right justify the last item in the header nav, FIVE theme

Hello, I am using theme FIVE and I'd like to move the last or rightmost link in the header nav (BUY THE BOOK, which I have styled like a button) to the right side of the page and have all the rest remain left justified (in the desktop view).  How would I do this with code?

Can you share site url? We can check easier.

thank you -https://*****

Add to Home > Design > Custom CSS

.horizontal-navigation-bar nav {
    width: 70%;
}
.horizontal-navigation-bar nav ul>li:last-child {
    float: right;
}

Awesome, that did it! Thank you.