            <fePointLight x="60" y="60" z="20" />
        </feDiffuseLighting>
    </filter>

    <rect x="0" y="0" width="200" height="200" style="filter: url(#diffuseLighting);" />
</svg>

<svg viewBox="-1 -1 162 92" xmlns="http://www.w3.org/2000/svg">
    <defs>
        <path id="smiley" d="M50,10 A40,40,1,1,1,50,90 A40,40,1,1,1,50,10 M30,40 Q36,35,42,40 M58,40 Q64,35,70,40 M30,60 Q50,75,70,60 Q50,75,30,60" />
    </defs>

    <!-- (width>height) meet -->
    <rect x="0" y="0" width="20" height="10">
   