class7_media.css

.mobile{
    display: block;
    background-color: yellow;
    font-size: 20px;
}
.tablet{
    display: none;
}
.laptop{
    display: none;
}

@media (min-width: 768px) {
    .mobile{
        display: none;
    }
    .tablet{
        display: block;
        background-color: chartreuse;
        font-size: 30px;
    }
    
}

@media (min-width: 1024px) {
    .mobile{
        display: none;
    }
    .tablet{
        display: none;
    }
    .laptop{
        display: block;
        background-color: blue;
        font-size: 60px;
    }
    
}