body{
    max-width:800px;
    width: 90%;
    margin-left: auto;
    margin-right: auto;
}
#stretchable-grid-items li{
    width:100%;
}
@media(min-width:480px){
    #stretchable-grid-items li{
        width:50%;
    }
}
@media(min-width: 640px){
    html{
        background-color: #eaf6ff;
    }
    h1{
        font-size: 2.5rem;
    }
    #stretchable-grid-items li{
        width:25%;
    }
    
}
@media(max-width:500px){
    h1{
        font-size: 1.5rem;
    }
}

aside{
    margin: 10px;
}
#fixed-size-grid-items aside{
    font-size:0.8rem;
    width: 170px;
}
#fixed-size-grid-items li{
    font-size: 0.8rem;
}

ul{
    list-style-type: none;
    padding-left: 0;
    display:flex;
    flex-wrap:wrap;
}
#stretchable-grid-items ul{
    margin: 1rem -10px;
    padding: 0;
}