Interesting, I don't see that here. I wonder if they're A / B testing layouts and my IP is locked into a specific choice.
If I open the page in Chrome or Firefox I see both buttons side by side and then if I slowly make the window smaller (starting at 2560 width btw), it eventually gets to the point where both buttons disappear inside of the hamburger menu when the buttons get too close to the left nav. The sign up button is never visible on its own.
Which browser do you use?
