*{
    box-sizing: border-box;
}
 
body{
    margin: 0;
 
}
 
.container{
    max-width: 960px;
    margin: 0 auto;
    outline: 3px solid black;
 
}
 
.red{
    display: flex;
 
}
 
.flex-item{
    flex-basis: 50px;
    height: 200px;
}
 
.rozi{
    background-color: pink;
    flex-grow: 3;
}
 
.zuti{
    background-color: yellow;
    flex-grow: 2;
}
 
.ljubicasta{
    background-color: purple;
    flex-grow: 1;
}