If you're using Cloudflare, they will cache your CSS for a long time. This means that if you make changes to your CSS, it will take a while before seeing them on the live site.
The canonical way of dealing with this is to change the HTML to include a query parameter at the end of your link to the CSS. Even though your server will ignore the query parameter, every time you change its value it will cause Cloudflare to re-query your server for content, and will then cache the new version.
You can read more about the strategy here: https://css-tricks.com/strategies-for-cache-busting-css/.