My classes are located in sub-classes of previous elements

Hello!
I have such issue, which I realized only after making a long page:
After finishing “scroll bar" widget I started to create new sections with content, tabs and other.
Then, I realized that my sections are located inside of section “scroll bar" and all of my new classes go to the new sub-class.
How can I create classes individual after making a widget(scroll bar, tabs)
Thanks a lot!