Lawyers Attorneys Legal Office Responsive Theme Help Desk

In order to decrease the gallery size in a single portfolio view, please add this to the Custom CSS area in Dashboard > Vamtam > General:

.portfolio-image-wrapper > .bxslider-wrapper { max-width: 600px; margin: auto;}

Adjust the bold number.

Here's a guide how to add the code: 

http://support.vamtam.com/solution/articles/200025-how-to-add-custom-css-code-