/* Theory Header */
.theory-header {
  text-align: center;
  margin-bottom: 2rem;
  padding: 2rem 1rem;
  background: linear-gradient(135deg, var(--brand) 0%, #c41e3a 100%);
  color: blanchedalmond;
  border-radius: 12px;
}

.theory-header h1 {
  margin-bottom: 1rem;
  font-size: 2.5rem;
  font-weight: 700;
  line-height: 1.2;
}

.theory-subtitle {
  font-size: 1.1rem;
  line-height: 1.6;
  opacity: 0.95;
  max-width: 800px;
  margin: 0 auto;
}

/* Navigation */
.theory-nav {
  background: var(--bg-secondary);
  border-radius: 8px;
  padding: 1.5rem;
  margin-bottom: 2rem;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.theory-nav h2 {
  color: var(--brand);
  margin-bottom: 1rem;
  font-size: 1.3rem;
  border-bottom: 2px solid var(--brand);
  padding-bottom: 0.5rem;
}

.theory-nav ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.theory-nav li {
  margin-bottom: 0.5rem;
}

.theory-nav a {
  display: block;
  padding: 0.75rem 1rem;
  color: var(--fg);
  text-decoration: none;
  border-radius: 6px;
  transition: all 0.3s ease;
  font-weight: 500;
}

.theory-nav a:hover {
  background: var(--brand);
  color: white;
  transform: translateX(4px);
}

/* Theory Sections */
.theory-section {
  margin-bottom: 2.5rem;
  scroll-margin-top: 100px;
}

.theory-section h2 {
  color: var(--brand);
  border-bottom: 3px solid var(--brand);
  padding-bottom: 0.75rem;
  margin-bottom: 1.5rem;
  font-size: 1.8rem;
  font-weight: 700;
}

.theory-section h3 {
  color: var(--brand);
  margin: 1.5rem 0 1rem 0;
  font-size: 1.3rem;
  font-weight: 600;
}

.theory-section h4 {
  color: var(--fg);
  margin: 1.2rem 0 0.8rem 0;
  font-size: 1.1rem;
  font-weight: 600;
}

.theory-section ul {
  padding-left: 1.5rem;
  line-height: 1.7;
}

.theory-section li {
  margin-bottom: 0.75rem;
}

.theory-section li ul {
  margin-top: 0.5rem;
  padding-left: 1.2rem;
}

.theory-section li ul li {
  margin-bottom: 0.4rem;
  font-size: 0.95rem;
}

/* Quotes Section */
.quotes-section {
  margin: 2rem 0;
  padding: 1.5rem;
  background: var(--bg-secondary);
  border-radius: 8px;
  border-left: 4px solid var(--brand);
}

.quotes-section h4 {
  color: var(--brand);
  margin-bottom: 1rem;
  font-size: 1.2rem;
}

.quotes-grid {
  display: grid;
  gap: 1rem;
}

.quote-item {
  background: white;
  padding: 1.2rem;
  border-radius: 6px;
  border-left: 3px solid var(--brand);
  margin: 0;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
}

.quote-item p {
  font-style: italic;
  color: var(--fg);
  margin-bottom: 0.75rem;
  line-height: 1.6;
  font-size: 1.05rem;
}

.quote-item cite {
  font-style: normal;
  color: var(--brand);
  font-weight: 600;
  font-size: 0.9rem;
}

.quote-item cite small {
  color: var(--text-muted);
  font-weight: 400;
}

/* Source References */
sup[data-src] {
  color: var(--brand);
  font-weight: 600;
  cursor: pointer;
  padding: 2px 4px;
  border-radius: 3px;
  transition: all 0.2s ease;
}

sup[data-src]:hover {
  background: var(--brand);
  color: white;
}

/* Sources Section */
#source-list {
  margin-top: 3rem;
}

#source-list h2 {
  color: var(--brand);
  border-bottom: 3px solid var(--brand);
  padding-bottom: 0.75rem;
  margin-bottom: 2rem;
}

.sources-grid {
  display: grid;
  gap: 1.5rem;
}

.source-item {
  padding: 1.5rem;
  border-radius: 8px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.source-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.source-item.highlighted {
  background: var(--brand-light);
  border-color: var(--brand);
  animation: highlight-pulse 3s ease-out;
}

@keyframes highlight-pulse {
  0% {
    background: var(--brand-light);
  }
  50% {
    background: var(--brand-lighter);
  }
  100% {
    background: var(--bg-secondary);
  }
}

.source-item h4 {
  color: var(--brand);
  margin-bottom: 1rem;
  font-size: 1.1rem;
  font-weight: 600;
  line-height: 1.3;
}

.source-meta p {
  margin-bottom: 0.5rem;
  font-size: 0.9rem;
  color: var(--fg);
}

.source-desc {
  font-style: italic;
  color: var(--text-muted);
  margin: 0.75rem 0;
  line-height: 1.5;
}

.source-link {
  display: inline-block;
  margin-top: 0.75rem;
  font-size: 0.9rem;
}

/* Conclusion Highlight */
.conclusion-highlight {
  background: linear-gradient(135deg, #f8f9fa 0%, var(--bg-secondary) 100%);
  padding: 1.5rem;
  border-radius: 8px;
  border-left: 4px solid var(--brand);
  margin-top: 1.5rem;
}

.conclusion-highlight h4 {
  color: var(--brand);
  margin-bottom: 0.75rem;
}

/* Action Buttons */
.theory-actions {
  display: flex;
  gap: 1rem;
  margin-top: 3rem;
  padding: 2rem;
  background: var(--bg-secondary);
  border-radius: 8px;
  justify-content: center;
}

.btn.primary {
  background: var(--brand);
  color: white;
}

.btn.primary:hover {
  background: #c41e3a;
}

/* Responsive Design */
@media (max-width: 768px) {
  .theory-header h1 {
    font-size: 2rem;
  }

  .theory-subtitle {
    font-size: 1rem;
  }

  .theory-nav a {
    padding: 0.6rem 0.8rem;
    font-size: 0.9rem;
  }

  .theory-section h2 {
    font-size: 1.5rem;
  }

  .theory-actions {
    flex-direction: column;
    align-items: center;
  }

  .theory-actions .btn {
    width: 100%;
    max-width: 300px;
  }
}

@media (min-width: 769px) {
  .quotes-grid {
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
  }

  .sources-grid {
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  }
}
/* ===== Khối ảnh minh họa trong trang Kiến thức ===== */
.img-block {
  margin-top: 20px;
}

.img-block > h3 {
  margin: 0 0 12px 0;
  font-size: 1.15rem;
  color: var(--brand);
  font-weight: 700;
}

.img-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.img-card {
  margin: 0;
  background: #ffffff;
  border: 1px solid rgba(0, 0, 0, 0.06);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
  transition: transform 160ms ease, box-shadow 160ms ease;
}

.img-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 26px rgba(0, 0, 0, 0.12);
}

.img-card img {
  display: block;
  width: 100%;
  height: 220px;
  object-fit: cover;
  object-position: center center;
  cursor: zoom-in; /* gợi ý có thể bấm để xem lớn */
}

.img-card figcaption {
  padding: 10px 12px;
  font-size: 0.95rem;
  color: var(--fg);
  line-height: 1.5;
}

/* Màn hình vừa: 2 cột */
@media (max-width: 992px) {
  .img-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .img-card img {
    height: 200px;
  }
}

/* Màn hình nhỏ: 1 cột */
@media (max-width: 600px) {
  .img-grid {
    grid-template-columns: 1fr;
  }
  .img-card img {
    height: 220px;
  }
}
/* Nền tối phủ toàn màn hình */
.lightbox-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  padding: 0; /* bỏ padding để ảnh tối đa */
}

.lightbox-backdrop.active {
  display: flex;
}

/* Ảnh phóng to – luôn đầy màn hình mà vẫn giữ tỉ lệ */
.lightbox-img {
  width: 96vw; /* chiếm gần hết chiều ngang */
  height: 92vh; /* chiếm gần hết chiều cao */
  object-fit: contain; /* giữ tỉ lệ, không bị méo, không cắt */
  border-radius: 12px;
  box-shadow: 0 10px 28px rgba(0, 0, 0, 0.35);
  background: #ffffff;
  cursor: zoom-out; /* gợi ý có thể bấm để đóng */
}

/* Nút đóng lớn hơn, dễ bấm */
.lightbox-close {
  position: fixed;
  top: 16px;
  right: 20px;
  background: #ffffff;
  border: 0;
  border-radius: 999px;
  width: 48px;
  height: 48px;
  font-size: 22px;
  line-height: 48px;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}
/* Biến thể nút trắng cho link nguồn */
.btn--white {
  background: #fff !important;
  color: var(--brand) !important;
  border: 2px solid var(--gold) !important;
  text-shadow: none !important;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.12) !important;
}

/* Tắt hiệu ứng “shine” của .btn mặc định */
.btn--white::before {
  display: none !important;
}

/* Hover: đảo màu cho nổi bật */
.btn--white:hover {
  background: var(--brand) !important;
  color: #fff !important;
  border-color: var(--yellow-star) !important;
  transform: translateY(-2px);
}
/* Ảnh minh họa ngay dưới phần intro */
.intro-figure{
  margin: 20px 0 28px;
  border-radius: 14px;
  overflow: hidden;
  background: #fff;
  border: 2px solid var(--gold);
  box-shadow: 0 10px 28px rgba(0,0,0,.12);
}

.intro-figure img{
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  max-height: 650px;             /* giữ trang gọn gàng */
}

.intro-figure figcaption{
  padding: 10px 14px;
  font-size: .95rem;
  color: var(--muted);
  text-align: center;
  background: linear-gradient(180deg,#fff, #fff8dc);
  border-top: 1px solid rgba(0,0,0,.06);
}

/* Mobile tinh gọn */
@media (max-width: 640px){
  .intro-figure img{ max-height: 300px; }
  .intro-figure figcaption{ font-size: .9rem; padding: 8px 12px; }
}