repeat(4, 1fr) / repeat(3, 1fr)
1fr 2fr/ 1fr 2fr 2fr 1fr
1fr 30px / 1fr 50px 1fr 2fr
15px 1fr 25px/ 60px 1fr 90px
[top] "hd hd" 10px [middle] "nv mn" 30px [bottom]
column
row
column dense
row dense
grid表示
0
1-row2
2
3
4-column2
5
6
7
8
9