Simplenotes is a free theme for WordPress created by Carla Izumi Bamford.
Simplenotes is a clean and minimal WordPress theme that requires no plugins to run. The theme features a dropdown menu, social media integration, sidebar widgets, threaded comments, theme option page, and more. The simple notebook is ready for both writers and readers.
(Description "Simplenotes" Theme from wordpress.org)
You can download Simplenotes for free via the provided download link and include it into your themes folder of your WordPress installation. Also you can directly search for it in the WordPress admin interface in the themes section and install and activate it from there.
More information, screenshots and reviews of Simplenotes Theme can be found here.