<body>
<div class="container">
<div class="box1">
</div>
<div class="box2">
</div>
</div>
</body>
body {
padding: 20px;
height: 300px;
}
.container {
display: grid;
grid-template-columns: 1fr 200px;
gap: 20px;
}
.box1 {
background-color: #fff000;
height: 200px;
}
.box2 {
background-color: #000;
height: 200px;
}