Monitors differ on resolution. I've tried to keep enough information at the top of the screen as possible so that the user can decide whether or not to look at the rest. This has not always been possible. And in turn 1024x768 shows even more. What fills the screen at one resolution might become uncomfortably small at another.
Browsers differ as to how they display color.
Netscape allows hundreds of thousands of colors in its backgrounds. Early Microsoft browsers allowed only a few. I've tried to use standard web-safe colors where possible. What seems to be a grainy and dithered image on an 8 bit display might seem fantastically beautiful on a 24-bit display. I've tried to make everything at least viewable on an 8-bit display.