:root{--primary:#0071e3;--primary-hover:#0077ed;--success:#34c759;--warning:#ff9500;--error:#ff3b30;--text:#1d1d1f;--text-secondary:#86868b;--background:#fff;--background-secondary:#f5f5f7;--border:#d2d2d7;--card-shadow:0 4px 24px rgba(0,0,0,.08);--radius:12px;--radius-sm:8px}*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen,Ubuntu,sans-serif;background:var(--background-secondary);color:var(--text);line-height:1.5;-webkit-font-smoothing:antialiased}.auth-page{min-height:100vh;display:flex;align-items:center;justify-content:center;padding:20px}.auth-container{width:100%;max-width:420px}.auth-card{background:var(--background);border-radius:var(--radius);padding:40px;box-shadow:var(--card-shadow)}.auth-logo{text-align:center;margin-bottom:32px}.auth-logo h1{font-size:24px;font-weight:600;color:var(--text)}.auth-logo p{color:var(--text-secondary);margin-top:4px}.auth-form{display:flex;flex-direction:column;gap:20px}.auth-footer{text-align:center;margin-top:24px;color:var(--text-secondary)}.auth-footer a{color:var(--primary);text-decoration:none}.form-group{display:flex;flex-direction:column;gap:6px}.form-group label{font-size:14px;font-weight:500;color:var(--text)}.form-group input,.form-group select,.form-group textarea{padding:12px 16px;border:1px solid var(--border);border-radius:var(--radius-sm);font-size:16px;transition:border-color .2s , box-shadow .2s}.form-group input:focus,.form-group select:focus,.form-group textarea:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(0,113,227,.1)}.form-group small{font-size:12px;color:var(--text-secondary)}.form-row{display:grid;grid-template-columns:1fr 1fr;gap:16px}.btn{padding:12px 24px;border:none;border-radius:var(--radius-sm);font-size:16px;font-weight:500;cursor:pointer;transition:all .2s;text-decoration:none;display:inline-flex;align-items:center;justify-content:center;gap:8px}.btn-primary{background:var(--primary);color:#fff}.btn-primary:hover{background:var(--primary-hover)}.btn-secondary{background:var(--background-secondary);color:var(--text)}.btn-secondary:hover{background:var(--border)}.btn-success{background:var(--success);color:#fff}.btn-danger{background:var(--error);color:#fff}.btn-full{width:100%}.btn-sm{padding:8px 16px;font-size:14px}.alert{padding:14px 18px;border-radius:var(--radius-sm);margin-bottom:20px;font-size:14px}.alert-error{background:#fff2f2;color:var(--error);border:1px solid #ffcdd2}.alert-success{background:#f0fff4;color:#276749;border:1px solid #c6f6d5}.alert-warning{background:#fffbeb;color:#92400e;border:1px solid #fde68a}.app-layout{display:flex;min-height:100vh}.sidebar{width:260px;background:var(--background);border-right:1px solid var(--border);padding:24px 0;position:fixed;height:100vh;overflow-y:auto}.sidebar-logo{padding:0 24px 24px;border-bottom:1px solid var(--border);margin-bottom:24px}.sidebar-logo h1{font-size:18px;font-weight:600}.sidebar-logo span{font-size:12px;color:var(--text-secondary)}.sidebar-nav{list-style:none}.sidebar-nav a{display:flex;align-items:center;gap:12px;padding:12px 24px;color:var(--text);text-decoration:none;transition:background .2s}.sidebar-nav a:hover,.sidebar-nav a.active{background:var(--background-secondary)}.sidebar-nav a.active{color:var(--primary);font-weight:500}.main-content{flex:1;margin-left:260px;padding:32px}.page-header{margin-bottom:32px}.page-header h1{font-size:28px;font-weight:600}.page-header p{color:var(--text-secondary);margin-top:4px}.card{background:var(--background);border-radius:var(--radius);box-shadow:var(--card-shadow);padding:24px;margin-bottom:24px}.card-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px}.card-header h2{font-size:18px;font-weight:600}.course-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:24px}.course-card{background:var(--background);border-radius:var(--radius);box-shadow:var(--card-shadow);overflow:hidden;transition:transform .2s , box-shadow .2s}.course-card:hover{transform:translateY(-4px);box-shadow:0 8px 32px rgba(0,0,0,.12)}.course-card-header{background:linear-gradient(135deg,var(--primary),#00c7be);padding:32px 24px;color:#fff}.course-card-header h3{font-size:20px;font-weight:600;margin-bottom:4px}.course-card-header p{opacity:.9;font-size:14px}.course-card-body{padding:24px}.course-progress{margin-bottom:16px}.progress-bar{height:8px;background:var(--background-secondary);border-radius:4px;overflow:hidden;margin-top:8px}.progress-bar-fill{height:100%;background:var(--success);border-radius:4px;transition:width .3s}.course-meta{display:flex;gap:16px;color:var(--text-secondary);font-size:14px}.table-container{overflow-x:auto}table{width:100%;border-collapse:collapse}th,td{padding:14px 16px;text-align:left;border-bottom:1px solid var(--border)}th{font-weight:600;color:var(--text-secondary);font-size:12px;text-transform:uppercase;letter-spacing:.5px}tr:hover{background:var(--background-secondary)}.badge{display:inline-block;padding:4px 10px;border-radius:20px;font-size:12px;font-weight:500}.badge-success{background:#dcfce7;color:#166534}.badge-warning{background:#fef3c7;color:#92400e}.badge-error{background:#fee2e2;color:#991b1b}.badge-info{background:#dbeafe;color:#1e40af}.lesson-container{max-width:800px;margin:0 auto}.lesson-content{background:var(--background);border-radius:var(--radius);padding:40px;box-shadow:var(--card-shadow)}.lesson-content h1,.lesson-content h2,.lesson-content h3{margin-top:24px;margin-bottom:16px}.lesson-content p{margin-bottom:16px}.lesson-content ul,.lesson-content ol{margin-bottom:16px;padding-left:24px}.lesson-nav{display:flex;justify-content:space-between;margin-top:32px;padding-top:24px;border-top:1px solid var(--border)}.quiz-question{background:var(--background);border-radius:var(--radius);padding:24px;margin-bottom:24px;box-shadow:var(--card-shadow)}.quiz-question h3{margin-bottom:16px}.quiz-options{display:flex;flex-direction:column;gap:12px}.quiz-option{display:flex;align-items:center;gap:12px;padding:16px;border:1px solid var(--border);border-radius:var(--radius-sm);cursor:pointer;transition:all .2s}.quiz-option:hover{border-color:var(--primary);background:rgba(0,113,227,.05)}.quiz-option.selected{border-color:var(--primary);background:rgba(0,113,227,.1)}.quiz-option input{display:none}.avatar{width:40px;height:40px;border-radius:50%;background:var(--primary);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:600;font-size:16px}.avatar-sm{width:32px;height:32px;font-size:14px}@media (max-width:768px){.sidebar{transform:translateX(-100%);z-index:1000;transition:transform .3s}.sidebar.open{transform:translateX(0)}.main-content{margin-left:0;padding:16px}.form-row{grid-template-columns:1fr}.course-grid{grid-template-columns:1fr}.auth-card{padding:24px}}