child theme frustrations

I’m new to child themes. I’m obviously doing something wrong with either my container or content coding. Or something else. I’m trying to set a left margin in the content however whatever I do has no affect.

Also, I want to replace all #ff4b33 with #740000. That too is not working. Is there an easier, or correct, way to do this than what I have done?

Can someone check my code?

https://www.chrisquilts.net/blog

(It’s important to include the /blog, since this is a different WP than the rest of the site)