I Designed one applet. When i open that applet in Firefox on windows xp its showing good, But if same applet i open in Firefox on ubuntu/Linux , some text of applet showing Bigger font.
Different platforms may use different default fonts. If you want particular font sizes, make sure to set them explicitly. Also be aware that different machines/displays/operating systems use different DPI settings. Windows in particular uses a higher DPI, so fonts turn out being smaller than elsewhere.
The overall mission is to change the world. When you've done that, then you can read this tiny ad:
a bit of art, as a gift, that will fit in a stocking