<div class="row">
<div class="col1"></div>
<div class="col2"></div>
</div>
.row {
background-color: #eee;
width:200px;
display: flex;
flex-wrap: wrap;
}
.col1 {
background-color: #333;
height: 50px;
width:100.01px;
}
.col2 {
background-color: red;
height: 50px;
width:100px;
}