Block Quote Problem

I’m having a bit of trouble. I organized my block quotes the way I liked them via the CSS stylesheet, but I’ve seen my website on my girlfriend’s and my mom’s computer, and they look entirely different. Normally the blockquote is just set apart with quotes around it, but on other computers, it’s got weird colored blocks around it, and the text within the blocks are surrounded by another color.

If that sounds confusing, just take a look at my website: http://www.trialofthecentury.net. If the block quotes look ugly to you, you’re seeing it!

Is there any way I can make my CSS changes apply to the website on both my computer and other peoples’ computers?