Hi @concentric
For reference, this issue isn't caused by being logged in. It's an issue with the viewport width.
When you're logged in, the config panel takes up space on the left, reducing the width of the preview window and everything looks great. When you're logged out you have a wider preview. As the width is increased, the nav folders are prevented from wrapping and you see this issue.
You should be able to correct it by adding the following (add it below the CSS I provided before):
.Header-nav {
white-space: normal;
}