Eradicate CSD eyesore with gtk3-nocsd
If you have been using Linux, you have probably noticed that some programs have windows with fat, ugly, extraneous-looking title bars. These are client-side decorations, an anti-feature of GTK widget toolkit. There is, however, a way to get rid of this deformity, and that is gtk3-nocsd module. Note that it doesn't work on Wayland, only on X11.
After installing gtk3-nocsd, restart graphical session. Ugly header bars are no more.
Available as video here