Edit the file style.css found in the StyleFolder of your menu and
find the css class parentMenuContainer
. Modify the width and height properties of this css class to set
To make Text Menu fill the container where it is placed, set width or height to 100%
When setting dimensions, take into account that menu cannot be smaller than the dimensions
of the items (e.g. in Horizontal version of menu, if you set menu width to a value smaller than the space required for the items
to show, menu will use the closest witdh possible to your value to also allow all items to display).