I chose the Solarized Light theme for this blog because it's designed for comfort. The low contrast and specific color palette are meant to be easy on the eyes, reducing strain during long reading sessions.
The theme is built on a set of 16 colors, 8 monotones and 8 accent colors. This light background is #fdf6e3, and the red "border" you see is #dc322f, one of the accent colors.
It's a classic theme among programmers and writers for a reason!