Should I connect both jquery-ui.js and jquery-ui.css files if the page looks fine with jquery-ui.js but without jquery-ui.css?
Should I care about jquery-ui.css?
P.S. jquery-ui.js is definitely needed for my slider, but the slider looks fine even without jquery-ui.css.
Thanks.
Yes, you should.
Most of the jQuery UI widgets depend on style rules defined in that file to perform their layout. Omitting it will give you strange bugs such as, for instance, dialog boxes not being properly rendered, or tabs and accordions not laying out correctly.