.lesson-page{min-height:100vh;padding-top:80px}.lesson-progress-bar{position:fixed;top:0;left:0;right:0;height:4px;background:#ffffff4d;z-index:9999}.lesson-progress-fill{height:100%;background:linear-gradient(90deg,#10b981,#3b82f6);transition:width .3s ease}.lesson-sidebar{background:#fff;border-radius:16px;box-shadow:0 10px 40px #0000001a;overflow:hidden}.lesson-sidebar-header{background:linear-gradient(135deg,#667eea,#006c35);color:#fff;padding:1.5rem;border:none}.lesson-sidebar-body{max-height:calc(100vh - 200px);overflow-y:auto}.lesson-sidebar-body::-webkit-scrollbar{width:6px}.lesson-sidebar-body::-webkit-scrollbar-track{background:#f1f1f1}.lesson-sidebar-body::-webkit-scrollbar-thumb{background:#667eea;border-radius:3px}.module-section-header{background:#f8fafc;padding:1rem 1.25rem;border-bottom:2px solid #e2e8f0;cursor:pointer;transition:all .3s}.module-section-header:hover{background:#f1f5f9}.lesson-item{padding:.875rem 1.25rem;border-bottom:1px solid #f1f5f9;transition:all .3s;text-decoration:none;color:inherit;display:block}.lesson-item:hover{background:#f8fafc;transform:translate(4px)}.lesson-item.active{background:linear-gradient(90deg,#667eea1a,#764ba21a);border-left:4px solid #667eea}.lesson-item.disabled{opacity:.5;pointer-events:none}.lesson-main-content{background:#fff;border-radius:16px;box-shadow:0 10px 40px #0000001a;overflow:hidden}.lesson-header{background:linear-gradient(135deg,#667eea,#006c35);color:#fff;padding:2rem}.lesson-breadcrumb{background:#fff3;padding:.75rem 1.25rem;border-radius:8px;margin-bottom:1.5rem}.lesson-breadcrumb .breadcrumb{margin:0}.lesson-breadcrumb .breadcrumb-item a{color:#fff;text-decoration:none}.lesson-breadcrumb .breadcrumb-item.active{color:#fffc}.lesson-breadcrumb .breadcrumb-item+.breadcrumb-item:before{color:#fff9}.lesson-title{font-size:2rem;font-weight:700;margin-bottom:1rem;line-height:1.3}.lesson-meta{display:flex;flex-wrap:wrap;gap:1.5rem;opacity:.95}.lesson-meta-item{display:flex;align-items:center;gap:.5rem}.lesson-body{padding:2rem}.video-wrapper{position:relative;border-radius:12px;overflow:hidden;box-shadow:0 8px 24px #0000001f;margin-bottom:2rem}.video-wrapper video{width:100%;display:block}.completion-badge{position:absolute;top:1rem;right:1rem;background:#10b981f2;color:#fff;padding:.5rem 1rem;border-radius:24px;font-weight:600;font-size:.875rem;display:flex;align-items:center;gap:.5rem;box-shadow:0 4px 12px #10b9814d}.lesson-content-area{background:#f9fafb;padding:2rem;border-radius:12px;margin-bottom:2rem}.lesson-content{font-size:1.125rem;line-height:1.8;color:#374151}.lesson-content h1,.lesson-content h2,.lesson-content h3{color:#1f2937;margin-top:2rem;margin-bottom:1rem}.lesson-content img{max-width:100%;border-radius:8px;margin:1.5rem 0}.lesson-content pre{background:#1f2937;color:#f9fafb;padding:1.5rem;border-radius:8px;overflow-x:auto}.lesson-content code{background:#e5e7eb;padding:.25rem .5rem;border-radius:4px;font-size:.9em}.lesson-actions{padding:1.5rem 2rem;background:#f9fafb;border-top:1px solid #e5e7eb}.mark-complete-btn{background:linear-gradient(135deg,#10b981,#059669);color:#fff;border:none;padding:.875rem 2rem;border-radius:8px;font-weight:600;font-size:1rem;transition:all .3s;box-shadow:0 4px 12px #10b9814d}.mark-complete-btn:hover{transform:translateY(-2px);box-shadow:0 6px 20px #10b98166}.lesson-navigation{grid-template-columns:1fr 1fr;gap:1rem;margin-top:2rem}.nav-btn{padding:.5rem;border-radius:8px;border:2px solid #e5e7eb;background:#fff;text-decoration:none;color:#374151;transition:all .3s;display:flex;align-items:center;justify-content:center;gap:.5rem;font-weight:600}.nav-btn:hover{border-color:#667eea;color:#667eea;transform:translateY(-2px);box-shadow:0 4px 12px #667eea33}.nav-btn-primary{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;border-color:transparent}.nav-btn-primary:hover{color:#fff;transform:translateY(-2px);box-shadow:0 6px 20px #667eea66}.related-lessons{background:#fff;border-radius:16px;padding:2rem;box-shadow:0 10px 40px #0000001a;margin-top:2rem}.attachment-download{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;padding:3rem;border-radius:12px;text-align:center}.attachment-icon{font-size:4rem;margin-bottom:1rem;opacity:.9}.download-btn{background:#fff;color:#667eea;padding:1rem 2.5rem;border-radius:8px;font-weight:700;font-size:1.125rem;border:none;transition:all .3s;box-shadow:0 4px 12px #ffffff4d;text-decoration:none;display:inline-block}.download-btn:hover{transform:translateY(-2px);box-shadow:0 6px 20px #ffffff80;color:#667eea}.sticky-top{position:sticky;top:120px;z-index:100}@media (max-width: 991px){.lesson-sidebar{margin-bottom:2rem}.lesson-title{font-size:1.5rem}.lesson-navigation{grid-template-columns:1fr}.sticky-top{position:relative;top:0}}