和上一个笔记的Html代码相同
1 table-cell+vertical-align
.parent{
display: table-cell;
vertical-align:middle;
}
2 table-cell+vertical-align
.parent{
position: relative;
}
.child{
position: absolute;
top:50%;
transform: translateY(-50%);
}
3 flex+align-items
.parent{
display: flex;
align-items: center;
}
