.logo {
    position: fixed;
    top: 20px;
    left: 20px;
    width: 200px;
    height: 200px;
    background: url('/logo.png') center/contain no-repeat;
    z-index: 10;
    opacity: 0.9;
    transition: opacity 0.3s;
}

.logo:hover {
    opacity: 1;
    transform: scale(1.05);}