UI: Fix extra browsers trash icon

The trash icon in the extra browsers dock would be rendered
incorrectly with the Yami based themes.

UI/data/themes/Acri.qss

@@ -1169,6 +1169,8 @@ VisibilityCheckBox::indicator:unchecked:hover {
 
 QPushButton#extraPanelDelete {
     background-color: palette(mid);
+    margin: 0;
+    padding: 0;
 }
 
 QPushButton#extraPanelDelete:hover {

UI/data/themes/Grey.qss

@@ -1158,6 +1158,8 @@ VisibilityCheckBox::indicator:unchecked:hover {
 
 QPushButton#extraPanelDelete {
     background-color: palette(mid);
+    margin: 0;
+    padding: 0;
 }
 
 QPushButton#extraPanelDelete:hover {

UI/data/themes/Light.qss

@@ -1158,6 +1158,8 @@ VisibilityCheckBox::indicator:unchecked:hover {
 
 QPushButton#extraPanelDelete {
     background-color: palette(mid);
+    margin: 0;
+    padding: 0;
 }
 
 QPushButton#extraPanelDelete:hover {

UI/data/themes/Rachni.qss

@@ -1162,6 +1162,8 @@ VisibilityCheckBox::indicator:unchecked:hover {
 
 QPushButton#extraPanelDelete {
     background-color: palette(mid);
+    margin: 0;
+    padding: 0;
 }
 
 QPushButton#extraPanelDelete:hover {

UI/data/themes/Yami.qss

@@ -1162,6 +1162,8 @@ VisibilityCheckBox::indicator:unchecked:hover {
 
 QPushButton#extraPanelDelete {
     background-color: palette(mid);
+    margin: 0;
+    padding: 0;
 }
 
 QPushButton#extraPanelDelete:hover {