enter image description here

// Source - https://stackoverflow.com/q/18443546
// Posted by dzhioev
// Retrieved 2025-11-19, License - CC BY-SA 3.0

<svg id="svg-root" width="800" height="600"
  xmlns="http://www.w3.org/2000/svg"
  xmlns:xlink="http://www.w3.org/1999/xlink">
  <g id="test-body-content">
    <defs>
      <filter id="blur" filterUnits="userSpaceOnUse">
       <feGaussianBlur in="SourceGraphic" stdDeviation="10" result="blur" />
       <feMerge>
         <feMergeNode in="blur" />
       </feMerge>
      </filter>
    </defs>
    <rect x="50" y="50" width="200" height="100" fill="black" filter="url(#blur)"/>
  </g>
</svg>