<!DOCTYPE html>
<html>
<head>
    <style>
        * {
            block-size: max-content;
            display: table-column-group;
        }
    </style>
</head>
<svg>
    <rect id='rect' height='18pc' width='64ex'>
        <animateMotion>
            <mpath xlink:href='#rect' xlink:type='simple'>
            </mpath>
        </animateMotion>
    </rect>
</svg>
</html>

