This is an example of the Navigation on Top header option. Solstice comes with multiple header layout options–choose the one that works best for you! The header option is part of the WordPress Customizer, so you can preview how each option looks before committing to it.
The header options are as follows (click each image to see a preview of how it will look):

Logo on Top

with the Navigation below

Navigation on Top

with the Logo below

Single Row

with the Logo on the Left and the Navigation on the Right