/* ==============================================
   Color theme — override Freelancer/Bootstrap
   ============================================== */
:root {
  --bs-primary: #6366f1;
  --bs-primary-rgb: 99, 102, 241;
  --bs-secondary: #0f172a;
  --bs-secondary-rgb: 15, 23, 42;
  --bs-link-color: #6366f1;
  --bs-link-hover-color: #4f46e5;
}

/* Navbar hover / active link colour */
#mainNav .navbar-nav li.nav-item a.nav-link:hover,
#mainNav .navbar-nav li.nav-item a.nav-link.active {
  color: #a5b4fc !important;
}

#mainNav .navbar-nav > li.nav-item > a.nav-link.active,
#mainNav .navbar-nav > li.nav-item > a.nav-link.active:active,
#mainNav .navbar-nav > li.nav-item > a.nav-link.active:focus,
#mainNav .navbar-nav > li.nav-item > a.nav-link.active:hover {
  background: #6366f1 !important;
  color: #fff !important;
}

/* Masthead hero */
.masthead {
  background-color: #0f172a !important;
}

/* Portfolio caption overlay */
.portfolio .portfolio-item .portfolio-item-caption {
  background-color: rgba(99, 102, 241, 0.9) !important;
}

/* Buttons */
.btn-primary {
  background-color: #6366f1;
  border-color: #6366f1;
}
.btn-primary:hover,
.btn-primary:focus {
  background-color: #4f46e5;
  border-color: #4f46e5;
}
.btn-outline-primary {
  color: #6366f1;
  border-color: #6366f1;
}
.btn-outline-primary:hover {
  background-color: #6366f1;
  border-color: #6366f1;
}

/* Footer */
.footer {
  background-color: #0f172a !important;
}

/* ==============================================
   Paper cards (papers.html)
   ============================================== */
.paper-card {
  border: 1px solid rgba(99, 102, 241, 0.18);
  border-radius: 0.75rem;
  padding: 1.75rem 2rem;
  margin-bottom: 1.75rem;
  background: #fff;
  box-shadow: 0 2px 12px rgba(15, 23, 42, 0.07);
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.paper-card:hover {
  box-shadow: 0 8px 28px rgba(99, 102, 241, 0.14);
  transform: translateY(-3px);
}

.paper-tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  background: rgba(99, 102, 241, 0.1);
  color: #6366f1;
  margin-bottom: 0.9rem;
}

.paper-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: #0f172a;
  margin-bottom: 0.6rem;
}

.paper-card p {
  color: #475569;
  font-size: 0.95rem;
  line-height: 1.6;
  margin-bottom: 1.1rem;
}

/* ==============================================
   Model image gallery (tampering.html)
   ============================================== */
.model-gallery .gallery-item {
  margin-bottom: 1.5rem;
}

.model-gallery figure {
  margin: 0;
  background: #f8fafc;
  border: 1px solid #e2e8f0;
  border-radius: 0.75rem;
  overflow: hidden;
  transition: box-shadow 0.2s ease;
  height: 100%;
}

.model-gallery figure:hover {
  box-shadow: 0 6px 24px rgba(99, 102, 241, 0.14);
}

.model-gallery figure img {
  width: 100%;
  height: auto;
  display: block;
}

.model-gallery figcaption {
  padding: 0.6rem 1rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: #475569;
  text-align: center;
  background: #f1f5f9;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

/* Knowledge code badges */
.knowledge-badge {
  display: inline-block;
  padding: 0.35rem 0.9rem;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin: 0.2rem;
}

.knowledge-badge.at {
  background: rgba(99, 102, 241, 0.1);
  color: #6366f1;
  border: 1px solid rgba(99, 102, 241, 0.25);
}

.knowledge-badge.ab {
  background: rgba(13, 148, 136, 0.1);
  color: #0d9488;
  border: 1px solid rgba(13, 148, 136, 0.25);
}

/* Tampering tables */
.tampering-table {
  font-size: 0.88rem;
}

.tampering-table th {
  background-color: #0f172a;
  color: #e2e8f0;
  font-weight: 600;
  letter-spacing: 0.03em;
}

/* ==============================================
   Feature detail card (display_feature.html)
   ============================================== */
.feature-detail-card {
  border: 1px solid #e2e8f0;
  border-radius: 0.75rem;
  overflow: hidden;
  box-shadow: 0 2px 16px rgba(15, 23, 42, 0.08);
}

.feature-detail-card .card-header-gradient {
  background: linear-gradient(135deg, #6366f1 0%, #4f46e5 100%);
  color: #fff;
  padding: 1.5rem 2rem;
}

.feature-detail-card .card-header-gradient h2 {
  font-size: 1.4rem;
  font-weight: 700;
  margin: 0;
}

.feature-detail-card .card-header-gradient .feature-id {
  font-size: 0.8rem;
  opacity: 0.75;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 0.25rem;
}

.feature-detail-card .card-body-inner {
  padding: 2rem;
}

.feature-detail-card .field-label {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: #94a3b8;
  margin-bottom: 0.25rem;
}

.feature-detail-card .field-value {
  color: #1e293b;
  margin-bottom: 1.5rem;
  line-height: 1.6;
}

/* ==============================================
   Index page
   ============================================== */
.index-text h1 {
  font-size: 1.6rem;
  font-weight: 700;
  color: #0f172a;
  margin-bottom: 1rem;
  font-family: 'Courier New', Courier, monospace;
}

.index-image-wrap {
  border-radius: 0.75rem;
  overflow: hidden;
  box-shadow: 0 8px 32px rgba(15, 23, 42, 0.12);
}

.index-image-wrap img {
  width: 100%;
  height: auto;
  display: block;
}

/* section intro spacing */
.section-intro {
  max-width: 760px;
  margin: 0 auto 2rem auto;
}