body {
    margin: 0 auto;
    max-width:800px;
    width:90%
}

@media (min-width: 640px) {
 html{
    background-color: #eaf6ff ;
}
}

h1{
    font-size: 1.5rem;
}

@media (min-width: 500px) {
    h1{font-size:2em;}
}

@media (min-width:640px){
    h1{font-size: 2.5rem}
    #stretchable-grid-items li{width:25%;}
}

#fixed-size-grid-items li{
    display: grid;
    flex-wrap: wrap;
    font-size: 0.8rem;
    margin:10px;
}

#fixed-size-grid-items aside {
    width:170px
}

#fixed-size-grid-items ul{
    padding-left: 0;
    flex-wrap:wrap;
    display:flex;
}

#stretchable-grid-items li{
    display:grid;
    flex-wrap:wrap;
    font-size: 0.8rem;
    width: 100%
}

#stretchable-grid-items aside{
    margin:10px;
}
#stretchable-grid-items ul{
    padding-left:0;
    flex-wrap:wrap;
    display:flex;
    margin-left: -10px;
    margin-right:-10px;
    margin-top: 1rem;
    margin-bottom: 1rem;
}

@media (min-width:480px){
    #stretchable-grid-items li{width:50%};
}

@media (min-width:640px){
    #stretchable-grid-items li{width:25%;}
}