Comment 0 for bug 1799663

In Ubuntu 18.04 (bionic) in Gnome Flashback(Metacity) session headerbars have too big size in Ambiance and Radiance theme.

I have resolved this problem by setting in gtk-widgets.ccs file`s section - .titlebar button .titlebutton - padding: 0;

.titlebar button.titlebutton {
    background-clip: padding-box;
    color: #3d3c37;
    -gtk-icon-shadow: 0 1px rgba(255, 255, 255, 0.1);
    box-shadow: none;
    border: none;
    padding-left: 0;
    padding-right: 0;
    margin: 0;

    padding: 0px; <-------here
    min-width: 20px;
    min-height: 20px;
    background-size: 20px 20px;
    background-image: -gtk-scaled(url("assets/windowbutton.png"),
                                  url("assets/windowbutton@2.png"),
                                  url("assets/windowbutton@3.png"),
                                  url("assets/windowbutton@4.png"));
    background-repeat: no-repeat;
    background-position: center;
}

As I have seen in light-themes(14.04+16.04.20180326-0ubuntu1) padding: 0; - exists in Ambiance and Radiance theme.

.titlebar.header-bar .button.titlebutton {
    background-clip: padding-box;
    border: 1px solid #383734;
    color: #3d3c37;
    icon-shadow: 0 1px rgba(255, 255, 255, 0.1);
    border-radius: 9px;
    padding: 0; <------here
    box-shadow: none;
    background-image: linear-gradient(to top, #5a5955, #75746d 50%, #8e8d88);
}

My OS is:
Description: Ubuntu 18.04.1 LTS
Release: 18.04

Package: light-themes
Version: 16.10+18.04.20180421.1-0ubuntu1
Priority: optional
Section: gnome
Source: ubuntu-themes
Origin: Ubuntu
Maintainer: Ubuntu Artwork Team <email address hidden>
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Installed-Size: 17,7 MB
Depends: gtk2-engines-murrine (>= 0.90.3+git20100810), humanity-icon-theme, ubuntu-mono
Homepage: https://launchpad.net/ubuntu-themes
Task: ubuntu-desktop, ubuntukylin-desktop
Supported: 5y
Download-Size: 458 kB
APT-Manual-Installed: no
APT-Sources: http://archive.pls.pbank.com.ua/ubuntu-current bionic/main i386 Packages
Description: Light Themes (Ambiance and Radiance)