Styling - themes - sc_bootstrap

I have reached a point where I have successfully made a number of changes to the styling by editing\adding properties to my theme file.

But I am struggling with a couple of things where the property is coming from the sc_bootstrap.css

eg the Login Button colour - Chrome tells me that the rule is coming from line 2577 of the sc_bootstrap file - and if I directly edit the rule at that line - yes it is shown on my page.

But - but if I copy the rule and paste it to my theme file - reset the sc_bootrap back to original - the site still looks to the bootstrap (Even if I use the !important rule)

I think I have missed something simple - but I cant see what.

What is the right way of modifying rules that originate from the sc_bootstrap stylesheet?

Mea Culpa - - - - - - I made a very simple mistake - and then failed to see my introduced error. <oops>

I had deleted a closing brace on an element just before the entries I was working on. Of course this made the file beyond that point just useless text.

Sometimes taking a break to step away - - - and or a quick check with a CSS validation tool Helps you see the obvious.

Many thanks for the response - and for creating this very useful addition to Joomla.