All the modules of the sidebar will have the same styling. We have options to change the styling of the sidebar under the "Sidebar tab" in TemplateToaster. And if you want to edit the styling of modules in the sidebar you can do it from the "Modules tab".
You can only change the width for the left and right sidebars separately from Sidebar tab=> Width option. All the other styling from the Sidebar tab will apply to all sidebars.