/*
Theme: Dark Theme (dark)
Description: Dimmed palette for low-light and night viewing.
*/


/* --- Main Content Link Styling --- */
.container a, .markdown-body a {
  color: var(--color-link);
  text-decoration: none;
  transition: color 0.2s, background 0.2s;
  border-radius: 4px;
  font-weight: 500;
}
.container a:hover, .container a:focus,
.markdown-body a:hover, .markdown-body a:focus {
  color: #fff;
  background: var(--color-menu-hover);
  text-decoration: none;
  outline: none;
}


/*
  =============================
  Modern Classical Mechanics CSS
  =============================
  Color variables, layout, navigation, cards, admonitions, responsive, and utility styles.
  Cleaned and documented for clarity and maintainability.
*/

/* --- Color Variables --- */


:root {
  --color-bg: #282a31;
  --color-fg: #f9f9fb;
  --color-card: #282a31;
  --color-border: #b39ddb;
  --color-menu: #b39ddb;
  --color-menu-hover: #7c5fcf;
  --color-link: #b39ddb;
  --color-link-hover: #7c5fcf;
  --color-title: #7c5fcf;
  --color-btn: #0d3c47;
  --color-btn-hover: #b39ddb;
  --color-btn-text: #23242a;
}

html, body {
  background: var(--color-bg) !important;
  color: var(--color-fg) !important;
  font-family: system-ui, sans-serif;
  margin: 0 !important;
  padding: 0 !important;
  height: 100%;
  transition: background 0.3s, color 0.3s;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  max-width: 900px;
  width: 100%;
  margin-left: auto;
  margin-right: auto;
  margin-top: 2em;
  margin-bottom: 2em;
  padding: 1em;
  background: var(--color-card) !important;
  color: var(--color-fg) !important;
  border-radius: 12px;
  box-shadow: 0 2px 16px rgba(0,0,0,0.04);
  border: 0;
  box-sizing: border-box;
  flex: 1 0 auto;
  transition: background 0.3s, color 0.3s, border 0.3s;
}



footer {
  flex-shrink: 0;
  text-align: center;
  padding: 2em 0 1em 0;
  font-size: 0.9em;
  color: var(--color-border);
  background: var(--color-card) !important;
  border-top: 3px solid var(--color-link);
}



.markdown-body .highlight,
.markdown-body pre,
.markdown-body code,
.markdown-body .jp-Cell,
.markdown-body .jp-Notebook,
.markdown-body .jp-CodeCell,
.markdown-body .jp-MarkdownCell,
.markdown-body .jp-OutputArea,
.markdown-body .jp-InputArea,
.markdown-body .jp-Cell-inputWrapper,
.markdown-body .jp-Cell-outputWrapper,
.markdown-body .jp-OutputPrompt,
.markdown-body .jp-InputPrompt,
.markdown-body .jp-OutputArea-output,
.markdown-body .jp-OutputArea-prompt,
.markdown-body .jp-InputArea-prompt {
  background: var(--color-card) !important;
  color: var(--color-fg) !important;
}






/* Ensure main content always uses theme background and fills viewport */
.container, .markdown-body {
  background: var(--color-bg) !important;
  min-height: 100vh;
  color: var(--color-fg) !important;
}
  --jp-cell-editor-background: var(--color-card) !important;
  --jp-cell-editor-active-background: var(--color-card) !important;
  --jp-layout-color0: var(--color-card) !important;
  --jp-layout-color1: var(--color-card) !important;
  --jp-layout-color2: var(--color-card) !important;
  --jp-layout-color3: var(--color-card) !important;
  --jp-rendermime-error-background: var(--color-card) !important;
  --jp-input-background: var(--color-card) !important;
  --jp-toolbar-background: var(--color-card) !important;
  --jp-notebook-select-background: var(--color-card) !important;
  --jp-output-area-background: var(--color-card) !important;
}

body.dark .markdown-body,
body.dark .markdown-body * {
  color: var(--color-fg) !important;
  border-color: var(--color-border) !important;
}




.site-header {
  background: var(--color-card);
  margin: 0;
  padding: 0.7em 0;
  border-bottom: 3px solid var(--color-link);
}
body.dark .site-header {
  border-bottom: 3px solid var(--color-link-hover);
}
.site-title {
  text-align: center;
  margin: 0;
  font-size: 3.2em;
  font-weight: 800;
  color: var(--color-link);
  letter-spacing: 0.01em;
  line-height: 1.1;
}

.site-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 2em;
  background: var(--color-card);
  margin: 0 0 0.5em 0;
  padding: 0.5em 0;
  border: none;
  box-shadow: none;
  position: relative;
  z-index: 200;
}
.site-nav ul {
  display: flex;
  justify-content: space-evenly; /* Even horizontal spacing */
  gap: 3em; /* Increase gap for clarity */
  list-style: none;
  margin: 0;
  padding: 0;
  align-items: center;
}
.site-nav li {
  position: relative;
}
/* Only top-level nav links get the large font size */
.site-nav > ul > li > a {
  color: var(--color-link);
  text-decoration: none;
  font-weight: 500;
  font-size: 1.65em; /* Larger text */
  padding: 0.3em 1.2em; /* More horizontal padding */
  border-radius: 6px;
  transition: background 0.2s, color 0.2s;
  display: block;
}

.site-nav > ul > li > a:hover,
.site-nav > ul > li > a:focus {
  background: var(--color-menu-hover);
  color: #fff;
  text-decoration: none;
  outline: none;
}
.site-nav a {
  color: var(--color-link);
  text-decoration: none;
  font-weight: 500;
  padding: 0.3em 1.2em;
  border-radius: 6px;
  transition: background 0.2s, color 0.2s;
  display: block;
}
.site-nav a:hover,
.site-nav a:focus {
  background: var(--color-menu-hover);
  color: #fff;
  text-decoration: none;
  outline: none;
}
.site-nav li ul {
  display: none;
  position: absolute;
  left: 0;
  top: 100%;
  min-width: 180px;
  background: var(--color-card);
  box-shadow: 0 4px 24px rgba(0,0,0,0.10);
  border-radius: 8px;
  padding: 0.5em 0;
  z-index: 300;
  flex-direction: column;
  gap: 0;
}
.site-nav li:hover > ul,
.site-nav li:focus-within > ul,
.site-nav li.open > ul {
  display: flex;
}
.site-nav li ul li {
  width: 100%;
}
.site-nav li ul a {
  padding: 0.5em 1em;
  font-size: 1em;
  border-radius: 0;
}
.site-nav li ul a:hover,
.site-nav li ul a:focus {
  background: var(--color-link);
  color: #fff;
}

/* Card grid and cards */
.card-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 2em;
  justify-content: center;
  margin: 2em 0;
  background: none;
  border: none;
  box-shadow: none;
}
.card {
  background: var(--color-card) !important;
  color: var(--color-fg) !important;
  border-radius: 16px;
  box-shadow: 0 2px 16px rgba(0,0,0,0.04);
  padding: 2em 2em 1.5em 2em;
  min-width: 220px;
  max-width: 320px;
  flex: 1 1 220px;
  text-align: center;
  margin: 0;
  border: 1px solid var(--color-card);
  transition: box-shadow 0.2s, border 0.2s, background 0.2s;
}
.card:focus, .card:hover {
  box-shadow: 0 4px 24px rgba(0,0,0,0.10);
  border: 1px solid var(--color-link);
  outline: none;
  background: var(--color-card);
}
.card h2 a {
  color: var(--color-link);
  text-decoration: none;
  transition: color 0.2s;
}
.card h2 a:hover, .card h2 a:focus {
  color: var(--color-link-hover);
  text-decoration: underline;
}
.card p {
  color: var(--color-fg);
  font-size: 1.08em;
  margin-top: 0.7em;
}

/* Admonitions */
.admonition {
  margin: 1.5em 0;
  padding: 1em 1.5em 1em 2.5em;
  border-left: 6px solid var(--color-link);
  border-radius: 8px;
  background: linear-gradient(90deg, var(--color-card) 85%, var(--color-bg) 100%);
  color: var(--color-fg);
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
  position: relative;
  overflow-x: auto;
  transition: background 0.3s, color 0.3s;
}
.admonition-title {
  font-weight: bold;
  margin-bottom: 0.5em;
  font-size: 1.08em;
  display: flex;
  align-items: center;
  gap: 0.5em;
}
.admonition.note { border-left-color: #2a7fff; }
.admonition.tip { border-left-color: #00b894; }
.admonition.warning { border-left-color: #f39c12; }
.admonition.caution { border-left-color: #e17055; }
.admonition.important { border-left-color: #6c5ce7; }
.admonition-title::before {
  content: '';
  display: inline-block;
  width: 1.2em;
  height: 1.2em;
  margin-right: 0.2em;
  background-size: contain;
  background-repeat: no-repeat;
}
.admonition.note .admonition-title::before { background-image: url('data:image/svg+xml;utf8,<svg fill="#2a7fff" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg"><circle cx="8" cy="8" r="7" stroke="#2a7fff" stroke-width="2" fill="none"/><circle cx="8" cy="8" r="2" fill="#2a7fff"/></svg>'); }
.admonition.tip .admonition-title::before { background-image: url('data:image/svg+xml;utf8,<svg fill="#00b894" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg"><rect x="3" y="7" width="10" height="2" rx="1"/><rect x="7" y="3" width="2" height="10" rx="1"/></svg>'); }
.admonition.warning .admonition-title::before { background-image: url('data:image/svg+xml;utf8,<svg fill="#f39c12" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg"><polygon points="8,2 15,14 1,14" stroke="#f39c12" stroke-width="2" fill="none"/><circle cx="8" cy="11" r="1" fill="#f39c12"/><rect x="7" y="5" width="2" height="4" rx="1" fill="#f39c12"/></svg>'); }
.admonition.caution .admonition-title::before { background-image: url('data:image/svg+xml;utf8,<svg fill="#e17055" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg"><polygon points="8,2 15,14 1,14" stroke="#e17055" stroke-width="2" fill="none"/><rect x="7" y="6" width="2" height="4" rx="1" fill="#e17055"/></svg>'); }
.admonition.important .admonition-title::before { background-image: url('data:image/svg+xml;utf8,<svg fill="#6c5ce7" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg"><circle cx="8" cy="8" r="7" stroke="#6c5ce7" stroke-width="2" fill="none"/><rect x="7" y="4" width="2" height="6" rx="1" fill="#6c5ce7"/></svg>'); }
body.dark .admonition {
  background: linear-gradient(90deg, var(--color-card) 80%, var(--color-bg) 100%);
  color: var(--color-fg);
  box-shadow: 0 2px 8px rgba(0,0,0,0.18);
}
.admonition :last-child { margin-bottom: 0; }

/* --- Work in Progress Banner --- */
.wip-banner {
  border: 2px dotted var(--color-title, #7c5fcf);
  background: var(--color-bg, #fff);
  color: #000; /* Black text in light mode */
  padding: 1em 1.5em;
  margin-bottom: 2em;
  border-radius: 8px;
  font-weight: normal;
  font-size: 1.15em;
  box-shadow: none;
  outline: none;
}

html.dark .wip-banner,
body.dark .wip-banner {
  color: #fff; /* White text in dark mode */
  background: var(--color-bg, #282a31);
  border-color: var(--color-title, #7c5fcf);
}

/* Ensure sufficient contrast for accessibility */
.wip-banner a {
  color: var(--color-link, #2a7fff);
  text-decoration: underline;
  font-weight: 600;
}
.wip-banner a:focus {
  outline: 2px solid var(--color-link, #2a7fff);
  outline-offset: 2px;
}

/* Nav and toggle button */
nav {
  text-align: center;
}
/* nav a styles removed to avoid conflict with .site-nav a */

/* Toggle button: always circular, next to menu, never distorted */
.site-nav {
  position: relative;
}
.toggle-dark {
  position: absolute;
  right: 1.2em;
  top: 50%;
  transform: translateY(-50%);
  background: var(--color-link);
  color: #fff;
  border: none;
  border-radius: 50%;
  aspect-ratio: 1 / 1;
  width: 2.5em;
  min-width: 2.5em;
  min-height: 2.5em;
  max-width: 2.5em;
  max-height: 2.5em;
  font-size: 1.3em;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-sizing: border-box;
  transition: background 0.2s, color 0.2s, box-shadow 0.2s;
  z-index: 300;
}
.toggle-dark:focus, .toggle-dark:hover {
  background: var(--color-link-hover);
  color: #fff;
  outline: 2px solid var(--color-link-hover);
  outline-offset: 2px;
}

@media (max-width: 900px) {
  .site-nav {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    width: 100vw;
    z-index: 1001;
    max-height: 60vh;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    overscroll-behavior: contain;
  }
  .toggle-dark {
    position: absolute;
    right: 0.7em;
    top: 50%;
    transform: translateY(-50%);
    width: 2.3em;
    min-width: 2.3em;
    min-height: 2.3em;
    max-width: 2.3em;
    max-height: 2.3em;
    font-size: 1.1em;
  }
}

/* Download buttons for chapter sources */
.chapter-downloads {
  margin-bottom: 2em;
  padding: 1em 0 0.5em 0;
  border-bottom: 1px solid var(--color-border);
}
.download-label {
  font-weight: 500;
  margin-right: 1em;
  font-size: 1em;
}
.download-btn {
  display: inline-block;
  margin: 0.25em 0.5em 0.25em 0;
  padding: 0.6em 1.5em;
  font-size: 1.1em;
  font-weight: 700;
  color: var(--color-btn-text);
  background: var(--color-btn);
  border: 2px solid var(--color-btn);
  border-radius: 0.6em;
  text-decoration: none;
  box-shadow: 0 2px 8px rgba(0,0,0,0.10);
  transition: background 0.2s, color 0.2s, box-shadow 0.2s, border 0.2s;
  cursor: pointer;
  outline: none;
  line-height: 1.2;
  letter-spacing: 0.01em;
}
.download-btn:focus {
  outline: 3px solid var(--color-btn-hover);
  outline-offset: 2px;
  box-shadow: 0 0 0 4px rgba(255,183,77,0.18);
}

.download-btn:hover, .download-btn:focus {
  background: var(--color-btn-hover) !important;
  border-color: var(--color-btn-hover) !important;
  color: var(--color-btn-text) !important;
  text-decoration: none;
  box-shadow: 0 4px 16px rgba(0,0,0,0.16);
}

body.dark .download-btn:hover, body.dark .download-btn:focus {
  color: var(--color-btn-hover-text) !important;
}

/* Ensure images with transparency and black text remain visible in dark mode */
/*
body.dark .markdown-body img,
body.dark .card img,
body.dark img.content-img {
  background: #fff !important;
  border: 1px solid #333;
  border-radius: 4px;
}
*/
/* Explicitly set image background for light mode for future flexibility */
.markdown-body img,
.card img,
img.content-img {
  background: #fff;
  border: 1px solid #e0e0e0;
  border-radius: 4px;
}

/* Responsive styles */
@media (max-width: 900px) {
  /* .container removed: no longer used */
  main {
    max-width: 100vw;
    padding: 1em;
  }
  .card-grid {
    flex-direction: column;
    gap: 1.2em;
    align-items: stretch;
  }
  .card {
    min-width: 0;
    max-width: 100vw;
    padding: 1.2em 1em 1em 1em;
  }
  .site-nav {
    flex-direction: row;
    align-items: center;
    justify-content: space-around;
    padding: 0.5em 0 0.3em 0;
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    width: 100vw;
    background: var(--color-card);
    border-top: 1.5px solid var(--color-border);
    box-shadow: 0 -2px 12px rgba(0,0,0,0.08);
    z-index: 1001;
  }
  .site-nav ul {
    flex-direction: row;
    gap: 1.2em;
    width: 100vw;
    justify-content: space-around;
    align-items: center;
    margin: 0;
    padding: 0;
  }
  .site-nav > ul > li > a {
    font-size: 1.1em;
    padding: 0.7em 0.7em;
    border-radius: 0.5em;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-width: 60px;
  }
  .site-nav li ul {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 3.2em;
    min-width: 0;
    width: 100vw;
    background: var(--color-card);
    box-shadow: 0 -2px 12px rgba(0,0,0,0.08);
    border-radius: 0 0 12px 12px;
    padding: 0.5em 0.5em 0.7em 0.5em;
    margin: 0;
    z-index: 1102;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 0.2em;
  }
  .site-nav li ul a {
    padding: 0.9em 1.2em;
    font-size: 1.08em;
    border-radius: 0.5em;
    margin: 0.1em 0;
    background: none;
    color: var(--color-link);
    text-align: left;
    box-shadow: none;
  }
  .site-nav li ul a:hover,
  .site-nav li ul a:focus {
    background: var(--color-link);
    color: #fff;
  }
  header.site-header {
    margin-bottom: 3.5em;
  }
  body {
    padding-bottom: 4.2em;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
  }
  main {
    flex: 1 0 auto;
  }
  footer {
    flex-shrink: 0;
  }
  /* Hide dropdown arrows on mobile for clarity */
  .site-nav > ul > li > a:after {
    display: none !important;
  }
}