If a default stylesheet is applied by browsers, you can typically override it by specifying the appropriate style property and setting it to your desired value. However, some browsers may not use a default style sheet or may restrict your ability to modify settings.
Opting for a script-driven alternative is often not ideal. These alternatives tend to not accurately replicate default browser behavior and instead implement what the developer believes is best, potentially causing issues for users. For example, using keyboard navigation in Safari may be disrupted when a script-driven replacement select element only recognizes the tab key for selection, leading to a subpar user experience for some individuals.
Why alter the default browser settings? Is it truly necessary to remove highlighting? Users become accustomed to their browser's functionality, so introducing unnecessary changes to the UI can create confusion and frustration. Personally, I may not appreciate excessive highlighting triggered by cursor movement, but respecting the existing design choices tends to result in a smoother user experience overall.