.loading-state { text-align: center; padding: 80px; color: #94a3b8; }
.course-hero { background: linear-gradient(135deg, #0f172a, #1e293b); color: #fff; padding: 60px 0; }
.course-hero .container { display: grid; grid-template-columns: 1fr 380px; gap: 40px; }
.course-hero h1 { font-size: 2.3rem; margin: 10px 0 15px; line-height: 1.2; }
.course-hero .short-desc { font-size: 1.1rem; opacity: 0.9; margin-bottom: 20px; }
.course-meta { display: flex; flex-wrap: wrap; gap: 20px; font-size: 0.95rem; opacity: 0.9; }
.course-meta span { display: flex; align-items: center; gap: 6px; }
.method-badge { display: inline-block; background: #f97316; color: #fff; padding: 4px 12px; border-radius: 6px; font-weight: 600; font-size: 0.9rem; }
.level-badge { display: inline-block; background: rgba(255,255,255,0.15); padding: 4px 12px; border-radius: 6px; font-size: 0.9rem; margin-left: 8px; }
.enroll-card { background: #fff; color: #1e293b; border-radius: 12px; padding: 24px; box-shadow: 0 8px 24px rgba(0,0,0,0.15); position: sticky; top: 80px; align-self: flex-start; }
.enroll-card .price { font-size: 2rem; font-weight: 700; color: #f97316; margin: 0 0 20px; }
.enroll-card .btn-enroll { width: 100%; padding: 12px; background: #f97316; color: #fff; border: 0; border-radius: 8px; font-size: 1rem; font-weight: 600; cursor: pointer; margin-bottom: 12px; }
.enroll-card .btn-enroll:hover { background: #ea580c; }
.enroll-card .btn-secondary { width: 100%; padding: 12px; background: #fff; color: #1e293b; border: 1px solid #e2e8f0; border-radius: 8px; font-size: 1rem; font-weight: 600; cursor: pointer; }
.enroll-card ul { list-style: none; padding: 0; margin: 16px 0 0; }
.enroll-card ul li { padding: 8px 0; font-size: 0.95rem; color: #475569; border-bottom: 1px solid #f1f5f9; }
.enroll-card ul li:last-child { border: 0; }
.course-body { padding: 40px 0 60px; }
.course-body .container { display: grid; grid-template-columns: 1fr 380px; gap: 40px; }
.course-section { background: #fff; border-radius: 12px; padding: 30px; margin-bottom: 24px; box-shadow: 0 2px 8px rgba(0,0,0,0.04); }
.course-section h2 { margin: 0 0 16px; font-size: 1.4rem; color: #1e293b; }
.course-section p { color: #475569; line-height: 1.7; }
.curriculum-section { border: 1px solid #e2e8f0; border-radius: 8px; margin-bottom: 12px; overflow: hidden; }
.curriculum-section .section-header { padding: 14px 18px; background: #f8fafc; display: flex; justify-content: space-between; align-items: center; cursor: pointer; user-select: none; }
.curriculum-section .section-header:hover { background: #f1f5f9; }
.curriculum-section h3 { margin: 0; font-size: 1rem; color: #1e293b; }
.curriculum-section .section-meta { font-size: 0.85rem; color: #64748b; }
.curriculum-section .lesson-list { display: none; padding: 0; margin: 0; list-style: none; }
.curriculum-section.expanded .lesson-list { display: block; }
.curriculum-section .lesson-item { padding: 12px 18px; border-top: 1px solid #e2e8f0; display: flex; justify-content: space-between; align-items: center; font-size: 0.95rem; }
.lesson-icon { width: 20px; color: #94a3b8; margin-right: 10px; }
.free-badge { display: inline-block; background: #10b981; color: #fff; padding: 2px 8px; border-radius: 4px; font-size: 0.75rem; margin-left: 8px; }
.lock-badge { color: #94a3b8; font-size: 0.85rem; }
.lesson-duration { color: #64748b; font-size: 0.85rem; }
@media (max-width: 900px) {
  .course-hero .container, .course-body .container { grid-template-columns: 1fr; }
  .enroll-card { position: static; }
}

/* ============================================ */
/* COURSE PAGE ENHANCEMENT LAYER (Udacity-inspired) */
/* Purely additive - safe to remove if needed   */
/* ============================================ */

.course-hero { position: relative; overflow: hidden; }
.course-hero::before { content: ''; position: absolute; inset: 0; pointer-events: none; background: radial-gradient(800px 400px at 80% 20%, rgba(249,115,22,0.14), transparent 60%), radial-gradient(700px 380px at 20% 80%, rgba(42,92,142,0.20), transparent 55%); z-index: 0; }
.course-hero > * { position: relative; z-index: 1; }
.course-hero h1 { font-size: clamp(32px, 4vw, 52px); font-weight: 800; letter-spacing: -0.02em; line-height: 1.1; }
.short-desc { font-size: clamp(15px, 1.2vw, 18px); line-height: 1.6; opacity: 0.92; }
.method-badge, .level-badge { display: inline-block; padding: 4px 12px; border-radius: 100px; font-size: 12px; font-weight: 700; letter-spacing: 0.04em; text-transform: uppercase; transition: transform 160ms ease; }
.method-badge:hover, .level-badge:hover { transform: translateY(-1px); }

.enroll-card { transition: transform 240ms cubic-bezier(.2,.8,.2,1), box-shadow 240ms ease, border-color 240ms ease; border-radius: 16px; }
.enroll-card:hover { transform: translateY(-3px); box-shadow: 0 18px 40px rgba(15,23,42,0.14); border-color: rgba(249,115,22,0.35); }
.price { letter-spacing: -0.02em; font-weight: 800; }
.btn-enroll { transition: transform 180ms ease, box-shadow 180ms ease, background 180ms ease; box-shadow: 0 4px 14px rgba(249,115,22,0.35); border-radius: 10px; font-weight: 700; }
.btn-enroll:hover { transform: translateY(-2px); box-shadow: 0 10px 24px rgba(249,115,22,0.45); }

.curriculum-section { border-radius: 14px; overflow: hidden; transition: box-shadow 200ms ease; }
.curriculum-section:hover { box-shadow: 0 4px 14px rgba(15,23,42,0.06); }
.section-header { transition: background 180ms ease; cursor: pointer; }
.section-header:hover { background: rgba(249,115,22,0.04); }

.lesson-item { transition: background 160ms ease, transform 160ms ease; border-radius: 8px; }
.lesson-item:hover { background: rgba(21,102,192,0.05); transform: translateX(2px); }
.lesson-icon { transition: transform 200ms ease; }
.lesson-item:hover .lesson-icon { transform: scale(1.1); }
.free-badge { background: linear-gradient(135deg, #16a34a, #22c55e); color: #fff; padding: 2px 8px; border-radius: 100px; font-size: 11px; font-weight: 700; letter-spacing: 0.04em; box-shadow: 0 2px 6px rgba(22,163,74,0.3); }
.lock-badge { opacity: 0.55; }