CSS not taking effect?

Anyone know what’s up with changing the CSS? I followed the instructions on the main page of the plugin and altered responsive-tooltip.css. The changes didn’t take effect. For good measure I put the same CSS changes into responsive-tooltip.org.css, which is also part of the plugin and has the same structure as the main CSS file. The changes still didn’t take. So I put the whole CSS directly into my theme options. That worked. I’d prefer that they don’t stay there, however. Duplication of CSS content. Bloat.

https://wordpress.org/plugins/responsive-mobile-friendly-tooltip/