can,can’tでいったらcanです。
HTML
1<div id=b1><div id=box1 class=boxa>box1</div><div id=box2 class=boxa>box2</div><div id=box3 class=boxa>box3</div></div>
2<div id=b2><div id=box4 class=boxb></div><div id=box5 class=boxb></div><div id=box6 class=boxb></div><div id=box7 class=boxb></div></div>
3<div id=b3><div id=box8 class=boxc>box4</div><div id=box9 class=boxc>box5</div><div id=box10 class=boxc>box6</div><div id=box11 class=boxc>box7</div></div>
CSS
1* {
2 margin: 0;
3 padding: 0
4}
5#b1 {
6 position: absolute;
7 display: inline-block;
8 margin-left: 12.5vw;
9 z-index: 100
10}
11#b2 {
12 position: absolute;
13 top: 0;
14 z-index: 0;
15}
16#b3 {
17 position: absolute;
18 top: 20vh;
19 z-index: 0;
20}
21.boxa, .boxb, .boxc {
22 text-align: center;
23 display: inline-block;
24 height: 20vh;
25 line-height: 20vh;
26 width: 25vw
27}
28
29
30#box1 {
31 background: yellow
32}
33#box2 {
34 background: blue
35}
36#box3 {
37 background: green
38}
39#box4, #box8 {
40 background: skyblue
41}
42#box5, #box9 {
43 background: darkblue
44}
45#box6, #box10 {
46 background: pink
47}
48#box7, #box11 {
49 background: brown
50}
サンプル
line-heightで閃いた。
HTML
1<div id=b1><div id=box1 class=boxa>box1</div><div id=box2 class=boxa>box2</div><div id=box3 class=boxa>box3</div></div>
2<div id=b2><div id=box4 class=boxb><br>box4</div><div id=box5 class=boxb><br>box5</div><div id=box6 class=boxb><br>box6</div><div id=box7 class=boxb><br>box7</div></div>
CSS
1* {
2 margin: 0;
3 padding: 0
4}
5#b1 {
6 position: absolute;
7 display: inline-block;
8 margin-left: 12.5vw;
9 z-index: 100
10}
11#b2 {
12 position: absolute;
13 top: 0;
14 z-index: 0
15}
16.boxa, .boxb {
17 text-align: center;
18 display: inline-block;
19 height: 20vh;
20 line-height: 20vh;
21 width: 25vw
22}
23.boxb {
24 height: 40vh
25}
26
27#box1 {
28 background: yellow
29}
30#box2 {
31 background: blue
32}
33#box3 {
34 background: green
35}
36#box4 {
37 background: skyblue
38}
39#box5 {
40 background: darkblue
41}
42#box6 {
43 background: pink
44}
45#box7 {
46 background: brown
47}
サンプル
まぁもっといい書き方は他にあると思いますはひらめきでふた通りの答えを出してみました。
一番上にしない場合は
HTML
1<div id=b1><div id=box1 class=boxa>box1</div><div id=box2 class=boxa>box2</div><div id=box3 class=boxa>box3</div></div>
2<div id=b2><div id=box4 class=boxb><br>box4</div><div id=box5 class=boxb><br>box5</div><div id=box6 class=boxb><br>box6</div><div id=box7 class=boxb><br>box7</div></div>
CSS
1* {
2 margin: 0;
3 padding: 0
4}
5#b1 {
6 position: relative;
7 top: 0;
8 display: inline-block;
9 margin-left: 12.5vw;
10 z-index: 100
11}
12#b2 {
13 position: relative;
14 top: -20vh;
15 z-index: 0;
16}
17#b3 {
18 position: absolute;
19 top: 20vh;
20 z-index: 0;
21}
22.boxa, .boxb {
23 text-align: center;
24 display: inline-block;
25 height: 20vh;
26 line-height: 20vh;
27 width: 25vw
28}
29.boxb {
30 height: 40vh
31}
32
33#box1 {
34 background: yellow
35}
36#box2 {
37 background: blue
38}
39#box3 {
40 background: green
41}
42#box4 {
43 background: skyblue
44}
45#box5 {
46 background: darkblue
47}
48#box6 {
49 background: pink
50}
51#box7 {
52 background: brown
53}
最後のはサンプルないですが許してください。