Zathura

Zathura is an opensource hackable document viewer that allows complete control via the keyboard, instead of solely the mouse.

Themes

You can customize the colorschemes of the documentviewer including the border colors.

I found a fun little program to to generate themes from your wallpaper, here

The project is mainly focused on Linux, but there’s also some people maintaining a homebrew tap that will allow you to brew install it on macOS.

Currently there’s no way to hide the title bar on macOS, but it looks like it’s maybe being worked on here: homebrew zathura