Textfield

Textfield

Screenshot of what this textfield looks like when it's in-focus (click inside the textfield) in the Chrome browser if no other styling has been specified:

This styling is different for different browsers. It's not caused by a stylesheet I or Wikia have written, it seems built in to the browser.

How do I
 * 1) Find out what the styling even is? I've looked up and down in Developer Tools and I'm still not sure where exactly I should look, or what CSS selectors I should be looking for. Right-click and "inspect element" didn't seem to be helpful... I see "user agent stylesheet" next to a few of the styles, so I think that might be what I'm looking for, but I'm not exactly sure. Does "user agent" = a web browser?
 * 2) Is it possible to override the browser's default styling? If I can just figure out what styles are affecting this text field, I'd like to try overriding them with my own custom styles by using more specific / higher priority CSS selectors.

Screenshot
How to find :focus styles in Chrome: