Assertion:
Nested MARQUEE elements do not behave well in Internet Explorer.
Don't try it.
Basic nested MARQUEE elements, no widths on each. Green background on outer, yellow on inner:
filler text
filler text
Basic nested MARQUEE elements, width=500 on each. Green background on outer, yellow on inner:
filler text
outerMarquee
innerMarquee outerMarquee
filler text