Fixing body widths with horizontal lists

[matturn]

I have a horizontal list. Every popularish browser except Safari doesn't see it when determining the minimum width of the body (the whole area available to scroll to, not the viewport).

If I give the UL (or another encompassing object) a set pixel width, that will be "seen" and sufficient body width will exist for the LIs to no longer be in a nice horizontal row. But what is the best practice for this situation?

[matturn]

I meant to say that giving an encompassing object a fixed width will allow the LIs to remain in a row.