It is true that using outline: 0
or outline: none
will eliminate the blue outline when an element is focused.
This default styling is set by the browser's stylesheet and varies among different browsers.
However, it is important to consider accessibility when removing this focus indication. It is recommended to replace it with another visual cue to indicate that an element is in focus. Without this modification, navigating a site becomes much more challenging for users who rely on keyboards or other non-traditional methods of interaction.
In accordance with the html5 specification--
“…if an alternative focusing style isn’t made available instead, the page will be significantly less usable for people who primarily navigate pages using a keyboard, or those with reduced vision who use focus outlines to help them navigate the page.”
For more information, check out: Stop messing with the browsers default focus outline