I am 200px wide
I am 40% wide
I am 200px wide
I am 40% wide
.wrapper { width: 400px; border: 5px solid rebeccapurple; } .px { width: 200px; } .percent { width: 40%; }
<div class="box px">I am 200px wide</div> <div class="box percent">I am 40% wide</div> <div class="wrapper"> <div class="box px">I am 200px wide</div> <div class="box percent">I am 40% wide</div> </div>