:root {
  --rs-bg: #111827;
  --rs-bg-card: #1e293b;
  --rs-bg-card-hover: #243044;
  --rs-accent: #3b82f6;
  --rs-accent-hover: #60a5fa;
  --rs-text: #f1f5f9;
  --rs-text-secondary: #94a3b8;
  --rs-text-muted: #64748b;
  --rs-border: #334155;
  --rs-radius: 10px;
  --rs-font-display: 'Space Grotesk', sans-serif;
  --rs-font-body: 'Inter', sans-serif;
}

.navbar-default {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 9000;
  transform: translateY(-100%);
  opacity: 0;
  transition: transform 0.35s ease, opacity 0.35s ease;
  background: var(--rs-bg) !important;
  border-bottom: 1px solid var(--rs-border) !important;
  box-shadow: 0 2px 16px rgba(0, 0, 0, 0.4);
}

.navbar-default.navbar-visible {
  transform: translateY(0);
  opacity: 1;
}

.navbar-default .navbar-brand {
  color: var(--rs-text) !important;
  font-family: var(--rs-font-display);
  font-size: 14px !important;
  letter-spacing: 2px !important;
}

.navbar-default .navbar-nav li a {
  color: var(--rs-text-secondary) !important;
  font-family: var(--rs-font-body);
}

.navbar-default .navbar-nav li a:hover,
.navbar-default .navbar-nav .active > a {
  color: var(--rs-accent) !important;
}

html { scroll-behavior: smooth; }

.main-home { height: 50vh !important; }
.main-home .overlay { height: 50vh !important; }
#particles-js { height: 50vh !important; }


/* ---- Research Section (index.html) ---- */

.research-section {
  background: var(--rs-bg);
  padding: 5rem 0 6rem;
  font-family: var(--rs-font-body);
}

.research-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.research-section-header {
  text-align: center;
  margin-bottom: 4rem;
}

.research-section-title {
  font-family: var(--rs-font-display);
  color: var(--rs-text);
  font-size: 2.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 1rem;
  padding: 0;
}

.research-section-subtitle {
  color: var(--rs-text-secondary);
  font-size: 1.2rem;
  line-height: 1.6;
  max-width: 700px;
  margin: 0 auto;
  font-weight: 400;
}

.research-list {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.research-item {
  display: flex;
  gap: 3rem;
  align-items: flex-start;
  padding: 2.5rem;
  border-radius: var(--rs-radius);
  background: var(--rs-bg-card);
  border: 1px solid var(--rs-border);
  position: relative;
  transition: border-color 0.3s, background 0.3s, box-shadow 0.3s;
}

.research-item:nth-child(even) {
  flex-direction: row-reverse;
}

.research-item:hover {
  border-color: var(--rs-accent);
  background: var(--rs-bg-card-hover);
  box-shadow: 0 4px 24px rgba(59, 130, 246, 0.08);
}

.research-item-title a {
  color: var(--rs-text) !important;
  text-decoration: none !important;
}

.research-item-title a:hover {
  color: var(--rs-accent) !important;
}

.research-item-image {
  flex: 0 0 360px;
  height: 260px;
  border-radius: 8px;
  overflow: hidden;
}

.research-item-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}

.research-item:hover .research-item-image img {
  transform: scale(1.03);
}

.img-placeholder {
  width: 100%;
  height: 100%;
}

.img-placeholder-1 { background: linear-gradient(135deg, #1e3a5f 0%, #2563eb 50%, #1e40af 100%); }
.img-placeholder-2 { background: linear-gradient(135deg, #1a3a3a 0%, #0d9488 50%, #115e59 100%); }
.img-placeholder-3 { background: linear-gradient(135deg, #3b1a5f 0%, #7c3aed 50%, #5b21b6 100%); }
.img-placeholder-4 { background: linear-gradient(135deg, #3b2a1a 0%, #d97706 50%, #92400e 100%); }

.research-item-content {
  flex: 1;
  min-width: 0;
}

.research-tag {
  display: inline-block;
  font-family: var(--rs-font-body);
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  line-height: 1;
  color: var(--rs-accent);
  background: rgba(59, 130, 246, 0.1);
  padding: 0.3rem 0.75rem;
  border-radius: 4px;
  margin-bottom: 0.85rem;
}

.research-item-title {
  font-family: var(--rs-font-display);
  font-size: 1.65rem;
  font-weight: 600;
  line-height: 1.35;
  margin: 0 0 0.6rem;
  padding: 0;
  color: var(--rs-text);
}

.research-authors {
  color: var(--rs-text-muted) !important;
  font-size: 1.05rem !important;
  font-weight: 400 !important;
  margin: 0 0 1rem;
  line-height: 1.5;
}

.research-summary {
  color: var(--rs-text-secondary) !important;
  font-size: 1.1rem !important;
  font-weight: 400 !important;
  line-height: 1.75 !important;
  margin: 0 0 1.5rem;
}

.research-links {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.research-link {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 1rem;
  font-weight: 500;
  color: var(--rs-accent) !important;
  text-decoration: none !important;
  padding: 0.4rem 0.85rem;
  border-radius: 5px;
  border: 1px solid var(--rs-border);
  transition: border-color 0.2s, background 0.2s, color 0.2s;
  font-family: var(--rs-font-body);
}

.research-link:hover {
  border-color: var(--rs-accent);
  background: rgba(59, 130, 246, 0.15);
  color: var(--rs-accent-hover) !important;
}

.research-read-more {
  display: none;
}


/* ---- Footer ---- */

.site-footer {
  background: var(--rs-bg);
  border-top: 1px solid var(--rs-border);
  padding: 2rem 0;
  text-align: center;
  font-family: var(--rs-font-body);
}

.site-footer p {
  color: var(--rs-text-muted) !important;
  font-size: 0.85rem !important;
  margin: 0;
}


/* ---- Detail Page ---- */

.detail-page {
  background: var(--rs-bg);
  min-height: 100vh;
  font-family: var(--rs-font-body);
  color: var(--rs-text-secondary);
  margin: 0;
}

.detail-nav {
  padding: 1.5rem 2rem;
  max-width: 900px;
  margin: 0 auto;
}

.detail-back {
  color: var(--rs-text-muted);
  text-decoration: none;
  font-size: 1rem;
  transition: color 0.2s;
}

.detail-back:hover {
  color: var(--rs-accent);
}

.detail-header {
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem 2rem 3rem;
}

.detail-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.detail-meta .research-tag {
  margin-bottom: 0;
}

.detail-year {
  font-size: 0.8rem;
  color: var(--rs-text-muted);
  font-weight: 500;
  line-height: 1;
  padding: 0.3rem 0;
}

.detail-header h1 {
  font-family: var(--rs-font-display);
  color: var(--rs-text);
  font-size: 2.75rem;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 1rem;
  padding: 0;
}

.detail-authors {
  color: var(--rs-text-secondary);
  font-size: 1.1rem;
  line-height: 1.6;
  margin: 0 0 1.5rem;
}

.detail-links {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.detail-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--rs-accent);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  border: 1px solid var(--rs-border);
  transition: border-color 0.2s, background 0.2s;
}

.detail-link:hover {
  border-color: var(--rs-accent);
  background: rgba(59, 130, 246, 0.15);
}

.detail-hero-image {
  max-width: 900px;
  margin: 0 auto 3rem;
  padding: 0 2rem;
}

.detail-hero-image img,
.detail-hero-image .img-placeholder {
  width: 100%;
  height: auto;
  border-radius: var(--rs-radius);
  object-fit: contain;
  background: #fff;
}

.detail-hero-image .img-placeholder {
  height: 400px;
}

.detail-body {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 2rem 4rem;
}

.detail-body h2 {
  font-family: var(--rs-font-display);
  color: var(--rs-text);
  font-size: 1.75rem;
  font-weight: 600;
  margin: 3rem 0 1rem;
  padding: 0;
}

.detail-body h2:first-child {
  margin-top: 0;
}

.detail-body p {
  color: var(--rs-text-secondary);
  font-size: 1.1rem;
  line-height: 1.8;
  margin: 0 0 1.25rem;
  font-weight: 400;
}

.results-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0 2rem;
  font-size: 1rem;
}

.results-table thead th {
  background: var(--rs-bg-card);
  color: var(--rs-text);
  font-weight: 600;
  text-align: left;
  padding: 0.75rem 1rem;
  border-bottom: 2px solid var(--rs-border);
}

.results-table tbody td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid var(--rs-border);
  color: var(--rs-text-secondary);
}

.results-table tbody tr:hover {
  background: var(--rs-bg-card);
}

.figure-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin: 2rem 0;
}

.figure-item {
  border-radius: 8px;
  overflow: hidden;
}

.figure-item img,
.figure-item .img-placeholder {
  width: 100%;
  height: auto;
  object-fit: contain;
  background: #fff;
}

.figure-item .img-placeholder {
  height: 200px;
}

.figure-caption {
  font-size: 0.8rem;
  color: var(--rs-text-muted);
  padding: 0.5rem 0;
  text-align: center;
}

.citation-block {
  background: var(--rs-bg-card);
  border: 1px solid var(--rs-border);
  border-radius: 8px;
  padding: 1.25rem;
  margin: 2rem 0;
  font-family: 'Courier New', monospace;
  font-size: 0.8rem;
  line-height: 1.6;
  color: var(--rs-text-muted);
  overflow-x: auto;
  white-space: pre-wrap;
}

.detail-footer {
  border-top: 1px solid var(--rs-border);
  padding: 2rem;
  text-align: center;
}

.detail-footer p {
  color: var(--rs-text-muted);
  font-size: 0.85rem;
  margin: 0;
}


/* ---- Responsive ---- */

@media (max-width: 768px) {
  .research-section {
    padding: 3rem 0 4rem;
  }

  .research-section-title {
    font-size: 1.75rem;
  }

  .research-section-header {
    margin-bottom: 2.5rem;
  }

  .research-item,
  .research-item:nth-child(even) {
    flex-direction: column;
    padding: 1.25rem;
  }

  .research-item-image {
    flex: none;
    width: 100%;
    height: 180px;
  }

  .research-item-title {
    font-size: 1.15rem;
  }

  .research-read-more {
    display: none;
  }

  .detail-header h1 {
    font-size: 1.75rem;
  }

  .detail-hero-image img,
  .detail-hero-image .img-placeholder {
    height: 250px;
  }

  .figure-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .research-container {
    padding: 0 1rem;
  }

  .research-section-title {
    font-size: 1.5rem;
  }

  .research-item {
    gap: 1.5rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .research-item,
  .research-item-image img,
  .research-read-more,
  .research-link,
  .detail-link,
  .detail-back {
    transition: none;
  }

  .research-item:hover .research-item-image img {
    transform: none;
  }
}