diff --git a/src/libsysprof-gtk/sysprof-chart-layer.c b/src/libsysprof-gtk/sysprof-chart-layer.c
index 63acbee1..0f24b504 100644
--- a/src/libsysprof-gtk/sysprof-chart-layer.c
+++ b/src/libsysprof-gtk/sysprof-chart-layer.c
@@ -90,6 +90,7 @@ static void
 sysprof_chart_layer_class_init (SysprofChartLayerClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
   object_class->dispose = sysprof_chart_layer_dispose;
   object_class->get_property = sysprof_chart_layer_get_property;
@@ -101,6 +102,8 @@ sysprof_chart_layer_class_init (SysprofChartLayerClass *klass)
                          (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));
 
   g_object_class_install_properties (object_class, N_PROPS, properties);
+
+  gtk_widget_class_set_css_name (widget_class, "layer");
 }
 
 static void
diff --git a/src/libsysprof-gtk/sysprof-chart.c b/src/libsysprof-gtk/sysprof-chart.c
index 96a7b64c..0ed6bfdd 100644
--- a/src/libsysprof-gtk/sysprof-chart.c
+++ b/src/libsysprof-gtk/sysprof-chart.c
@@ -266,6 +266,8 @@ sysprof_chart_class_init (SysprofChartClass *klass)
                   2,
                   SYSPROF_TYPE_CHART_LAYER,
                   G_TYPE_OBJECT);
+
+  gtk_widget_class_set_css_name (widget_class, "chart");
 }
 
 static void