[gnome-software] trivial: Fix the padding in the new hamburger menu

[Richard Hughes <rhughes src gnome org>]

commit 26c02f458ab2b3b495ce2134c525e1a24d1d46d0
Author: Richard Hughes <richard hughsie com>
Date:   Mon Jul 16 13:17:35 2018 +0100

    trivial: Fix the padding in the new hamburger menu

 src/gtk-style.css | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/gtk-style.css b/src/gtk-style.css
index c9bcbb01..9f111278 100644
--- a/src/gtk-style.css
+++ b/src/gtk-style.css
@@ -406,6 +406,10 @@ button.star, .button.star {
        outline-offset: -1px;
 }
 
+modelbutton {
+       padding: 3px;
+}
+
 /* i have no idea why GTK adds padding here */
 flowboxchild {
        padding: 0px;