<html><body><p><b>Note:</b> This example only works in Firefox and Google Chrome.</p><svg xmlns="https://www.w3.org/2000/svg" version="1.1"> <rect x="20" y="20" width="250" height="250" style="fill:blue"> <animate attributeType="CSS" attributeName="opacity" from="1" to="0" dur="5s" repeatCount="indefinite" /> </rect></svg></body></html>