@media screen and (min-width:1200px){

    body{
        background-color: aquamarine;
    }
    
    #holderA1{
        grid-template-columns: repeat(3,1fr);
        max-width: 1200px;
    }

    .pbox{
        min-width: 300px;
        min-height: 295px;
        margin-bottom: 40px;
        
    }
}