I see that the jquery UI distribution contains 15 css files. The jquery.ui.all.css file contains two @import statements — one for jquery.ui.base.css and another for jquery.ui.theme.css.
The jquery.ui.base.css itself contains 11 import statements for jquery.ui.core.css and then each of the widgets.
I also see a single (larger than others in the folder) file called jquery-ui.css.
Am I off in thinking that if I want all the CSS for a given theme then linking the single jquery-ui.css works but if I want to customize the pieces that I download then importing jquery.ui.all.css and customizing jquery.ui.base.css is the way to go?
Am I not understanding something?
You should use the jquery-ui.css. If you don’t need certain widgets, you can uncheck them when making your (custom) jQuery UI and they won’t be included.