/**
 * ScienceDirect-style article page
 * Clean, academic layout with serif typography and clear hierarchy
 */

:root {
  --sd-text: #222;
  --sd-text-secondary: #555;
  --sd-text-muted: #6c757d;
  --sd-border: #dee2e6;
  --sd-bg: #fff;
  --sd-bg-alt: #f8f9fa;
  --sd-accent: #0d4a3b;
  --sd-accent-hover: #0a3d30;
  --sd-link: #0066a1;
  --sd-link-hover: #004d7a;
  --sd-font-serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
  --sd-font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --sd-max-content: 720px;
  --sd-sidebar-width: 280px;
}

.sd-article {
  background: var(--sd-bg);
  color: var(--sd-text);
  font-family: var(--sd-font-serif);
  padding-bottom: 3rem;
}

/* Top bar */
.sd-article-bar {
  background: var(--sd-bg-alt);
  border-bottom: 1px solid var(--sd-border);
  padding: 0.6rem 0;
  position: sticky;
  top: 0;
  z-index: 50;
}

.sd-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

.sd-article-bar .sd-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.sd-breadcrumb {
  font-size: 0.875rem;
  font-family: var(--sd-font-sans);
  color: var(--sd-text-muted);
}

.sd-breadcrumb a {
  color: var(--sd-link);
  text-decoration: none;
}

.sd-breadcrumb a:hover {
  text-decoration: underline;
  color: var(--sd-link-hover);
}

.sd-breadcrumb-sep {
  margin: 0 0.35rem;
  color: var(--sd-border);
}

.sd-breadcrumb-current {
  color: var(--sd-text-secondary);
  max-width: 280px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.sd-toolbar {
  display: flex;
  gap: 0.5rem;
}

.sd-tool-btn {
  font-family: var(--sd-font-sans);
  font-size: 0.8125rem;
  color: var(--sd-text-secondary);
  background: var(--sd-bg);
  border: 1px solid var(--sd-border);
  padding: 0.4rem 0.75rem;
  border-radius: 4px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  transition: background 0.15s, color 0.15s;
}

.sd-tool-btn:hover {
  background: var(--sd-bg-alt);
  color: var(--sd-accent);
  border-color: var(--sd-accent);
}

/* Layout: main + sidebar */
.sd-article-layout {
  display: grid;
  grid-template-columns: 1fr var(--sd-sidebar-width);
  gap: 2.5rem;
  align-items: start;
  padding-top: 2rem;
  padding-bottom: 2rem;
}

.sd-main {
  min-width: 0;
  max-width: 100%;
}

/* Article header */
.sd-article-header {
  margin-bottom: 1.5rem;
}

.sd-article-kicker {
  font-family: var(--sd-font-sans);
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--sd-accent);
  margin: 0 0 0.5rem 0;
}

.sd-article-title {
  font-family: var(--sd-font-serif);
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  font-weight: 700;
  line-height: 1.25;
  color: var(--sd-text);
  margin: 0 0 1rem 0;
  max-width: var(--sd-max-content);
}

.sd-article-meta {
  font-family: var(--sd-font-sans);
  font-size: 0.875rem;
  color: var(--sd-text-muted);
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.sd-meta-item {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.sd-meta-item i {
  font-size: 0.8em;
  opacity: 0.8;
}

/* Featured image */
.sd-article-fig {
  margin: 0 0 1.75rem 0;
  max-width: 100%;
}

.sd-article-fig img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 4px;
  border: 1px solid var(--sd-border);
}

/* Article body – readable column */
.sd-article-body {
  font-size: 1.0625rem;
  line-height: 1.75;
  max-width: var(--sd-max-content);
  color: var(--sd-text);
}

.sd-article-body h1,
.sd-article-body h2,
.sd-article-body h3,
.sd-article-body h4,
.sd-article-body h5,
.sd-article-body h6 {
  font-family: var(--sd-font-serif);
  font-weight: 700;
  margin-top: 1.75rem;
  margin-bottom: 0.6rem;
  line-height: 1.3;
  color: var(--sd-text);
}

.sd-article-body h1 { font-size: 1.5rem; }
.sd-article-body h2 { font-size: 1.35rem; }
.sd-article-body h3 { font-size: 1.2rem; }
.sd-article-body h4 { font-size: 1.1rem; }

.sd-article-body p {
  margin: 0 0 1rem 0;
}

.sd-article-body ul,
.sd-article-body ol {
  margin: 0 0 1rem 0;
  padding-left: 1.5rem;
}

.sd-article-body li {
  margin-bottom: 0.35rem;
}

.sd-article-body blockquote {
  margin: 1.25rem 0;
  padding: 1rem 1.25rem;
  border-left: 4px solid var(--sd-accent);
  background: var(--sd-bg-alt);
  font-style: italic;
  color: var(--sd-text-secondary);
}

.sd-article-body img {
  max-width: 100%;
  height: auto;
  border-radius: 4px;
  margin: 1rem 0;
}

.sd-article-body a {
  color: var(--sd-link);
  text-decoration: none;
}

.sd-article-body a:hover {
  text-decoration: underline;
  color: var(--sd-link-hover);
}

/* Article footer – citation */
.sd-article-footer {
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--sd-border);
  max-width: var(--sd-max-content);
}

.sd-citation {
  font-family: var(--sd-font-sans);
  font-size: 0.875rem;
  color: var(--sd-text-secondary);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.5rem;
}

.sd-citation strong {
  flex: 0 0 auto;
  color: var(--sd-text);
}

#sd-citation-text {
  flex: 1 1 280px;
}

.sd-copy-cite {
  font-size: 0.8125rem;
  color: var(--sd-link);
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.25rem 0.5rem;
  text-decoration: underline;
}

.sd-copy-cite:hover {
  color: var(--sd-link-hover);
}

/* Sidebar */
.sd-sidebar {
  position: sticky;
  top: 4rem;
}

.sd-sidebar-card {
  background: var(--sd-bg-alt);
  border: 1px solid var(--sd-border);
  border-radius: 4px;
  padding: 1.25rem;
  margin-bottom: 1.25rem;
}

.sd-sidebar-title {
  font-family: var(--sd-font-sans);
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--sd-text);
  margin: 0 0 0.75rem 0;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--sd-border);
}

.sd-info-list {
  font-family: var(--sd-font-sans);
  font-size: 0.875rem;
  margin: 0;
}

.sd-info-list dt {
  color: var(--sd-text-muted);
  font-weight: 500;
  margin-top: 0.5rem;
}

.sd-info-list dt:first-child { margin-top: 0; }

.sd-info-list dd {
  margin: 0.15rem 0 0 0;
  color: var(--sd-text);
}

.sd-tools-list,
.sd-quick-links {
  list-style: none;
  margin: 0;
  padding: 0;
}

.sd-tools-list li,
.sd-quick-links li {
  margin-bottom: 0.35rem;
}

.sd-tools-link,
.sd-quick-links a {
  font-family: var(--sd-font-sans);
  font-size: 0.875rem;
  color: var(--sd-link);
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.sd-tools-link:hover,
.sd-quick-links a:hover {
  text-decoration: underline;
  color: var(--sd-link-hover);
}

/* Related articles */
.sd-related {
  background: var(--sd-bg-alt);
  border-top: 1px solid var(--sd-border);
  padding: 2rem 0 3rem;
}

.sd-related-heading {
  font-family: var(--sd-font-sans);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--sd-text);
  margin: 0 0 1.25rem 0;
}

.sd-related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
}

.sd-related-card {
  background: var(--sd-bg);
  border: 1px solid var(--sd-border);
  border-radius: 4px;
  overflow: hidden;
  transition: box-shadow 0.2s, border-color 0.2s;
}

.sd-related-card:hover {
  box-shadow: 0 4px 12px rgba(0,0,0,0.08);
  border-color: var(--sd-accent);
}

.sd-related-link {
  text-decoration: none;
  color: inherit;
  display: block;
}

.sd-related-img {
  aspect-ratio: 16/10;
  overflow: hidden;
  background: var(--sd-bg-alt);
}

.sd-related-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.sd-related-img-placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--sd-text-muted);
  font-size: 1.5rem;
}

.sd-related-content {
  padding: 1rem;
}

.sd-related-date {
  font-family: var(--sd-font-sans);
  font-size: 0.75rem;
  color: var(--sd-text-muted);
  display: block;
  margin-bottom: 0.35rem;
}

.sd-related-title {
  font-family: var(--sd-font-serif);
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.35;
  color: var(--sd-text);
  margin: 0 0 0.5rem 0;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.sd-related-more {
  font-family: var(--sd-font-sans);
  font-size: 0.8125rem;
  color: var(--sd-link);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.sd-related-card:hover .sd-related-more {
  text-decoration: underline;
}

/* Responsive */
@media (max-width: 992px) {
  .sd-article-layout {
    grid-template-columns: 1fr;
  }

  .sd-sidebar {
    position: static;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
  }

  .sd-sidebar-card {
    margin-bottom: 0;
  }
}

@media (max-width: 768px) {
  .sd-article-bar .sd-container {
    flex-direction: column;
    align-items: flex-start;
  }

  .sd-toolbar {
    width: 100%;
    flex-wrap: wrap;
  }

  .sd-article-title {
    font-size: 1.5rem;
  }

  .sd-article-body {
    font-size: 1rem;
  }

  .sd-related-grid {
    grid-template-columns: 1fr;
  }
}

@media print {
  .sd-article-bar,
  .sd-toolbar,
  .sd-sidebar,
  .sd-tool-btn,
  .sd-copy-cite,
  .sd-related {
    display: none !important;
  }

  .sd-article-layout {
    display: block;
  }

  .sd-article-body,
  .sd-article-title,
  .sd-article-footer {
    max-width: 100%;
  }

  .sd-article a[href]::after {
    content: ' (' attr(href) ')';
    font-size: 0.85em;
    color: #666;
  }
}