Removed 1px margin for general buttons, allowing xfce panel to take advantage of the rule of infinite edges and magic corners in Fitt's Law

source/common/buttons.scss

@@ -25,7 +25,7 @@
         &:active, &.keyboard-activating {
             @include _shadows($button_shadow_pressed);
         }
-        &:checked, &:selected, &.has-open-popup { //selected and has-open-popup is for .activatable rows, hopefully it won't go wrong
+        &:checked, &:selected, &.has-open-popup, %button-pressed { //selected and has-open-popup is for .activatable rows, hopefully it won't go wrong
             background-color: $c_pressed;
             color: $tc_pressed;
             @include _shadows($button_shadow_pressed, 0 10px 3px -9px gtkalpha(currentColor, 0.3)); //, 0 -3px 2px -2px gtkalpha(currentColor, 0.2) //a highlight on the upper border, maybe not for now, because it's harder to make it look realistic...
@@ -38,6 +38,7 @@
                 @include _shadows($button_shadow_pressed, 0 10px 3px -9px gtkalpha(currentColor, 0.5));
                 }
         }
+         
     }
     &:disabled {
         &, &:checked, &:selected, &.has-open-popup {

source/common/desktop_environment_fixes.scss

@@ -0,0 +1,16 @@
+
+// XFCE system tray buttons don't look good without margin
+.xfce4-panel #sn-button {
+  margin: 1px;
+}
+
+#docklike-plugin {
+    button {
+        background-color: transparent;
+        .active_group & {
+            @extend %button-pressed;
+            background-color: red;
+        }
+    }
+    
+}

source/gtk3/_common.scss

@@ -585,7 +585,7 @@ button {
     border: $button_border;
     border-radius: $button_radius;
     transition: $button_transition;
-    margin: 1px;
+    margin: 0px; //1px;
 
     @include button();
 
@@ -3265,3 +3265,5 @@ popover.emoji-completion .emoji:hover {
 @import '../common/undershoot.scss';
 
 @import '../common/stack_switcher.scss';
+
+@import '../common/desktop_environment_fixes.scss'

source/gtk4/_common.scss

@@ -491,7 +491,7 @@ button {
     border: $button_border;
     border-radius: $button_radius;
     transition: $button_transition;
-    margin: 1px;
+    margin: 0px; //1px;
 
     @include button();
 
@@ -3285,3 +3285,4 @@ menubutton {
 
 @import '../common/undershoot.scss';
 @import '../common/stack_switcher.scss';
+@import '../common/desktop_environment_fixes.scss'