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


.box {
    margin: auto;
    border: 1px solid black;
    height: 300px;
    background-color: rgb(255, 255, 255);
    float: left;
    
}

.one {
    width: 50%;
}

.two {
    width: 33.33%;
}

.three {
    width: 100%;
}


@media only screen and (max-width: 1100px) {
    .two{
        width: 100%;
    }
}