/* Smart Social Contracts — minimal consistent theme */

:root {
  --bg-color: #faf9f7;
  --text-color: #333333;
  --heading-color: #1a1a1a;
  --muted-color: #666666;
  --accent-color: #4e6272;
  --border-color: #d8d6d2;
  --surface-color: #f0efeb;
  --nav-bg: #f5f4f1;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --heading-color: #f5f5f5;
    --muted-color: #a0a0a0;
    --accent-color: #8a9aaa;
    --border-color: #404040;
    --surface-color: #2a2a2a;
    --nav-bg: #222222;
  }
}

* { box-sizing: border-box; }

html {
  font-size: 18px;
  scroll-behavior: smooth;
  overflow-x: hidden;
}

body {
  overflow-x: hidden;
  font-family: var(--font);
  line-height: 1.75;
  margin: 0;
  padding: 0;
  background-color: var(--bg-color);
  color: var(--text-color);
}

html:lang(zh) body {
  font-family: var(--font), "PingFang SC", "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

.container {
  max-width: 50em;
  margin: 0 auto;
  padding: 1rem;
}

.top-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: var(--nav-bg);
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
  transition: transform 0.3s ease;
}

.top-bar.hidden { transform: translateY(-100%); }

.top-bar-spacer { height: 54px; }

.top-bar .title-small {
  font-weight: 600;
  font-size: 1rem;
  color: var(--heading-color);
  text-decoration: none;
  white-space: nowrap;
}

.top-bar .title-small:hover {
  text-decoration: underline;
}

.lang-selector select {
  padding: 0.45rem 0.75rem;
  font-size: 0.95rem;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  background: var(--bg-color);
  color: var(--text-color);
  cursor: pointer;
  font-family: var(--font);
}

.book-header {
  text-align: center;
  padding: 2rem 0 1rem;
  margin-bottom: 1.5rem;
}

.book-header h1 {
  font-size: 2rem;
  font-weight: 600;
  margin: 0 0 0.5rem 0;
  color: var(--heading-color);
}

.book-header .subtitle {
  font-size: 1.05rem;
  color: var(--muted-color);
  margin: 0 0 0.75rem 0;
  line-height: 1.5;
}

.draft-label {
  display: inline-block;
  border: 1px solid var(--border-color);
  color: var(--muted-color);
  padding: 0.1rem 0.4rem;
  border-radius: 3px;
  font-weight: 600;
  font-size: 0.7rem;
  letter-spacing: 0.05em;
  margin-right: 0.35rem;
}


.draft-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: center;
  margin: 0 0 2.5rem;
}

.draft-btn {
  flex: 1 1 0;
  min-width: 7rem;
  max-width: 12rem;
  padding: 0.75rem 1rem;
  text-align: center;
  font-size: 0.95rem;
  font-weight: 500;
  text-decoration: none;
  color: var(--text-color);
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: 4px;
}

a.draft-btn:hover {
  border-color: var(--accent-color);
  color: var(--heading-color);
}

a.draft-btn.active {
  background: var(--heading-color);
  color: var(--bg-color);
  border-color: var(--heading-color);
}

.draft-btn.disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.toc-container {
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  margin-bottom: 2rem;
  overflow: hidden;
}

.toc-header {
  padding: 0.85rem 1.25rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  font-size: 0.95rem;
  user-select: none;
}

.toc-header:hover { background: var(--border-color); }

.toc-toggle {
  font-size: 1.1rem;
  line-height: 1;
  color: var(--muted-color);
}

.toc-container.collapsed .toc-toggle::before { content: "+"; }
.toc-container:not(.collapsed) .toc-toggle::before { content: "−"; }

.toc-content {
  padding: 0 1.25rem 1rem;
  max-height: 2000px;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
}

.toc-container.collapsed .toc-content {
  max-height: 0;
  padding-top: 0;
  padding-bottom: 0;
}

.toc-content ul,
#TOC ul { list-style: none; padding-left: 1rem; margin: 0.5rem 0; }

.toc-content > ul,
#TOC > ul { padding-left: 0; }

.toc-content li,
#TOC li { margin: 0.35rem 0; }

.toc-content a,
#TOC a {
  color: var(--text-color);
  text-decoration: none;
}

.toc-content a:hover,
#TOC a:hover { text-decoration: underline; }

.content h1, .content h2, .content h3, .content h4, .content h5, .content h6,
main h1, main h2, main h3, main h4, main h5, main h6 {
  color: var(--heading-color);
  margin-top: 2rem;
  margin-bottom: 0.75rem;
  line-height: 1.3;
  font-weight: 600;
}

.content h1, main h1 {
  font-size: 1.75rem;
  border-bottom: 1px solid var(--accent-color);
  padding-bottom: 0.4rem;
}

.content h2, main h2 {
  font-size: 1.4rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.25rem;
}

.content h3, main h3 { font-size: 1.2rem; }
.content h4, main h4 { font-size: 1.05rem; }

.content a, main a {
  color: var(--text-color);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.content p, main p { margin: 1.1rem 0; }

.content ul, .content ol, main ul, main ol { padding-left: 1.5rem; }
.content li, main li { margin: 0.5rem 0; }

.content blockquote, main blockquote {
  margin: 1.25rem 0;
  padding: 0.75rem 1.25rem;
  border-left: 3px solid var(--accent-color);
  background: var(--surface-color);
  color: var(--muted-color);
}

.content code, main code {
  font-family: var(--font);
  font-size: 0.9em;
  background: var(--surface-color);
  padding: 0.15em 0.35em;
  border-radius: 3px;
}

.content pre, main pre {
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  padding: 1rem;
  overflow-x: auto;
  border-radius: 4px;
}

.content pre code, main pre code { padding: 0; background: none; border: none; }

.content table, main table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.25rem 0;
  font-size: 0.95rem;
}

.content th, .content td, main th, main td {
  border: 1px solid var(--border-color);
  padding: 0.6rem 0.75rem;
  text-align: left;
}

.content th, main th { background: var(--surface-color); font-weight: 600; }

.content hr, main hr {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 2rem 0;
}

.content img, main img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 1.25rem auto;
}

.text-btn {
  font-family: var(--font);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-color);
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  cursor: pointer;
  padding: 0.35rem 0.65rem;
}

.text-btn:hover {
  border-color: var(--accent-color);
  color: var(--heading-color);
}

.back-to-top {
  position: fixed;
  bottom: 1.25rem;
  right: 1.25rem;
  z-index: 1000;
  text-decoration: none;
  opacity: 0.85;
}

.back-to-top:hover { opacity: 1; }

.menu-btn { display: none; }

.mobile-menu-fixed {
  display: none;
  position: fixed;
  bottom: 1.25rem;
  left: 1rem;
  z-index: 1500;
}

.mobile-sidebar {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 85%;
  max-width: 320px;
  height: 100%;
  background: var(--bg-color);
  z-index: 2000;
  transform: translateX(-100%);
  transition: transform 0.3s ease;
  overflow-y: auto;
  border-right: 1px solid var(--border-color);
}

.mobile-sidebar.open { transform: translateX(0); }

.mobile-sidebar-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  background: var(--bg-color);
}

.mobile-sidebar-header h3 {
  margin: 0;
  font-size: 1rem;
  font-weight: 600;
  color: var(--heading-color);
}

.mobile-sidebar-content { padding: 1rem; }

.mobile-sidebar-content ul { list-style: none; padding-left: 1rem; margin: 0.5rem 0; }
.mobile-sidebar-content > ul { padding-left: 0; }
.mobile-sidebar-content li { margin: 0.5rem 0; }

.mobile-sidebar-content a {
  color: var(--text-color);
  text-decoration: none;
}

.mobile-sidebar-content a:hover { text-decoration: underline; }

.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 1999;
}

.sidebar-overlay.open { display: block; }

footer {
  margin-top: 3rem;
  padding: 2rem 0 1rem;
  text-align: center;
  color: var(--muted-color);
  font-size: 0.85rem;
  line-height: 1.6;
}

footer p {
  margin: 0.5rem 0;
}

footer .build-info {
  color: var(--muted-color);
}

footer a {
  color: var(--text-color);
  text-decoration: underline;
  text-underline-offset: 2px;
}

footer .living-doc-notice {
  max-width: 36em;
  margin-left: auto;
  margin-right: auto;
}

@media (max-width: 768px) {
  .container { padding: 0.75rem; }
  .top-bar .title-small { display: none; }
  .draft-buttons { gap: 0.5rem; }
  .draft-btn {
    min-width: calc(50% - 0.5rem);
    max-width: none;
    font-size: 0.9rem;
    padding: 0.65rem 0.5rem;
  }
  .book-header h1 { font-size: 1.65rem; }
  .content h1, main h1 { font-size: 1.5rem; }
  .content h2, main h2 { font-size: 1.25rem; }
  body.has-toc .menu-btn { display: inline-block; }
  body.has-toc .mobile-sidebar { display: block; }
  body.has-toc .toc-container { display: none; }
  body.has-toc .mobile-menu-fixed { display: inline-block; }
}

@media (max-width: 480px) {
  html { font-size: 17px; }
  .book-header { padding: 1.5rem 0; }
}