html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: #d9d9d9;
  color: #2c2c2c;
  font-family: Georgia, "Times New Roman", serif;
  line-height: 1.6;
  font-size: 16px;
}

a {
  color: #333;
  text-decoration: underline;
  transition: color 0.2s;
}

a:hover {
  color: #000;
  text-decoration: none;
}

.frame {
  max-width: 1180px;
  margin: 0 auto;
  background: #fff;
  border-left: 1px solid #bfbfbf;
  border-right: 1px solid #bfbfbf;
  min-height: 100vh;
  box-shadow: 0 0 4px rgba(0, 0, 0, 0.1);
}

.banner {
  background: #efefef;
  border-bottom: 1px solid #bfbfbf;
  padding: 18px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.banner-left h1 {
  margin: 0;
  font-size: 2rem;
  font-weight: normal;
}

.banner-left p {
  margin: 6px 0 0;
  color: #444;
}

.banner-right {
  display: flex;
  align-items: center;
}

.github-link {
  display: flex;
  align-items: center;
  gap: 8px;
  color: #333;
  text-decoration: none;
  padding: 8px 12px;
  border-radius: 3px;
  transition: background-color 0.2s;
}

.github-link:hover {
  background-color: #ddd;
  color: #000;
}

.github-icon {
  width: 24px;
  height: 24px;
}

.layout {
  display: grid;
  grid-template-columns: 260px 1fr;
}

.nav {
  background: #f5f5f5;
  border-right: 1px solid #c8c8c8;
  padding: 20px;
}

.nav h2 {
  font-size: 1.05rem;
  margin: 0 0 12px;
  border-bottom: 1px solid #c8c8c8;
  padding-bottom: 8px;
}

.nav ul {
  list-style: none;
  padding: 0;
  margin: 0 0 18px;
}

.nav li {
  margin: 0 0 8px;
}

.nav .small {
  font-size: 0.92rem;
  color: #555;
}

.content {
  padding: 24px 28px 36px;
  overflow-x: hidden;
}

.chapter-title {
  margin: 0 0 10px;
  font-size: 1.7rem;
  font-weight: normal;
  border-bottom: 1px solid #d4d4d4;
  padding-bottom: 8px;
}

.chapter-meta {
  margin: 0 0 18px;
  color: #666;
  font-size: 0.95rem;
}

.box {
  border: 1px solid #ddd;
  background: #fbfbfb;
  padding: 16px;
  margin: 16px 0;
  border-radius: 3px;
  box-sizing: border-box;
  width: 100%;
}

.box h3 {
  margin: 0 0 8px;
  font-size: 1.1rem;
}

code,
pre {
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.95rem;
}

pre {
  background: #f4f4f4;
  border: 1px solid #c8c8c8;
  padding: 14px;
  overflow: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0 18px;
  box-sizing: border-box;
  overflow-x: auto;
}

th,
td {
  border: 1px solid #c8c8c8;
  padding: 8px 10px;
  vertical-align: top;
}

th {
  background: #efefef;
  text-align: left;
}

.footer-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  border-top: 1px solid #d4d4d4;
  margin-top: 28px;
  padding-top: 14px;
  font-size: 0.95rem;
}

ul.tight li {
  margin-bottom: 6px;
}

/* Enhanced callout boxes - greyscale */
.note {
  border-left: 4px solid #666;
  background: #f8f8f8;
  padding: 16px;
  margin: 18px 0;
  border-radius: 3px;
  box-sizing: border-box;
  width: 100%;
}

.note strong {
  color: #1a1a1a;
}

.warning {
  border-left: 4px solid #999;
  background: #f5f5f5;
  padding: 16px;
  margin: 18px 0;
  border-radius: 3px;
  box-sizing: border-box;
  width: 100%;
}

.warning strong {
  color: #1a1a1a;
}

.tip {
  border-left: 4px solid #777;
  background: #f9f9f9;
  padding: 16px;
  margin: 18px 0;
  border-radius: 3px;
  box-sizing: border-box;
  width: 100%;
}

.tip strong {
  color: #1a1a1a;
}

/* Diagram styling */
.diagram {
  background: #f9f9f9;
  border: 2px solid #999;
  border-radius: 4px;
  padding: 20px;
  margin: 20px 0;
  font-family: Consolas, "Courier New", monospace;
  font-size: 12px;
  overflow-x: auto;
  line-height: 1.4;
  color: #333;
  text-align: left;
  width: 100%;
  box-sizing: border-box;
  box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.05);
  white-space: pre;
}

/* Section headers with anchors */
h2 {
  margin: 28px 0 14px;
  font-size: 1.6rem;
  font-weight: normal;
  border-bottom: 2px solid #e0e0e0;
  padding-bottom: 8px;
}

h3 {
  margin: 20px 0 12px;
  font-size: 1.25rem;
  font-weight: normal;
}

h4 {
  margin: 16px 0 10px;
  font-size: 1.1rem;
  font-weight: 600;
}

/* Better code styling */
code {
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.93rem;
  background: #f5f5f5;
  padding: 3px 6px;
  border-radius: 3px;
  color: #c33;
}

pre {
  background: #f4f4f4;
  border: 1px solid #ddd;
  border-left: 4px solid #999;
  padding: 16px;
  overflow-x: auto;
  margin: 16px 0;
  line-height: 1.5;
  border-radius: 3px;
  box-sizing: border-box;
  width: 100%;
}

pre code {
  background: none;
  padding: 0;
  color: #333;
}

/* Lists improvements */
ul, ol {
  margin: 14px 0;
  padding-left: 24px;
}

ul li, ol li {
  margin: 8px 0;
}

/* Blockquote styling */
blockquote {
  border-left: 4px solid #aaa;
  color: #555;
  margin: 16px 0;
  padding-left: 20px;
  font-style: italic;
  box-sizing: border-box;
}

/* Example box - greyscale */
.example {
  border: 1px solid #ccc;
  background: #f8f8f8;
  padding: 16px;
  margin: 16px 0;
  border-left: 4px solid #666;
  border-radius: 3px;
  box-sizing: border-box;
  width: 100%;
}

.example strong {
  color: #1a1a1a;
  display: block;
  margin-bottom: 8px;
}

/* Learning outcome list - greyscale */
.learning-outcomes {
  background: #fafafa;
  border-left: 4px solid #777;
  padding: 16px;
  margin: 16px 0;
  border-radius: 3px;
  box-sizing: border-box;
  width: 100%;
}

.learning-outcomes h4 {
  margin: 0 0 10px;
  color: #1a1a1a;
}

.learning-outcomes ul {
  margin: 0;
  padding-left: 24px;
}

.learning-outcomes li {
  margin: 6px 0;
}

@media (max-width: 900px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .nav {
    border-right: 0;
    border-bottom: 1px solid #c8c8c8;
  }
}