main .heart{
animation: heart 1.3s ease-in-out 2.7s infinite alternate;
}
//margin-top會發生卡頓
@keyframes heart{
from{margin-top:0px;}
to{margin-top:-6px;}
}
//用transform就流暢了
@keyframes heart{
from{transform:translate(0,0)}
to{transform:translate(0,6px)}
}