How to expand the dropdown menu into four columns?

[aquatic_living1]

Hi! Can somebody help me how to change the layout of the dropdown menu for my site https://aquaticliving.co.uk/

Currently, the dropdown for "Brands" is in one column only, so I can't see all the brands below because they are all stacked in a single column. You can see the attached image to see what I'm referring to.

 

I want it to be like the dropdown of https://www.swelluk.com/ where they have four columns on it. Sample on the picture below

 

[MustafA16]

hey @aquatic_living1  i will be do this for you if you want me to do this then ?

[aquatic_living1]

sure, just let me know what the right CSS I should I use and where to put them

[MustafA16]

hey @aquatic_living1  first of there is no css to do this work 

so if you want me to do this 

in to this 

then ?