Board Thread:Support Requests - Designing Your Wikia/@comment-26843745-20151103112952/@comment-5062941-20151103153315

Linking your wiki helps a lot so we can easily see the elements that's being used in your wiki-navigation :)

Anywho, from what I saw in your wiki the blue lines that are causing it are the:
 * background-color: #0C4BFF in
 * border-bottom: 1px solid #0038D8 in
 * border-top: 1px solid #0C4BFF in

These are most likely from the original theme of your wiki-navigation. You can set the hex values as transparent. (e.g. border-top: 1px solid transparent)

You may want to also just use  instead of calling each nth-child since you may be adding more tabs in wiki-navigation in the future.

I'm not too sure about centering the tabs in wiki-navi though. Someone else may come by and have a solution for it. :)