Yes and you could find out by inspecting the site with the browser developer tools
They are from left to right #custom_html-3, #custom_html-2, #custom_html-4, #custom_html-6
But if you want to change the relative start and end in the middle, you should do that by changing the respective width of the columns in the theme Custom widget width settings.
Right now you have the widget width set at 30% – 30% – 20% – 20%
By changing these values, you will shift the start of each column.