gtk3, gtk4: make comboboxes look more true to breeze qstyle

src/gtk3/widgets/_button.scss

@@ -444,11 +444,16 @@ button {
  **************/
 combobox {
   arrow {
-    -gtk-icon-source: -gtk-icontheme("pan-down-symbolic");
+    -gtk-icon-source: -gtk-icontheme('go-down-symbolic');
     min-height: 16px;
     min-width: 16px;
   }
 
+  button {
+    padding-top: 4px;
+    padding-bottom: 4px;
+  }
+
   &.linked {
     button:nth-child(2) {
       &:dir(ltr) {

src/gtk4/widgets/_button.scss

@@ -405,11 +405,16 @@ button {
  * ComboBoxes *
  **************/
  combobox {
-   arrow {
-     -gtk-icon-source: -gtk-icontheme('pan-down-symbolic');
-     min-height: 16px;
-     min-width: 16px;
-   }
+  arrow {
+    -gtk-icon-source: -gtk-icontheme('go-down-symbolic');
+    min-height: 16px;
+    min-width: 16px;
+  }
+
+  button {
+    padding-top: 4px;
+    padding-bottom: 4px;
+  }
 
    &.linked {
      button:nth-child(2) {