我在 Ubuntu 18.04 i386 中安装了 LibreOffice 6.03。当我单击它的菜单项时，它的启动窗口会弹出，但不久之后它就消失了。当我从 shell 窗口中的命令行启动它时，它也会执行相同的操作，但 shell 窗口会显示以下消息：
(soffice:11972): Gtk-WARNING **: 20:12:48.560: Theme parsing error: gtk.css:27:35: Junk at end of value for background-color
(soffice:11972): Gtk-WARNING **: 20:12:48.560: Theme parsing error: gtk.css:40:48: Junk at end of value for background-color
(soffice:11972): Gtk-WARNING **: 20:12:48.560: Theme parsing error: gtk.css:48:46: Junk at end of value for background-color
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:59:58: Junk at end of value for background-color
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:66:28: The :prelight pseudo-class is deprecated. Use :hover instead.
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:70:46: Junk at end of value for background-color
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:77:35: The :prelight pseudo-class is deprecated. Use :hover instead.
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:81:58: Junk at end of value for background-color
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:123:31: The :insensitive pseudo-class is deprecated. Use :disabled instead.
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:124:24: The :insensitive pseudo-class is deprecated. Use :disabled instead.
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:156:27: The :insensitive pseudo-class is deprecated. Use :disabled instead.
(soffice:11972): Gtk-WARNING **: 20:12:48.561: Theme parsing error: gtk.css:157:29: The :insensitive pseudo-class is deprecated. Use :disabled instead.
(soffice:11972): Gtk-WARNING **: 20:12:48.562: Theme parsing error: gtk.css:177:34: The :insensitive pseudo-class is deprecated. Use :disabled instead.
(soffice:11972): Gtk-WARNING **: 20:12:48.562: Theme parsing error: gtk.css:199:34: The :inconsistent pseudo-class is deprecated. Use :indeterminate instead.
如何修复？