Tangram

From NixOS Wiki

Tangram is a unique web browser that uses a set of persistent tabs. It is intended to be used for web applications instead of normal browsing.

dconf

By default, Tangram will be able to run, but is entirely crippled. The window cannot be resized, tabs cannot be added, and other major breakages occur. You will need to enable dconf in order to fix this.

programs.dconf.enable = true;