The original prototype - http://pauginer.github.io/prototypes/notifications/notification-page/index.html:
Currently, the tabs and 'Mark as read' are bolded, but pagination labels are not.
In the original design, it's vice versa - the tabs and 'Mark as read' are not bolded and pagination labels are bold, which is illustrated in the screenshot below:
For the button and button groups we want to use the standard components which are currently using bold text.
We can revisit the standard components as part of UI-Standardization efforts if needed.