.sidebar{width:250px;height:100vh;background:var(--surface-color);border-right:var(--glass-border);display:flex;flex-direction:column;position:fixed;left:0;top:0;z-index:100;box-shadow:5px 0 15px #00000080}.sidebar-header{padding:20px;text-align:center;border-bottom:var(--glass-border)}.logo{font-size:1.5rem;font-weight:700;color:var(--text-color);letter-spacing:1px}.logo-link{text-decoration:none;cursor:pointer}.logo-link:hover .logo{opacity:.8}.neon-text{color:var(--primary-color);text-shadow:0 0 5px var(--primary-color)}.sidebar-nav{flex:1;padding:20px 0;overflow-y:auto}.sidebar-nav ul{list-style:none;padding:0;margin:0}.sidebar-nav li{margin-bottom:5px}.sidebar-nav a{display:block;padding:12px 20px;color:var(--text-muted);text-decoration:none;transition:all .3s ease;border-left:3px solid transparent}.sidebar-nav a:hover,.sidebar-nav a.active{background:#00f0ff0d;color:var(--primary-color);border-left-color:var(--primary-color);text-shadow:0 0 8px rgba(0,240,255,.4)}.sidebar-footer{padding:16px;border-top:var(--glass-border);background:linear-gradient(135deg,#00f0ff0d,#8a2be20d);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.user-profile{display:flex;align-items:center;gap:12px;padding:12px;background:#ffffff08;border-radius:12px;margin-bottom:12px;border:1px solid rgba(255,255,255,.05);transition:all .3s ease}.user-profile:hover{background:#ffffff0d;border-color:#00f0ff33;box-shadow:0 4px 12px #00f0ff1a}.user-avatar{width:42px;height:42px;border-radius:50%;background:linear-gradient(135deg,var(--primary-color),var(--secondary-color));display:flex;align-items:center;justify-content:center;font-weight:700;font-size:1.2rem;color:#fff;flex-shrink:0;box-shadow:0 0 15px #00f0ff4d}.user-details{display:flex;flex-direction:column;gap:2px;flex:1;min-width:0}.username{font-weight:600;color:var(--text-color);font-size:.95rem;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.role{font-size:.75rem;color:var(--secondary-color);text-transform:capitalize;font-weight:500;letter-spacing:.5px}.btn-logout{width:100%;padding:10px 16px;background:#ff3b301a;border:1px solid rgba(255,59,48,.3);color:#ff3b30;cursor:pointer;transition:all .3s ease;border-radius:8px;font-weight:500;font-size:.9rem;display:flex;align-items:center;justify-content:center;gap:8px}.btn-logout:hover{background:#ff3b3033;border-color:#ff3b30;box-shadow:0 0 15px #ff3b304d;transform:translateY(-1px)}.btn-logout:active{transform:translateY(0)}.navbar{display:flex;justify-content:space-between;align-items:center;padding:1rem 2rem;background-color:var(--bg-secondary);border-bottom:1px solid var(--border-color)}.navbar-brand a{font-size:1.5rem;font-weight:700;color:var(--text-primary)}.navbar-links{display:flex;gap:1.5rem;align-items:center}.navbar-links a{color:var(--text-secondary);transition:color .2s}.navbar-links a:hover{color:var(--accent-primary)}.btn-logout{background:none;border:1px solid var(--error);color:var(--error);padding:.5rem 1rem;border-radius:.375rem;cursor:pointer;transition:all .2s}.btn-logout:hover{background-color:var(--error);color:#fff}.app-layout{min-height:100vh;display:flex;flex-direction:column}.main-content{flex:1;display:flex;flex-direction:column;transition:margin-left .3s ease}.main-content.with-sidebar{margin-left:250px;padding:20px}@media(max-width:768px){.sidebar{transform:translate(-100%);transition:transform .3s ease}.sidebar.open{transform:translate(0)}.main-content.with-sidebar{margin-left:0}}.home-container{min-height:100vh;display:flex;flex-direction:column;justify-content:center;align-items:center;padding:40px;background:radial-gradient(circle at 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#00000080;text-align:center}.auth-title{color:var(--primary-color);font-size:2rem;margin-bottom:10px;text-transform:uppercase;letter-spacing:2px}.auth-subtitle{color:var(--text-muted);margin-bottom:30px}.auth-error{background:#ff00551a;border:1px solid var(--error-color);color:var(--error-color);padding:10px;border-radius:5px;margin-bottom:20px}.form-group{margin-bottom:20px;text-align:left}.form-group label{display:block;color:var(--text-color);margin-bottom:8px;font-size:.9rem}.form-group input,.form-group select{width:100%;padding:12px;background:#0000004d;border:1px solid var(--border-color);border-radius:8px;color:#fff;font-size:1rem;transition:all .3s ease}.form-group input:focus,.form-group select:focus{outline:none;border-color:var(--primary-color);box-shadow:0 0 10px #00f0ff33}.form-group select 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h1{font-size:2.5rem;color:var(--primary-color);text-transform:uppercase;letter-spacing:2px}.challenges-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:20px}.challenge-card{background:var(--surface-color);border:var(--glass-border);border-radius:12px;padding:20px;transition:all .3s ease;position:relative;overflow:hidden}.challenge-card:before{content:"";position:absolute;top:0;left:0;width:100%;height:4px;background:linear-gradient(90deg,var(--primary-color),var(--secondary-color));opacity:0;transition:opacity .3s ease}.challenge-card:hover{transform:translateY(-5px);box-shadow:0 5px 15px #0000004d}.challenge-card:hover:before{opacity:1}.challenge-header{display:flex;justify-content:space-between;align-items:flex-start;margin-bottom:15px}.challenge-title{font-size:1.2rem;font-weight:700;color:var(--text-color);margin:0}.difficulty-badge{padding:4px 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20px}.rank-user{font-size:1.2rem;font-weight:700;color:var(--text-color);margin-bottom:5px}.rank-stats{font-size:.9rem;color:var(--text-muted)}.rank-score{font-size:1.5rem;font-weight:700;color:var(--primary-color)}.pts{font-size:.8rem;color:var(--text-muted);margin-left:5px}.courses-page{padding:2rem;max-width:1200px;margin:0 auto}.page-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:2rem}.page-header h1{margin:0;font-size:2rem;background:linear-gradient(135deg,#00f0ff,#7000ff);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent}.btn-primary{padding:.75rem 1.5rem;background:linear-gradient(135deg,#00f0ff,#7000ff);color:#fff;border:none;border-radius:8px;font-weight:600;cursor:pointer;transition:all .3s ease}.btn-primary:hover{transform:translateY(-2px);box-shadow:0 10px 30px #00f0ff4d}.btn-primary:disabled{opacity:.5;cursor:not-allowed}.btn-secondary{padding:.75rem 1.5rem;background:#ffffff1a;color:#fff;border:1px 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p{color:var(--text-muted);font-size:.9rem}.submissions-list{background:var(--surface-color);border:var(--glass-border);border-radius:12px;padding:20px}.submission-item{display:grid;grid-template-columns:120px 1fr 100px 120px;gap:15px;padding:15px;border-bottom:1px solid rgba(255,255,255,.05);align-items:center}.submission-item:last-child{border-bottom:none}.submission-challenge{color:var(--text-color);font-weight:500}.submission-lang{color:var(--text-muted);text-transform:capitalize}.submission-date{color:var(--text-muted);font-size:.9rem}.empty-state{background:var(--surface-color);border:var(--glass-border);border-radius:12px;padding:60px 40px;text-align:center}.empty-state h3{color:var(--text-color);font-size:1.8rem;margin-bottom:15px}.empty-state p{color:var(--text-muted);margin-bottom:25px;font-size:1.1rem}.btn-primary{display:inline-block;padding:12px 30px;background:var(--primary-color);color:#000;text-decoration:none;border-radius:8px;font-weight:700;transition:all .3s 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