IE6 is a dead browser, and Windows XP is an unsupported operating system.
At the time of writing, less than 4% of the world uses an outdated and unsupported browser in accordance with the Microsoft IE6 countdown. https://www.modern.ie/en-us/ie6countdown
I highly recommend that you do not waste time adding additional compatibility for such obsolete and practically unused technologies, except that your boss requires you to do this.
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