.lesson-detail-hero {
  position: relative;
  overflow: hidden;
  padding: 0 0 2.25rem;
  border-bottom: 1px solid var(--border-color);
  background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-tertiary) 100%);
}

.lesson-detail-hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(800px circle at 15% 20%, rgba(99, 102, 241, 0.22), transparent 60%), radial-gradient(700px circle at 85% 10%, rgba(20, 184, 166, 0.18), transparent 55%), radial-gradient(900px circle at 50% 100%, rgba(168, 85, 247, 0.12), transparent 60%);
}

.lesson-detail-hero .container {
  position: relative;
  z-index: 1;
}

.lesson-detail-hero-card {
  margin-top: 1rem;
  padding: clamp(1.25rem, 3vw, 2rem);
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  box-shadow: 0 6px 30px rgba(0, 0, 0, 0.18);
}

[data-bs-theme="light"] .lesson-detail-hero-card {
  background: var(--bg-secondary);
  box-shadow: 0 6px 30px rgba(99, 102, 241, 0.12);
}

.lesson-detail-hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 0.85rem;
  border: 1px solid var(--border-color);
  background: rgba(99, 102, 241, 0.16);
  color: var(--text-primary);
  font-weight: 700;
  font-size: 0.9rem;
}

[data-bs-theme="light"] .lesson-detail-hero-badge {
  background: rgba(79, 70, 229, 0.12);
}

.lesson-detail-title {
  margin: 1rem 0 0.75rem;
  font-weight: 900;
  line-height: 1.2;
  font-size: clamp(1.75rem, 4vw, 3rem);
  color: var(--text-primary);
}

.lesson-detail-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 0.75rem;
}

.lesson-detail-meta-item {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.55rem 0.9rem;
  border: 1px solid var(--border-color);
  background: var(--bg-elevated);
  color: var(--text-secondary);
  font-weight: 700;
  font-size: 0.95rem;
}

[data-bs-theme="light"] .lesson-detail-meta-item {
  background: var(--bg-secondary);
}

.lesson-detail-meta-item i {
  color: var(--secondary-400);
}

[data-bs-theme="light"] .lesson-detail-meta-item i {
  color: var(--secondary-600);
}

.lesson-detail-breadcrumb .breadcrumb {
  margin-bottom: 0;
}

.lesson-detail-content-card {
  margin-top: 1.25rem;
  padding: clamp(1.25rem, 2.5vw, 2rem);
  border: 1px solid var(--border-color);
  border-radius: 1.5rem;
  overflow: hidden;
  background: var(--bg-card);
  box-shadow: 0 6px 28px rgba(0, 0, 0, 0.14);
}

[data-bs-theme="light"] .lesson-detail-content-card {
  background: var(--bg-secondary);
  box-shadow: 0 6px 28px rgba(99, 102, 241, 0.1);
}

 .lesson-body .alert-box {
  border-radius: 1rem;
  padding: 1.1rem 1.15rem;
  margin: 1.25rem 0;
  display: flex;
  gap: 1rem;
  border: 1px solid rgba(148, 163, 184, 0.22);
  background: rgba(148, 163, 184, 0.08);
 }

 .lesson-body .alert-box.tip {
  border-color: rgba(16, 185, 129, 0.32);
  background: rgba(16, 185, 129, 0.1);
 }

 .lesson-body .alert-box.warn {
  border-color: rgba(245, 158, 11, 0.32);
  background: rgba(245, 158, 11, 0.1);
 }

 .lesson-body .alert-icon {
  font-size: 1.35rem;
  flex-shrink: 0;
  margin-top: 0.15rem;
 }

 .lesson-body .alert-box.tip .alert-icon {
  color: rgba(52, 211, 153, 0.98);
 }

 .lesson-body .alert-box.warn .alert-icon {
  color: rgba(251, 191, 36, 0.98);
 }

 .lesson-body .alert-title {
  font-weight: 900;
  margin-bottom: 0.35rem;
  color: var(--text-primary);
}

 .lesson-container {
  max-width: 100%;
 }

 @media (min-width: 576px) {
  .lesson-container { max-width: 540px; }
 }

 @media (min-width: 768px) {
  .lesson-container { max-width: 720px; }
 }

 @media (min-width: 992px) {
  .lesson-container { max-width: 960px; }
 }

 @media (min-width: 1200px) {
  .lesson-container { max-width: 1140px; }
 }

 @media (min-width: 1400px) {
  .lesson-container { max-width: 1320px; }
 }

 .course-detail-hero {
  padding: 1.25rem 0 2.75rem;
 }

 .course-detail-hero-card {
  margin-top: 1.5rem;
  margin-bottom: 1.25rem;
 }

 .lesson-detail-content-card {
  margin-top: 1.75rem;
 }

 .lesson-body {
  line-height: 1.9;
 }

 .lesson-body h2,
 .lesson-body .section-title {
  margin-top: 2cm !important;
  margin-bottom: 1cm !important;
 }

 .lesson-body h2:first-child,
 .lesson-body .section-title:first-child {
  margin-top: 2cm !important;
 }

 .lesson-body h3 {
  margin-top: 2cm !important;
  margin-bottom: 1cm !important;
 }

 .lesson-body p {
  margin-bottom: clamp(1.1rem, 1.8vw, 1.5rem);
 }

 .lesson-body .concept-box,
 .lesson-body .alert-box,
 .lesson-body .example-code-wrapper,
 .lesson-body pre,
 .lesson-body .code-block {
  margin-top: clamp(1.25rem, 2.2vw, 1.75rem);
  margin-bottom: clamp(1.25rem, 2.2vw, 1.75rem);
 }

 .lesson-body ol,
 .lesson-body ul {
  margin-top: clamp(0.9rem, 1.5vw, 1.15rem);
  margin-bottom: clamp(1.25rem, 2vw, 1.75rem);
 }

 .lesson-body {
  --lesson-space-xs: clamp(0.5rem, 1vw, 0.75rem);
  --lesson-space-sm: clamp(0.85rem, 1.4vw, 1.15rem);
  --lesson-space-md: clamp(1.25rem, 2.1vw, 1.75rem);
  --lesson-space-lg: clamp(1.75rem, 2.8vw, 2.35rem);
  --lesson-space-xl: clamp(2.25rem, 3.6vw, 3.25rem);
 }

 .lesson-body > h2.section-title:first-child,
 .lesson-body > h2:first-child {
  margin-top: var(--lesson-space-xl) !important;
 }

 .lesson-body :is(h2.section-title, h2) {
  scroll-margin-top: 6rem;
 }

 .lesson-body :is(h2.section-title, h2) + :is(.concept-box, .alert-box, p, ol, ul, pre, .code-block) {
  margin-top: var(--lesson-space-sm) !important;
 }

 .lesson-body .example-code-wrapper {
  margin-top: var(--lesson-space-lg) !important;
  margin-bottom: var(--lesson-space-md) !important;
 }

 .lesson-body .alert-box {
  margin-top: var(--lesson-space-md) !important;
  margin-bottom: var(--lesson-space-md) !important;
 }