.b1{
    background-color: rgb(19, 189, 36);
    float: left;
    }
    
    .b2{
        background-color: rgb(31, 31, 219);
        float: left;
    }
    
    div{
        width: 200px;
        height: 200px;
    }
    
    .cf{
        clear: left;
    }