diff --git a/common/gtk-3.0/3.20/gtk-dark.css b/common/gtk-3.0/3.20/gtk-dark.css
index 8489723..47ec269 100644
--- a/common/gtk-3.0/3.20/gtk-dark.css
+++ b/common/gtk-3.0/3.20/gtk-dark.css
@@ -1638,6 +1638,14 @@ notebook {
     border: 1px solid #2b2e39; }
     notebook.frame > header {
       margin: -1px; }
+      notebook.frame > header.top {
+        margin-bottom: 0; }
+      notebook.frame > header.bottom {
+        margin-top: 0; }
+      notebook.frame > header.left {
+        margin-right: 0; }
+      notebook.frame > header.right {
+        margin-left: 0; }
       notebook.frame > header.top, notebook.frame > header.bottom {
         padding-left: 0;
         padding-right: 0; }
diff --git a/common/gtk-3.0/3.20/gtk-darker.css b/common/gtk-3.0/3.20/gtk-darker.css
index 5119abc..293486e 100644
--- a/common/gtk-3.0/3.20/gtk-darker.css
+++ b/common/gtk-3.0/3.20/gtk-darker.css
@@ -1637,6 +1637,14 @@ notebook {
     border: 1px solid #dcdfe3; }
     notebook.frame > header {
       margin: -1px; }
+      notebook.frame > header.top {
+        margin-bottom: 0; }
+      notebook.frame > header.bottom {
+        margin-top: 0; }
+      notebook.frame > header.left {
+        margin-right: 0; }
+      notebook.frame > header.right {
+        margin-left: 0; }
       notebook.frame > header.top, notebook.frame > header.bottom {
         padding-left: 0;
         padding-right: 0; }
diff --git a/common/gtk-3.0/3.20/gtk-solid-dark.css b/common/gtk-3.0/3.20/gtk-solid-dark.css
index bf7f92a..5354f23 100644
--- a/common/gtk-3.0/3.20/gtk-solid-dark.css
+++ b/common/gtk-3.0/3.20/gtk-solid-dark.css
@@ -1638,6 +1638,14 @@ notebook {
     border: 1px solid #2b2e39; }
     notebook.frame > header {
       margin: -1px; }
+      notebook.frame > header.top {
+        margin-bottom: 0; }
+      notebook.frame > header.bottom {
+        margin-top: 0; }
+      notebook.frame > header.left {
+        margin-right: 0; }
+      notebook.frame > header.right {
+        margin-left: 0; }
       notebook.frame > header.top, notebook.frame > header.bottom {
         padding-left: 0;
         padding-right: 0; }
diff --git a/common/gtk-3.0/3.20/gtk-solid-darker.css b/common/gtk-3.0/3.20/gtk-solid-darker.css
index 1c0d544..d4f57b1 100644
--- a/common/gtk-3.0/3.20/gtk-solid-darker.css
+++ b/common/gtk-3.0/3.20/gtk-solid-darker.css
@@ -1637,6 +1637,14 @@ notebook {
     border: 1px solid #dcdfe3; }
     notebook.frame > header {
       margin: -1px; }
+      notebook.frame > header.top {
+        margin-bottom: 0; }
+      notebook.frame > header.bottom {
+        margin-top: 0; }
+      notebook.frame > header.left {
+        margin-right: 0; }
+      notebook.frame > header.right {
+        margin-left: 0; }
       notebook.frame > header.top, notebook.frame > header.bottom {
         padding-left: 0;
         padding-right: 0; }
diff --git a/common/gtk-3.0/3.20/gtk-solid.css b/common/gtk-3.0/3.20/gtk-solid.css
index 3c6bb05..f920d12 100644
--- a/common/gtk-3.0/3.20/gtk-solid.css
+++ b/common/gtk-3.0/3.20/gtk-solid.css
@@ -1641,6 +1641,14 @@ notebook {
     border: 1px solid #dcdfe3; }
     notebook.frame > header {
       margin: -1px; }
+      notebook.frame > header.top {
+        margin-bottom: 0; }
+      notebook.frame > header.bottom {
+        margin-top: 0; }
+      notebook.frame > header.left {
+        margin-right: 0; }
+      notebook.frame > header.right {
+        margin-left: 0; }
       notebook.frame > header.top, notebook.frame > header.bottom {
         padding-left: 0;
         padding-right: 0; }
diff --git a/common/gtk-3.0/3.20/gtk.css b/common/gtk-3.0/3.20/gtk.css
index 906cf51..3b87665 100644
--- a/common/gtk-3.0/3.20/gtk.css
+++ b/common/gtk-3.0/3.20/gtk.css
@@ -1641,6 +1641,14 @@ notebook {
     border: 1px solid #dcdfe3; }
     notebook.frame > header {
       margin: -1px; }
+      notebook.frame > header.top {
+        margin-bottom: 0; }
+      notebook.frame > header.bottom {
+        margin-top: 0; }
+      notebook.frame > header.left {
+        margin-right: 0; }
+      notebook.frame > header.right {
+        margin-left: 0; }
       notebook.frame > header.top, notebook.frame > header.bottom {
         padding-left: 0;
         padding-right: 0; }
diff --git a/common/gtk-3.0/3.20/sass/_common.scss b/common/gtk-3.0/3.20/sass/_common.scss
index 2fddf4e..bf4aef9 100644
--- a/common/gtk-3.0/3.20/sass/_common.scss
+++ b/common/gtk-3.0/3.20/sass/_common.scss
@@ -1735,7 +1735,12 @@ notebook {
     border: 1px solid $borders_color;
 
     > header {
-      margin: -1px;  // ugly hack to hide the borders around the header
+      // ugly hack to hide the borders around the header
+      margin: -1px;
+      &.top { margin-bottom: 0; }
+      &.bottom { margin-top: 0; }
+      &.left { margin-right: 0; }
+      &.right { margin-left: 0; }
 
       &.top, &.bottom { padding-left: 0; padding-right: 0; }
       &.left, &.right { padding-top: 0; padding-bottom: 0; }