<svg xmlns="http://www.w3.org/2000/svg" style="width: 400px; height: 400px;">
    <defs>
        <filter id="drop-shadow" x="-20%" y="-20%" width="150%" height="150%">
            <feDropShadow stdDeviation="20"/>
        </filter>
    </defs>
    <circle cx="150" cy="150" r="100" fill="white" filter="url(#drop-shadow)"/>
    <circle cx="150" cy="150" r="124" fill="green"/>
</svg>