:root{--primary-color: #4A90E2;--secondary-color: #7B68EE;--success-color: #2ECC71;--warning-color: #F39C12;--danger-color: #E74C3C;--bg-color: #F8F9FA;--card-bg: #FFFFFF;--text-primary: #2C3E50;--text-secondary: #7F8C8D;--border-color: #E1E8ED;--sidebar-bg: #2C3E50;--sidebar-hover: #34495E;--shadow-sm: 0 2px 4px rgba(0,0,0,.08);--shadow-md: 0 4px 8px rgba(0,0,0,.12);--shadow-lg: 0 8px 16px rgba(0,0,0,.15);--border-radius: 8px;--border-radius-sm: 6px;--border-radius-lg: 12px;--transition: all .3s ease}*{margin:0;padding:0;box-sizing:border-box}body{font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;background:var(--bg-color);color:var(--text-primary);line-height:1.6;overflow-x:hidden}.sidebar{position:fixed;left:0;top:0;width:260px;height:100vh;background:var(--sidebar-bg);color:#fff;padding:20px 0;z-index:1000;transition:var(--transition);overflow-y:auto}.sidebar-header{display:flex;align-items:center;justify-content:space-between;padding:0 20px 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12px;border-radius:var(--border-radius);transition:var(--transition)}.user-profile:hover{background:var(--bg-color)}.user-profile img{width:40px;height:40px;border-radius:50%;object-fit:cover}.user-profile span{font-weight:500}.content-section{display:none;padding:32px;animation:fadeIn .3s ease}.content-section.active{display:block}@keyframes fadeIn{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.breadcrumb{display:flex;align-items:center;gap:8px;color:var(--text-secondary);font-size:14px;margin-bottom:24px}.breadcrumb i{color:var(--primary-color)}h1{font-size:32px;font-weight:700;margin-bottom:24px;color:var(--text-primary)}h2{font-size:24px;font-weight:600;margin-bottom:20px;color:var(--text-primary)}h3{font-size:18px;font-weight:600;color:var(--text-primary)}.welcome-banner{background:linear-gradient(135deg,var(--primary-color),var(--secondary-color));border-radius:var(--border-radius-lg);padding:40px;color:#fff;display:flex;align-items:center;justify-content:space-between;margin-bottom:32px;box-shadow:var(--shadow-md)}.welcome-content h1{color:#fff;margin-bottom:12px}.welcome-content p{font-size:16px;margin-bottom:24px;opacity:.95}.overall-progress{display:flex;gap:32px}.progress-stat{display:flex;flex-direction:column}.stat-value{font-size:32px;font-weight:700}.stat-label{font-size:14px;opacity:.9}.welcome-image{width:300px;height:200px;border-radius:var(--border-radius);overflow:hidden}.welcome-image img{width:100%;height:100%;object-fit:cover}.dashboard-section{margin-bottom:40px}.dashboard-row{display:grid;grid-template-columns:1fr 1fr;gap:24px;margin-bottom:40px}.dashboard-section.half{margin-bottom:0}.schedule-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}.schedule-card{background:#fff;border-radius:var(--border-radius);padding:24px;border:1px solid var(--border-color);transition:var(--transition)}.schedule-card:hover{box-shadow:var(--shadow-md);transform:translateY(-4px)}.schedule-card.live{border:2px solid var(--success-color);background:linear-gradient(to bottom,#fff,#f0fdf4)}.schedule-time{display:flex;align-items:center;gap:8px;font-size:14px;color:var(--text-secondary);margin-bottom:12px;flex-wrap:wrap}.live-badge{background:var(--success-color);color:#fff;padding:4px 12px;border-radius:12px;font-size:12px;font-weight:600;margin-left:auto}.countdown{background:var(--warning-color);color:#fff;padding:4px 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var(--border-color);border-radius:var(--border-radius);outline:none;font-size:14px}.message-input input:focus{border-color:var(--primary-color)}.forums-list{display:flex;flex-direction:column;gap:20px}.forum-card{background:#fff;border-radius:var(--border-radius);padding:24px;border:1px solid var(--border-color);display:flex;align-items:center;gap:20px;transition:var(--transition)}.forum-card:hover{box-shadow:var(--shadow-md);transform:translateY(-2px)}.forum-icon{width:64px;height:64px;border-radius:var(--border-radius);display:flex;align-items:center;justify-content:center;font-size:32px;background:var(--bg-color);color:var(--primary-color)}.forum-info{flex:1}.forum-info h3{margin-bottom:8px}.forum-info p{color:var(--text-secondary);font-size:14px;margin-bottom:12px}.forum-stats{display:flex;gap:20px;font-size:13px;color:var(--text-secondary)}.forum-stats 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input:checked+.toggle-slider:before{transform:translate(24px)}.certificates-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:20px}.certificate-card{background:var(--bg-color);border-radius:var(--border-radius);padding:24px;text-align:center}.certificate-card i{font-size:48px;color:var(--warning-color);margin-bottom:12px}.certificate-card h4{margin-bottom:8px}.certificate-card p{font-size:13px;color:var(--text-secondary);margin-bottom:16px}.btn{padding:12px 24px;border:none;border-radius:var(--border-radius-sm);font-size:14px;font-weight:600;cursor:pointer;transition:var(--transition);display:inline-flex;align-items:center;justify-content:center;gap:8px;text-decoration:none}.btn-primary{background:var(--primary-color);color:#fff}.btn-primary:hover{background:#3a7bc8}.btn-secondary{background:#fff;color:var(--primary-color);border:1px solid var(--primary-color)}.btn-secondary:hover{background:var(--primary-color);color:#fff}.btn-success{background:var(--success-color);color:#fff}.btn-success:hover{background:#27ae60}.btn-danger{background:var(--danger-color);color:#fff}.btn-danger:hover{background:#c0392b}.btn-sm{padding:8px 16px;font-size:13px}.btn-block{width:100%}.modal{display:none;position:fixed;top:0;left:0;width:100%;height:100%;background:#00000080;z-index:2000;align-items:center;justify-content:center}.modal.active{display:flex}.modal-content{background:#fff;border-radius:var(--border-radius-lg);max-width:600px;width:90%;max-height:90vh;overflow-y:auto;animation:modalSlideIn .3s ease}.modal-content.notification-panel{max-width:400px}@keyframes modalSlideIn{0%{opacity:0;transform:translateY(-50px)}to{opacity:1;transform:translateY(0)}}.modal-header{padding:24px;border-bottom:1px solid var(--border-color);display:flex;align-items:center;justify-content:space-between}.modal-header h2{margin:0}.modal-close{background:none;border:none;font-size:24px;color:var(--text-secondary);cursor:pointer;transition:var(--transition)}.modal-close:hover{color:var(--text-primary)}.modal-body{padding:24px}.modal-body h3{margin-bottom:8px}.modal-body>p{color:var(--text-secondary);font-size:14px;margin-bottom:24px}.upload-area{border:2px dashed var(--border-color);border-radius:var(--border-radius);padding:48px 24px;text-align:center;margin-bottom:24px;transition:var(--transition)}.upload-area:hover{border-color:var(--primary-color);background:var(--bg-color)}.upload-area i{font-size:48px;color:var(--primary-color);margin-bottom:16px}.upload-area p{color:var(--text-secondary);margin-bottom:16px}.modal-footer{padding:24px;border-top:1px solid var(--border-color);display:flex;justify-content:flex-end;gap:12px}.notification-item{display:flex;gap:16px;padding:16px;border-bottom:1px solid var(--border-color);transition:var(--transition)}.notification-item:hover{background:var(--bg-color)}.notification-item.unread{background:#e6f2ff}.notification-item i{width:40px;height:40px;border-radius:50%;display:flex;align-items:center;justify-content:center;background:var(--bg-color);color:var(--primary-color);font-size:18px;flex-shrink:0}.notification-content{flex:1}.notification-content h4{margin-bottom:4px}.notification-content p{font-size:13px;color:var(--text-secondary);margin-bottom:4px}.notification-time{font-size:12px;color:var(--text-secondary)}::-webkit-scrollbar{width:8px;height:8px}::-webkit-scrollbar-track{background:var(--bg-color)}::-webkit-scrollbar-thumb{background:var(--border-color);border-radius:4px}::-webkit-scrollbar-thumb:hover{background:var(--text-secondary)}@media (max-width: 1200px){.schedule-grid{grid-template-columns:repeat(2,1fr)}.profile-layout{grid-template-columns:1fr}}@media (max-width: 968px){.sidebar{transform:translate(-100%)}.sidebar.active{transform:translate(0)}.sidebar-toggle{display:block}.mobile-menu-toggle{display:flex;align-items:center;justify-content:center}.main-content{margin-left:0}.welcome-banner{flex-direction:column;text-align:center}.welcome-image{width:100%;max-width:400px}.overall-progress{justify-content:center}.schedule-grid,.dashboard-row{grid-template-columns:1fr}.communication-layout{grid-template-columns:1fr;height:auto}.contacts-sidebar{display:none}.form-row{grid-template-columns:1fr}}@media (max-width: 640px){.top-header{flex-direction:column;gap:16px}.search-bar{max-width:100%}.content-section{padding:20px}.welcome-banner{padding:24px}.overall-progress{flex-direction:column;gap:16px}.course-progress-grid,.courses-grid,.live-classes-grid,.recordings-grid,.quiz-grid,.resources-grid,.study-groups-grid{grid-template-columns:1fr}.assignment-main{flex-direction:column}.assignment-main img{width:100%;height:200px}.assignment-actions,.filters-bar{flex-direction:column}.filter-group,.filter-select{width:100%}}