HTML
<div class="layout">
<div class="cell-1">
<img src="characters/a.png">
</div>
<div class="cell-3">
<img src="characters/b.png">
</div>
<div class="cell-2">
<img src="characters/b.png">
</div>
<div class="cell-2">
<img src="characters/b.png">
</div>
</div>
CSS
.layout {
display: flex;
flex-wrap: wrap;
}
.layout {
display: flex;
flex-wrap: wrap;
}
.layout .cell-1 {
width: 25%;
}
.layout .cell-2 {
width: 50%;
}
.layout .cell-3 {
width: 75%;
}
.layout img {
width: 100%;
}
@media (max-width: 800px) {
.layout {
flex-direction: column;
}
.layout .cell-1, .layout .cell-2 {
width: 100%
}
}