*{
    box-sizing: border-box;
}
.container{
    margin: 0px auto;
    width: 90%;
}

header {
    background-color:yellow;
    padding-top: 2em;
    text-align: center;
    height: 200px;
}

main{
    display: flex;
    flex-wrap: wrap;
}

.red{
    width: 100%;
    height: 200px;
    background-color: red;
}

.blue{
    width: 100%;
    height: 200px;
    background-color:blue;
}

.green{
    width: 100%;
    height: 200px;
    background-color: green;
}

@media screen and (min-width: 576px) and (max-width:992px){
    main{
        display: flex;
        flex-wrap: wrap;
    }
    .red, .blue, .purple, .green, .orange, .gray, .black, .yellow, .white, .lightgreen {
        width: 50%;
    }
    .pink{
        display: none;
    }
   
}

@media screen and (min-width: 993px){
    main{
        display: flex;
        flex-wrap: wrap;
    }
    .red, .blue{
        width: 33%;
    }
    .green{
        width: 34%;
    }
}

/*@media screen and (min-width: 1050px){
    main{
        display: flex;
        flex-wrap: wrap;
    }
    .red, .blue{
        width: 33%;
    }
    .green{
        width: 34%;
    }
}*/

@media screen and (orientation:landscape){
    header{
        background-color: orange;
        color: green;
    }
    .red, .blue, .green{
        height: 100px;
        border: 5px dotted;
    }
}