HTML, CSS: grid
<!DOCTYPE html>
<html lang="en-US">
<meta charset="utf-8">
<head>
<title>Grid Test</title>
<style>
#grid {
display: grid;
/*width: 100%;*/
grid-template-columns: 400px 400px;
grid-template-rows: 210px 210px;
}
</style>
</head>
<body>
<div id="grid">
<div><img src="sf1.jpg"></div>
<div><img src="sf2.jpg"></div>
<div><img src="sf3.jpg"></div>
<div><img src="sf4.jpg"></div>
</div>
</body>
</html>