Use 'my_custom_class" for the programmaticaly set style (#214)

The "my_custom_class" style was unused, but was meant to style the last label

Author: UrtsiSantsi

src/Styling with CSS/code.rs

@@ -3,5 +3,5 @@ use gtk::prelude::*;
 
 pub fn main() {
     let basic_label: gtk::Label = workbench::builder().object("basic_label").unwrap();
-    basic_label.add_css_class("css_text");
+    basic_label.add_css_class("my_custom_class");
 }

src/Styling with CSS/main.js

@@ -1,3 +1,3 @@
 const basic_label = workbench.builder.get_object("basic_label");
 
-basic_label.add_css_class("css_text");
+basic_label.add_css_class("my_custom_class");

src/Styling with CSS/main.py

@@ -6,4 +6,4 @@
 
 basic_label: Gtk.Label = workbench.builder.get_object("basic_label")
 
-basic_label.add_css_class("css_text")
+basic_label.add_css_class("my_custom_class")

src/Styling with CSS/main.vala

@@ -2,5 +2,5 @@
 
 public void main () {
     var basic_label = (Gtk.Label) workbench.builder.get_object ("basic_label");
-    basic_label.add_css_class ("css_text");
+    basic_label.add_css_class ("my_custom_class");
 }