<div class="block-gallery">
<div class="box a">A</div>
<div class="box b">B</div>
<div class="box c">C</div>
<div class="box d">D</div>
</div>.block-gallery {
display: grid;
grid-gap: 10px;
grid-template-columns: 100px 100px 100px;
background-color: #fff;
color: #444;
}
.box {
background-color: #444;
color: #fff;
border-radius: 5px;
padding: 20px;
font-size: 150%;
}
.a {
grid-column: 1 / 3;
grid-row: 1;
}
.b {
grid-column: 3 ;
grid-row: 1 / 3;
}
.c {
grid-column: 1 ;
grid-row: 2 ;
}
.d {
grid-column: 2;
grid-row: 2;
}