No style defined for mission statement

I will be using the mission statement for an introduction for my site. However when enabling this there is no defined style for this. This results in the mission statement running over the boundaries of the other content. I have tried to edit the style sheet (changed "blockquote" to "#mission") but this resulted in a gray box which was partially hidden behind the blocks in the left sidebar.

My CSS knowledge stops about there, so can there be a style defined for theming and positioning the mission statement?

Best regards,
Marcel