body {
    margin: 0;
}

header {
    text-align: center;
}

header img {
    width: 50px;
}

.sidebar {
    position: fixed;
    left: 0;
    top: 0;
    width: 200px;
    height: 100vh;
}

main {
    margin-left: 220px;
}

main {
    margin-left: 220px;
}