body {margin: 0px;}
a {text-decoration: none; color: red;}

#container {
    height: 100vh; display: flex; flex-flow: column nowrap; gap: 3px; background-color: black;
}
#title {
     flex: 0 0 auto; font-size: 67px; text-align: center; background-color: forestgreen;
}
#menu {
    flex: 0 0 30px; background-color: khaki; display: flex; flex-flow: row nowrap;
    justify-content: space-evenly; align-items: center;
}
#container2 {
    flex: 1 1 auto; display: flex; flex-flow: row nowrap; gap: 3px;
}
#main {
    flex: 1 1 auto; background-color: chartreuse;
}
#sidebar {
    flex: 0 0 200px; background-color: chocolate;
}