* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

header {
    background: #2e58af;
    color: white;
    text-align: center;
    padding: 15px;
}

.container {
    display: flex;
    flex: 1;
}

aside {
    width: 20%;
    padding: 20px;
}

main {
    flex: 1;
    padding: 20px;
}