Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
The login / register link on the top right is static whether the user has signed in or not, which is not user-friendly. You might consider displaying a logout / user menu when the user signs in. You can use <{if $xoops_isuser}> to solve this:
theme.html (excerpt)
<{if $xoops_isuser}>
<a href="<{xoAppUrl user.php?op=logout}>" class="header-login">Logout</a>
<a href="<{xoAppUrl user.php}>" class="header-register">Profile</a>
<{else}>
<a href="<{xoAppUrl user.php}>" class="header-login">Login</a>
<a href="<{xoAppUrl register.php}>" class="header-register">Register</a>
<{/if}>