:root{--primary-color:#4a90e2;--primary-light:rgba(74,144,226,0.1);--text-primary:#333;--text-secondary:#666;--card-bg:#ffffff;--card-border:#eaeaea;--card-shadow:0 5px 15px rgba(0,0,0,0.05);--progress-bg:#e9ecef}.dark-mode{--text-primary:#fff;--text-secondary:#aaa;--card-bg:#2d2d2d;--card-border:#3d3d3d;--progress-bg:#444}.lessons-container{padding:40px 0}.breadcrumb{background-color:transparent;padding-left:0}.breadcrumb-item a{color:var(--primary-color);text-decoration:none}.breadcrumb-item.active{color:var(--text-secondary)}.subject-header{margin-bottom:40px}.subject-title{font-size:2.2rem;font-weight:700;margin-bottom:20px;color:var(--text-primary)}.subject-description{font-size:1.1rem;color:var(--text-secondary);margin-bottom:20px;line-height:1.6}.tutorial-meta{display:flex;flex-wrap:wrap;gap:30px;margin-bottom:30px}.meta-item{display:flex;align-items:center;gap:10px}.meta-icon{width:40px;height:40px;border-radius:50%;background-color:var(--primary-light);display:flex;align-items:center;justify-content:center;color:var(--primary-color)}.meta-content{display:flex;flex-direction:column}.meta-label{font-size:0.9rem;color:var(--text-secondary)}.meta-value{font-weight:600;color:var(--text-primary)}.progress-container{background-color:var(--card-bg);border-radius:10px;padding:20px;margin-bottom:30px;box-shadow:var(--card-shadow);border:1px solid var(--card-border)}.progress-title{font-size:1.1rem;font-weight:600;margin-bottom:15px;color:var(--text-primary)}.progress-bar-container{height:10px;background-color:var(--progress-bg);border-radius:5px;overflow:hidden;margin-bottom:10px}.progress-bar{height:100%;background-color:var(--primary-color);border-radius:5px}.progress-text{display:flex;justify-content:space-between;color:var(--text-secondary);font-size:0.9rem}.lessons-list{display:flex;flex-direction:column;gap:20px}.lesson-card{background-color:var(--card-bg);border-radius:10px;padding:20px;box-shadow:var(--card-shadow);border:1px solid var(--card-border);transition:transform 0.3s ease,box-shadow 0.3s ease;display:flex;align-items:center;gap:20px}.lesson-card:hover{transform:translateY(-5px);box-shadow:0 10px 25px rgba(0,0,0,0.1);border-color:var(--primary-color)}.lesson-number{width:50px;height:50px;min-width:50px;background-color:var(--primary-light);color:var(--primary-color);border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:1.2rem}.lesson-content{flex-grow:1}.lesson-title{font-size:1.3rem;font-weight:600;margin-bottom:5px;color:var(--text-primary)}.lesson-title a{color:inherit;text-decoration:none;transition:color 0.2s}.lesson-title a:hover{color:var(--primary-color)}.lesson-meta{color:var(--text-secondary);font-size:0.9rem;display:flex;gap:15px}.lesson-meta-item{display:flex;align-items:center;gap:5px}.lesson-action{color:var(--primary-color)}.sidebar-card{background-color:var(--card-bg);border-radius:10px;padding:20px;margin-bottom:20px;box-shadow:var(--card-shadow);border:1px solid var(--card-border)}.sidebar-title{font-size:1.2rem;font-weight:600;margin-bottom:15px;color:var(--text-primary)}.related-list{display:flex;flex-direction:column;gap:15px}.related-item{display:flex;gap:10px;align-items:center}.related-icon{width:40px;height:40px;min-width:40px;background-color:var(--primary-light);color:var(--primary-color);border-radius:8px;display:flex;align-items:center;justify-content:center}.related-title{font-weight:500;color:var(--text-primary)}.related-title a{color:inherit;text-decoration:none;transition:color 0.2s}.related-title a:hover{color:var(--primary-color)}.cta-card{background-color:var(--primary-color);color:white;border-radius:10px;padding:25px;text-align:center}.cta-title{font-size:1.3rem;font-weight:600;margin-bottom:15px}.cta-text{margin-bottom:20px;opacity:0.9}.cta-button{display:inline-block;background-color:white;color:var(--primary-color);padding:10px 20px;border-radius:6px;font-weight:600;text-decoration:none;transition:all 0.2s}.cta-button:hover{background-color:rgba(255,255,255,0.9);color:var(--primary-color);text-decoration:none}@media (max-width:767px){.sidebar{margin-top:40px}}