/* AI, One Concept at a Time — book theme (layered over the docsify default) */

:root {
  --book-accent: #4c6ef5;
  --book-ink: #24292f;
  --book-muted: #6b7280;
  --book-code-bg: #f4f6fa;
  /* pin the docsify core theme's code variables so code blocks stay light */
  --code-bg: var(--book-code-bg);
  --code-color: var(--book-ink);
  --codeblock-bg: var(--book-code-bg);
  --codeblock-color: var(--book-ink);
}

/* cover page */
.cover {
  text-align: center;
}
.cover .cover-main {
  margin-top: 12vh;
}
.cover h1 {
  font-weight: 700;
  letter-spacing: -0.02em;
}
.cover .link-button,
.cover a.button {
  background: var(--book-accent);
  border-color: var(--book-accent);
  color: #fff;
  padding: 12px 28px;
  border-radius: 8px;
}
/* secondary cover CTA (e.g. the star button) renders as an outlined accent button,
   so the primary "Start reading" stays the visually dominant call to action */
.cover a.button.secondary {
  background: transparent;
  color: var(--book-accent);
}

/* reading column */
.content {
  padding: 20px 52px 80px;
  max-width: 100%;
}
.markdown-section {
  max-width: 720px;
  margin: 0 auto;
  padding: 8px 16px 40px;
  color: var(--book-ink);
  font-size: 16.5px;
  line-height: 1.75;
}
.markdown-section p {
  margin: 0.9em 0;
}
.markdown-section img {
  border-radius: 10px;
  box-shadow: 0 2px 14px rgba(0, 0, 0, 0.08);
  margin: 8px 0;
}
.markdown-section blockquote {
  border-left: 4px solid var(--book-accent);
  background: #f6f8fe;
  border-radius: 0 8px 8px 0;
  padding: 8px 18px;
  color: #3b4252;
}
.markdown-section pre {
  border-radius: 10px;
  background: var(--book-code-bg);
  border: 1px solid #e4e8f0;
  color: var(--book-ink);
  padding: 16px 18px;
  overflow-x: auto;
}
.markdown-section pre code {
  color: inherit;
  background: transparent;
}
.markdown-section code {
  border-radius: 6px;
}
/* blocks with no language get a "markup" corner label from the core theme — drop it */
.markdown-section pre[data-lang='markup']::after {
  content: none;
}
.markdown-section h1,
.markdown-section h2,
.markdown-section h3 {
  line-height: 1.3;
  margin-top: 1.6em;
}
.markdown-section hr {
  border: none;
  border-top: 1px solid #e5e7eb;
  margin: 2em auto;
  width: 60%;
}

/* byline + callouts */
.markdown-section > p em:has(> a) {
  color: var(--book-muted);
}
.markdown-section blockquote p:has(> strong:first-child ~ *) {
  font-size: 0.95em;
}

/* prev / next navigation */
.book-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 48px;
  padding-top: 20px;
  border-top: 1px solid #e5e7eb;
}
.book-nav-link {
  display: flex;
  flex-direction: column;
  gap: 4px;
  max-width: 46%;
  padding: 12px 16px;
  border: 1px solid #e5e7eb;
  border-radius: 10px;
  text-decoration: none;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.book-nav-link:hover {
  border-color: var(--book-accent);
  background: #f6f8fe;
}
.book-nav-link:nth-child(2) {
  text-align: right;
  margin-left: auto;
}
.book-nav-dir {
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--book-muted);
}
.book-nav-label {
  font-size: 14px;
  font-weight: 600;
  color: var(--book-ink);
}
.book-nav-empty {
  flex: 1;
}

/* sidebar */
.sidebar {
  border-right: 1px solid #eef0f3;
}
.sidebar .app-name strong {
  color: var(--book-ink);
}
.sidebar-nav > ul > li > p {
  font-weight: 700;
  margin: 18px 12px 6px;
  color: var(--book-ink);
}
.sidebar .book-nav {
  display: none;
}

/* loading state */
.app-loading {
  display: flex;
  height: 100vh;
  align-items: center;
  justify-content: center;
  color: var(--book-muted);
}

@media (max-width: 768px) {
  .markdown-section {
    padding: 8px 14px 32px;
    font-size: 15.5px;
  }
  .book-nav {
    flex-direction: column;
  }
  .book-nav-link,
  .book-nav-link:nth-child(2) {
    max-width: 100%;
    text-align: left;
    margin-left: 0;
  }
}