
}

/* Figures: numbers come from <span class="figure-number"> */
.book .book-body .page-wrapper .page-inner figure {
  counter-increment: none;
}

.book .book-body .page-wrapper .page-inner figure > figcaption::before {
  content: none;
}

.figure-number,
.table-number,
.table-title {
  font-weight: bold;
}

figure.splash img {
  inline-size: 100%;
}

/* Learning objectives (module abstract) */
.abstract::before {
  display: block;
  margin: 0 0 0.5em 0;
  content: 'Learning Objectives';
}

/* Note flavors */
.note.equation-callout {
  border-inline-start: 4px solid var(--physics-color-primary, #3884ff);
}

.note.problem-solving {
  border-inline-start: 4px solid #8a5cf5;
}

.note.media-2 {
  border-inline-start: 4px solid #0ea5a4;
}

.note.check-understanding {
  border-inline-start: 4px solid #f59e0b;
}

/* Inline glossary terms */
.term {
  font-weight: bold;
}

.term.no-emphasis {
  font-weight: inherit;
}

/* Strategy / Solution / Significance headings inside examples */
h4.para-title {
  margin-block: 1em 0.25em;
}

/* Glossary definition list */
.glossary dl dt {
  font-weight: bold;
  margin-block-start: 0.75em;
}

.glossary dl dd {
  margin-inline-start: 1.5em;
}

/* Footnotes */
.footnotes {
  font-size: 0.875em;
  color: var(--color-secondary, #555);
}

body.dark-mode .footnotes {
  color: var(--color-dark-text-muted);
}

/* Tables */
.book .book-body .page-wrapper .page-inner table {
  border-collapse: collapse;
  margin-block: 1em;
}

.book .book-body .page-wrapper .page-inner table caption {
  caption-side: top;
  text-align: start;
  padding-block: 0.5em;
}

.book .book-body .page-wrapper .page-inner td,
.book .book-body .page-wrapper .page-inner th {
  border: 1px solid var(--physics-color-table-border, #cbd5e1);
  padding: 0.35em 0.6em;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

/* Lists */
ul.list-style-none {
  list-style: none;
}

/* Embedded interactives (external simulations) */
.interactive-embed {
  margin-block: 1em;
}

.interactive-embed iframe {
  inline-size: 100%;
  aspect-ratio: 16 / 9;
  block-size: auto;
  border: 1px solid var(--physics-color-table-border, #cbd5e1);
}

/* ---------------- Sidebar: 3-volume TOC ---------------- */

/* Chapter counters restart in each volume */
.book .book-summary ul.summary li.volume {
  counter-reset: chapter;
  white-space: normal;
}

.book .book-summary ul.summary li.volume > a {
  font-size: 115%;
  font-weight: bold;
}

.book .book-summary ul.summary li.unit,
.book .book-summary ul.summary li.appendix,
.book .book-summary ul.summary li.preface {
  white-space: normal;
}

.book .book-summary ul.summary li.unit > .unit-label {
  display: inline-block;
  font-weight: bold;
  font-size: 85%;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  opacity: 0.75;
}

/* Collapsible volumes/chapters */
.book .book-summary ul.summary li.collapsible > ul,
.book .book-summary ul.summary li.collapsible > ol {
  display: none;
}

.book .book-summary ul.summary li.collapsible.expanded > ul,
.book .book-summary ul.summary li.collapsible.expanded > ol {
  display: block;
}

.toc-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: 0 4px 0 0;
  color: inherit;
  vertical-align: baseline;
}

.toc-toggle svg {
  transition: transform 0.15s ease;
}

li.collapsible.expanded > .toc-toggle svg {
  transform: rotate(90deg);
}

/* ---------------- Landing page ---------------- */

.landing {
  max-inline-size: 60rem;
  margin-inline: auto;
  padding: 1rem;
}

.volume-cards {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin-block: 1.5rem;
}

.volume-card {
  inline-size: 16rem;
  text-align: center;
  text-decoration: none;
}

.volume-card img {
  inline-size: 100%;
  border: 1px solid var(--physics-color-table-border, #cbd5e1);
  border-radius: 4px;
  box-shadow: 0 2px 6px rgb(0 0 0 / 15%);
}

.volume-card-title {
  display: block;
  margin-block-start: 0.5em;
  font-weight: bold;
}

/* Volume TOC pages */
.volume-toc .volume-cover {
  inline-size: 14rem;
  float: inline-end;
  margin: 0 0 1rem 1rem;
  border: 1px solid var(--physics-color-table-border, #cbd5e1);
}

.volume-toc ul {
  list-style: none;
  padding-inline-start: 1rem;
}

.volume-toc .toc-unit-label {
  font-weight: bold;
  text-transform: uppercase;
  font-size: 90%;
  opacity: 0.75;
  display: inline-block;
  margin-block-start: 1em;
}

.volume-toc .toc-chapter > a {
  font-weight: bold;
}

/* ==================== Electromagnetics Vol. 1 content ==================== */

/* Key-takeaway boxes (LaTeX mdframed with yellow background) */
.highlight-box {
  background: #fdf6d8;
  border: 1px solid #e8d98a;
  border-radius: 6px;
  padding: 12px 16px;
  margin-block: 16px;
}

body.dark-mode .highlight-box {
  background: #3a3520;
  border-color: #6b5f2a;
}

/* Display equations: build-time \tag{} numbers, MathJax renders */
.equation-block {
  margin-block: 12px;
  overflow-x: auto;
  overflow-y: hidden;
}

/* Worked examples */
.example-title {
  font-weight: bold;
  color: var(--physics-color-primary, #861f41);
}

/* Figures */
figure .figure-text {
  text-align: center;
  margin-block: 6px;
}

.figure-number,
.table-number {
  font-weight: bold;
}

.figure-credit {
  display: block;
  font-size: 80%;
  color: #666;
  margin-block-start: 4px;
}

body.dark-mode .figure-credit {
  color: #aaa;
}

body.dark-mode figure img {
  background: #fff; /* converted EPS figures assume a light background */
  border-radius: 4px;
  padding: 4px;
}

/* Tables (LaTeX tabular) */
.tabular-wrap {
  overflow-x: auto;
}

table.tabular {
  border-collapse: collapse;
  margin-inline: auto;
  margin-block: 12px;
}

table.tabular td {
  padding: 4px 12px;
}

table.tabular td.align-center {
  text-align: center;
}

table.tabular td.align-right {
  text-align: right;
}

table.tabular tr.topline td {
  border-block-start: 1px solid currentColor;
}

table.tabular.bottomline tr:last-child td {
  border-block-end: 1px solid currentColor;
}

/* Cross-references that could not be resolved (should not appear in CI builds) */
.missing-ref {
  color: #b91c1c;
  border-block-end: 1px dotted #b91c1c;
  cursor: help;
}

/* Text colored via LaTeX \color (used to highlight time-varying terms) */
.tex-color-blue {
  color: #2563eb;
}

body.dark-mode .tex-color-blue {
  color: #7ab5ff;
}

.tex-color-red {
  color: #b91c1c;
}

/* Continuation modules (m0085 flows inside its host section, as in print) */
.module-continuation {
  margin-block-start: 32px;
}

/* Chapter landing pages: section list */
.chapter-sections ul {
  list-style: none;
  padding-inline-start: 0;
}

.chapter-sections li {
  padding-block: 4px;
}

/* Sections not yet available (placeholder pages) */
.placeholder-note {
  background: #fef2f2;
  border: 1px solid #fecaca;
  border-radius: 6px;
  padding: 12px 16px;
}

/* Footnotes */
.footnotes {
  font-size: 90%;
}

.footnote-back {
  text-decoration: none;
}

/* Book index */
.book-index .index-letters {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-weight: bold;
  margin-block-end: 16px;
}

.book-index .index-entries {
  list-style: none;
  padding-inline-start: 0;
  columns: 2;
  column-gap: 32px;
}

@media (max-width: 700px) {
  .book-index .index-entries {
    columns: 1;
  }
}

.book-index .index-entries li {
  break-inside: avoid;
  padding-block: 2px;
}

.book-index .index-entries ul {
  list-style: none;
  padding-inline-start: 20px;
}

/* Landing page */
.landing {
  max-inline-size: 720px;
  margin-inline: auto;
}

.landing .landing-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-block: 24px;
}

.landing .landing-actions a {
  display: inline-block;
  padding: 10px 20px;
  border-radius: 6px;
  background: var(--physics-color-primary, #861f41);
  color: #fff;
  text-decoration: none;
  font-weight: bold;
}

.landing .landing-actions a.secondary {
  background: transparent;
  color: var(--physics-color-primary, #861f41);
  border: 2px solid var(--physics-color-primary, #861f41);
}

body.dark-mode .landing .landing-actions a.secondary {
  color: #e2949f;
  border-color: #e2949f;
}

.landing .chapter-list {
  list-style: none;
  padding-inline-start: 0;
}

.landing .chapter-list li {
  padding-block: 6px;
}

/* Smallcaps from LaTeX {\sc ...} */
.smallcaps {
  font-variant: small-caps;
}

/* Inline item labels from \item[...] */
.item-label {
  font-weight: bold;
}