560 bytes css grid.
<!DOCTYPE HTML>
<head>
<link rel="stylesheet" href="mini.css"/>
</head>
<html>
<body>
<div class="container">
<div class="r1 left">R1</div>
<div class="r11 right">R11</div>
</div>
<div class="container">
<div class="r2 left">R2</div>
<div class="r10 right">R10</div>
</div>
</body>
</html