HTML provides the ability to embed UI styling attributes within individual HTML elements. Despite this feature being available, it is modern best practice to completely separate UI styling into separate CSS files. This separates functions and centralises UI styling into one place making it easier for example to upgrade the UI styling of a site independently of the page content and structure. Inline styles also have some particular problems in that they can degrade the page load performance of a page and unnecessarily complicate HTML code.
Inline Styles should be manually removed from the HTML code of a page and merged into separate CSS files, but may need the help of a designer to carefully consider their purpose and function.