~ via Unix Stackexchange
Gnome title bars can be tweaked using a simple css file. Creating a gtk.css file inside of ~/.config/gtk-3.0 with the following styles can scale down those awful thick/tall title bars.
Title bar height before tweaking
The CSS in gtk.css
/* shrink headerbars */
headerbar {
min-height: 0px;
// same as childrens vertical
// margins for nicer proportions
padding-left: 2px;
padding-right: 2px;
background-color: #2d2d2d;
}
headerbar entry,
headerbar spinbutton,
headerbar button,
headerbar separator {
// same as headerbar side padding
// for nicer proportions
margin-top: 0px;
margin-bottom: 0px;
}
/* shrink ssd titlebabbrs */
.default-decoration {
// let the entry and button
// drive the titlebar size
min-height: 0;
padding: 0px;
background-color: #2d2d2d;
}
.default-decoration .titlebutton {
// tweak these two props
// to reduce button size
min-height: 0px;
min-width: 0px;
}
window.ssd headerbar.titlebar {
padding: 3px;
padding: 3px;
min-height: 0;
}
window.ssd headerbar.titlebar
button.titlebutton {
padding: 3px;
padding: 3px;
min-height: 0;
}
Title bar height after tweaking
After saving the file, run alt + f2 and type r in the dialog box to restart the session and see the changes take effect.