Add the .navbar-btn class to <button> elements not residing in a <form> to vertically center them in the navbar.

<button type="button" class="btn btn-default navbar-btn">Sign in</button>

Context-specific usage

Like the standard button classes, .navbar-btn can be used on <a> and <input> elements. However, neither .navbar-btn nor the standard button classes should be used on <a> elements within .navbar-nav.

Related classes: