Try a system like this instead:
.container {
width: 80%;
height: 200px;
background: aqua;
margin: auto;
padding: 10px;
}
.one {
width: 15%;
height: 200px;
background: red;
float: left;
}
.two {
margin-left: 15%;
height: 200px;
background: black;
}
<section class="container">
<div class="one"></div>
<div class="two"></div>
</section>
You only need to float one div if you use margin-left on the other equal to the first div’s width. This will work no matter what the zoom and will not have sub-pixel problems.