how to style menu

The categories are listing properly in the space designated by my joomla template. It is a column 150px wide.
But---they are being listed in 2 columns and all I want is a list with no images. (I could live with the images part, but I really just want a list with the words written out horizontally with no word wrap.) The little containers for the category names are tall and narrow. I want them as wide as the 150px column.
Where should I look to change the styling?

Addendum: Now that I look more closely, I think that my listing of categories is supposed to appear in the larger component area in my template. What I want is the list type of menu in the narrow column. I just looked at some support documentation and realized I need to make a separate menu for the category items. That would answer my question!

You can build a standard joomla menu and then when you add the hikashop items choose type = product page > select a product, assuming you wish to display a single item.

If you're using the hikashop content module you could change the 'Type of layout' to 'list' rather than 'div'.