when blogging on wordpress. my blog destroys the template i created. how to avoid that?

here is the site im talking about. http://marillest.com/?d=1 (make sure to include the ?d=1)

i had set up a simple design with width specifications through css but when i start blogging and place large images within the area the entire design gets messed up. things go all over the place. how can i stop this? this website is for a client of mine and they dont know much css or anything and will be working throuhg design view开发者_Go百科 in the wordpress blogging section. anyone know?

thanks

You've got an extra </div> tag that's probably causing problems, according to W3C validation: [Invalid] Markup Validation of marillest.com - W3C Markup Validator