.layout{min-height:100vh;display:flex;flex-direction:column}.header{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;padding:1rem 0;box-shadow:0 2px 8px #0000001a}.header-content{max-width:1200px;margin:0 auto;padding:0 2rem;display:flex;align-items:center;justify-content:space-between;gap:2rem}.logo{margin:0;font-size:1.5rem;font-weight:700;white-space:nowrap}.nav{display:flex;gap:1rem;flex:1}.nav-link{color:#fff;text-decoration:none;padding:.5rem 1rem;border-radius:8px;transition:all .3s ease;font-weight:500}.nav-link:hover{background:#ffffff1a}.nav-link.active{background:#fff3}.user-info{display:flex;align-items:center;gap:.5rem}.username{font-weight:500;white-space:nowrap}.difficulty-badge{background:#ffffff40;padding:.5rem 1rem;border-radius:20px;font-weight:600;font-size:.9rem;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.main-content{flex:1;max-width:1200px;width:100%;margin:0 auto;padding:2rem}.footer{background:#f8f9fa;padding:1.5rem;text-align:center;border-top:1px solid #e9ecef;margin-top:auto}.footer p{margin:0;color:#6c757d}@media(max-width:768px){.header-content{flex-direction:column;align-items:stretch}.nav{flex-direction:column;gap:.5rem}.nav-link{text-align:center}.main-content{padding:1rem}}