Decrease height of title bar of apps without switching theme on Ubuntu 18.04

Solution 1:

The above did not work for me... but I got good results with the following in my file ~/.config/gtk-3.0/gtk.css :

 /*
 * Reduce height of window header (title?) bars.
 * Seems enough to specify padding, no need to repeat
 *   padding-left padding-right padding-top padding-bottom
 * nor it seems necessary to even mention
 *   margin-top margin-bottom
 */

.default-decoration {
    min-height: 0px;
    padding: 3px;
}

.default-decoration .titlebutton {
    min-height: 0px;
    padding: 0px;
}

Solution 2:

Assuming you are using Gnome 3 -

1. Open or Create the file : ~/.config/gtk-3.0/gtk.css (~ is the home location for your current user. For example, if your user is demo, then ~ would represent \home\demo)

2. Add the following CSS to the file

   headerbar entry,    
   headerbar spinbutton,    
   headerbar button,    
   headerbar separator {    
       margin-top: 0px; /* same as headerbar side padding for nicer proportions */    
       margin-bottom: 0px;    
   }    
   
   headerbar {    
       min-height: 24px;    
       padding-left: 2px; /* same as childrens vertical margins for nicer proportions */    
       padding-right: 2px;    
       margin: 0px; /* same as headerbar side padding for nicer proportions */    
       padding: 0px;    
   }    
   

3. Run ALT+F2 and provide the letter 'r' in the dialog box that appears that and hit enter to refresh the style

For more info, refer the original solution from Unix Stackexchange : https://unix.stackexchange.com/questions/276951/how-to-change-the-titlebar-height-in-standard-gtk-apps-and-those-with-headerbars?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa