diff --git a/docs/reference/gtk/gtk3-sections.txt b/docs/reference/gtk/gtk3-sections.txt
index 6ee269d954..3fdfeed9d7 100644
--- a/docs/reference/gtk/gtk3-sections.txt
+++ b/docs/reference/gtk/gtk3-sections.txt
@@ -5652,6 +5652,10 @@ GTK_STYLE_CLASS_VIEW
 GTK_STYLE_CLASS_WARNING
 GTK_STYLE_CLASS_HORIZONTAL
 GTK_STYLE_CLASS_VERTICAL
+GTK_STYLE_CLASS_TOP
+GTK_STYLE_CLASS_BOTTOM
+GTK_STYLE_CLASS_LEFT
+GTK_STYLE_CLASS_RIGHT
 GTK_STYLE_REGION_COLUMN
 GTK_STYLE_REGION_COLUMN_HEADER
 GTK_STYLE_REGION_ROW
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index f5f90093b6..97e9f307f2 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -222,7 +222,11 @@
  * #GTK_STYLE_CLASS_QUESTION,
  * #GTK_STYLE_CLASS_ERROR,
  * #GTK_STYLE_CLASS_HORIZONTAL,
- * #GTK_STYLE_CLASS_VERTICAL.
+ * #GTK_STYLE_CLASS_VERTICAL,
+ * #GTK_STYLE_CLASS_TOP,
+ * #GTK_STYLE_CLASS_BOTTOM,
+ * #GTK_STYLE_CLASS_LEFT,
+ * #GTK_STYLE_CLASS_RIGHT,
  * </para>
  * <para>
  * Widgets can also add regions with flags to their context.
diff --git a/gtk/gtkstylecontext.h b/gtk/gtkstylecontext.h
index 3e32c683cb..33cf5560fa 100644
--- a/gtk/gtkstylecontext.h
+++ b/gtk/gtkstylecontext.h
@@ -600,6 +600,45 @@ struct _GtkStyleContextClass
  */
 #define GTK_STYLE_CLASS_VERTICAL "vertical"
 
+/**
+ * GTK_STYLE_CLASS_TOP:
+ *
+ * A CSS class to indicate an area at the top of a widget.
+ *
+ * This is used by widgets that can render an area in different
+ * positions, such as tabs in a #GtkNotebook.
+ */
+#define GTK_STYLE_CLASS_TOP "top"
+
+/**
+ * GTK_STYLE_CLASS_BOTTOM:
+ *
+ * A CSS class to indicate an area at the bottom of a widget.
+ *
+ * This is used by widgets that can render an area in different
+ * positions, such as tabs in a #GtkNotebook.
+ */
+#define GTK_STYLE_CLASS_BOTTOM "bottom"
+
+/**
+ * GTK_STYLE_CLASS_LEFT:
+ *
+ * A CSS class to indicate an area at the left of a widget.
+ *
+ * This is used by widgets that can render an area in different
+ * positions, such as tabs in a #GtkNotebook.
+ */
+#define GTK_STYLE_CLASS_LEFT "left"
+
+/**
+ * GTK_STYLE_CLASS_RIGHT:
+ *
+ * A CSS class to indicate an area at the right of a widget.
+ *
+ * This is used by widgets that can render an area in different
+ * positions, such as tabs in a #GtkNotebook.
+ */
+#define GTK_STYLE_CLASS_RIGHT "right"
 
 /* Predefined set of widget regions */