https://stackoverflow.com/questions/19733447/bootstrap-navbar-with-left-center-or-right-aligned-items
https://stackoverflow.com/questions/41513463/bootstrap-4-align-navbar-items-to-the-right
https://www.codeply.com/go/kTGlK9Axdk
bootstrap navbar items alignment
原文：https://www.cnblogs.com/hong2016/p/9194236.html