Disabling Responsive Design

I am a software developer and I use RapidWeaver to do my website and help pages for my programs. I get pretty good results with RapidWeaver, but there is a lot of friction in the workflow. Specifically, when I do my help pages I just want to type in the words. With my help pages, I am willing to sacrifice some styling that I get from RapidWeaver. This has put me on a search to find a tool that can satisfy my needs for creating help pages. Here’s what I require. I need to be able to create fixed width pages that automatically center themselves. I have two problems with Blocs.

First, turning off the responsive design. I know it is designed with responsive design as its foundation, but having the output rearrange itself every time the user resizes the help window is a poor user experience since we are only on a desktop. Is there a way to effectively turn off the responsive design? I have had partial success with changing class attributes.

Second, is there a way to set up a page to be centered? Is there code I can insert into the header for the page? I’m not a CSS expert, but if I can insert code in one place that would be acceptable.

If these two problems can be solved and not be a constant tedious effort, Blocs looks like it could be the solution for me.