Why Your Custom CSS Doesn’t Work in WordPress and … – Media Temple
Occasionally, you may find that, when you add custom CSS to your website, it just doesn’t seem to get applied correctly. There’s a lot of reasons why this might be the case, but the primary one is the heart of the “C” in CSS’s full name (“Cascading Style Sheets”) and how WordPress enqueues your stylesheets onto your site. We’ll walk through those basics so you understand what’s happening, how to diagnose the issue, and how to resolve it.
What’s Happening
Here’s an example. Let’s say you have a child theme [AR1] and you have a plugin that has its own stylesheet. For this example, let’s call it “Reaction Buttons”. If you were to activate that plugin and then try to override the styles in your child theme, you’ll notice that it simply doesn’t work.
There is a technical explanation: The plugin is enqueueing its corresponding stylesheet with the wrong action. But the outcome is that the stylesheet is added later in your page
You see, that’s the “Cascading” part of “Cascading Style Sheets”,
Source: https://managewp.org/articles/13984/why-your-custom-css-doesn-t-work-in-wordpress-and-media-temple
source https://williechiu40.wordpress.com/2016/12/08/why-your-custom-css-doesnt-work-in-wordpress-and-media-temple/