*{
    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;
}

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

@media screen and (min-width: 1050px){
    main{
        display: flex;
        flex-wrap: wrap;
    }
    .red, .blue{
        width: 25%;
    }
    .green, .pink{
        width: 25%;
    }
}

@media screen and (orientation:landscape){
    header{
        background-color: rgb(255, 0, 170);
        color: green;
    }
}