Can C17 look like C6

In 2017, Dreamweaver CC was re-built  with a new UI and code editor based on Brackets.  It's not possible to roll back to the old UI unless you revert to CS6. 

Personally,  I'm not a huge fan of CSS Designer panels.   I think  code hints and auto code completion makes working directly with code a lot more efficient than panels. 

NEVER edit Bootstrap CSS code.  That should be a read only file and off limits to you.  If you require custom styles and you don't yet know how to work with SASS/SCSS, then use a separate external stylesheet.