/* ========================================
   Courses Page Styles
   ======================================== */

/* Filter Bar */
.filter-bar {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  padding: 20px 0;
  position: sticky;
  top: var(--nav-height);
  z-index: 100;
}

.filter-inner {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.filter-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 1px;
  white-space: nowrap;
}

.filter-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  border-radius: 20px;
  padding: 6px 16px;
  font-size: 0.8rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
  font-family: var(--font-body);
}

.filter-btn:hover {
  border-color: var(--accent-yellow);
  color: var(--accent-yellow);
}

.filter-btn.active {
  background: var(--accent-yellow);
  border-color: var(--accent-yellow);
  color: #0d1117;
  font-weight: 600;
}

/* Course Detail TOC */
.course-detail-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 2000;
  background: rgba(0,0,0,0.8);
  backdrop-filter: blur(8px);
  overflow-y: auto;
  padding: 40px 24px;
}

.course-detail-overlay.open {
  display: flex;
  align-items: flex-start;
  justify-content: center;
}

.course-detail-panel {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  max-width: 900px;
  width: 100%;
  overflow: hidden;
  animation: slideUp 0.35s cubic-bezier(0.4,0,0.2,1);
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(40px); }
  to { opacity: 1; transform: translateY(0); }
}

.course-detail-header {
  background: linear-gradient(135deg, var(--bg-card) 0%, var(--bg-primary) 100%);
  border-bottom: 1px solid var(--border-color);
  padding: 40px;
  position: relative;
}

.course-detail-close {
  position: absolute;
  top: 20px;
  right: 20px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 50%;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 1.1rem;
  transition: var(--transition);
}

.course-detail-close:hover {
  border-color: var(--accent-yellow);
  color: var(--accent-yellow);
}

.course-detail-icon {
  font-size: 3rem;
  margin-bottom: 16px;
}

.course-detail-title {
  font-size: 2rem;
  color: var(--text-primary);
  margin-bottom: 10px;
  font-family: var(--font-display);
}

.course-detail-subtitle {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 24px;
}

.course-detail-meta {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

.course-meta-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.course-meta-item strong {
  color: var(--accent-yellow);
}

.course-detail-body {
  padding: 40px;
}

.toc-section {
  margin-bottom: 40px;
}

.toc-section-title {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
  font-family: var(--font-display);
}

.toc-chapters {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toc-chapter {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  overflow: hidden;
  transition: var(--transition);
}

.toc-chapter-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  cursor: pointer;
  user-select: none;
  transition: var(--transition);
}

.toc-chapter-header:hover {
  background: var(--bg-card-hover);
}

.toc-chapter-num {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: rgba(240,180,41,0.1);
  border: 1px solid rgba(240,180,41,0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent-yellow);
  font-family: var(--font-mono);
  flex-shrink: 0;
}

.toc-chapter-name {
  flex: 1;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  font-family: var(--font-display);
}

.toc-chapter-toggle {
  font-size: 0.8rem;
  color: var(--text-muted);
  transition: var(--transition);
}

.toc-chapter.open .toc-chapter-toggle {
  transform: rotate(180deg);
}

.toc-chapter-lessons {
  display: none;
  border-top: 1px solid var(--border-color);
  padding: 8px 0;
}

.toc-chapter.open .toc-chapter-lessons {
  display: block;
}

.toc-lesson {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 20px 10px 62px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  transition: var(--transition);
}

.toc-lesson:hover {
  color: var(--accent-yellow);
  background: rgba(240,180,41,0.03);
}

.toc-lesson-icon {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.course-detail-enroll {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px;
}

.enroll-price-row {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 8px;
}

.enroll-price {
  font-family: var(--font-mono);
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--accent-yellow);
}

.enroll-original {
  font-size: 1.1rem;
  color: var(--text-muted);
  text-decoration: line-through;
  font-family: var(--font-mono);
}

.enroll-discount {
  background: rgba(63,185,80,0.1);
  color: #3fb950;
  border: 1px solid rgba(63,185,80,0.2);
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 700;
}

.enroll-note {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.enroll-btn {
  width: 100%;
  justify-content: center;
  padding: 14px;
  font-size: 1rem;
}

.enroll-features {
  margin-top: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.enroll-feature {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.enroll-feature-icon {
  color: #3fb950;
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  .course-detail-header,
  .course-detail-body {
    padding: 24px 20px;
  }

  .course-detail-title {
    font-size: 1.5rem;
  }

  .filter-bar {
    position: static;
  }

  .course-detail-overlay {
    padding: 20px 12px;
  }
}