tweak ssd borders

common/gtk-3.0/3.16/gtk-contained-dark.css

@@ -2345,7 +2345,7 @@ GtkVolumeButton.button {
     border-radius: 0; }
   .window-frame.ssd {
     border-radius: 3px 3px 0 0;
-    box-shadow: 0 0 0 1px rgba(31, 34, 39, 0.97); }
+    box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.65); }
     .window-frame.ssd.maximized {
       border-radius: 0; }
   .window-frame.csd.popup, .window-frame.csd.menu {

common/gtk-3.0/3.16/gtk-contained-darker.css

@@ -2346,7 +2346,7 @@ GtkVolumeButton.button {
     border-radius: 0; }
   .window-frame.ssd {
     border-radius: 3px 3px 0 0;
-    box-shadow: 0 0 0 1px rgba(31, 34, 39, 0.97); }
+    box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.65); }
     .window-frame.ssd.maximized {
       border-radius: 0; }
   .window-frame.csd.popup, .window-frame.csd.menu {

common/gtk-3.0/3.16/gtk-contained-solid-dark.css

@@ -2345,7 +2345,7 @@ GtkVolumeButton.button {
     border-radius: 0; }
   .window-frame.ssd {
     border-radius: 3px 3px 0 0;
-    box-shadow: 0 0 0 1px #1f2227; }
+    box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.65); }
     .window-frame.ssd.maximized {
       border-radius: 0; }
   .window-frame.csd.popup, .window-frame.csd.menu {

common/gtk-3.0/3.16/gtk-contained-solid-darker.css

@@ -2346,7 +2346,7 @@ GtkVolumeButton.button {
     border-radius: 0; }
   .window-frame.ssd {
     border-radius: 3px 3px 0 0;
-    box-shadow: 0 0 0 1px #1f2227; }
+    box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.65); }
     .window-frame.ssd.maximized {
       border-radius: 0; }
   .window-frame.csd.popup, .window-frame.csd.menu {

common/gtk-3.0/3.16/sass/_common.scss

@@ -2717,7 +2717,7 @@ GtkVolumeButton.button { padding: 8px; }
   // server-side decorations as used by mutter
   &.ssd {
     border-radius: if($darker=='false' and $variant=='light', 4px 4px 0 0, 3px 3px 0 0);
-    box-shadow: 0 0 0 1px if($darker=='true' or $variant == 'dark', darken($header_bg, 7%), $_wm_border);
+    box-shadow: 0 0 0 1px if($darker=='true' or $variant == 'dark', transparentize(black, 0.35), $_wm_border);
 
     &.maximized { border-radius: 0; }
   }