Hi,
You need to use css with a higher specifity to override inline css. In your drag & drop editor you right-click the element and click on inspect to find the right code to use.
Here you'll find an explanation of css specifity: https://dev.to/emmabostian/css-specificity-1kca
As an example, when you insert articles and you would like to change the color of the clickable article titles you use this code in your custom style sheet:
#acym__wysid__template h2 a, #acym__wysid__template h2 a:visited {color: #e8e8e8;}