sleepy-launcher/assets/ui/first_run/welcome.blp

using Gtk 4.0;
using Adw 1;

Gtk.Box page {
    orientation: vertical;
    hexpand: true;

    Adw.PreferencesPage {
        Adw.PreferencesGroup {
            Gtk.Image {
                resource: "/org/app/assets/images/icon.png";

                vexpand: true;
                margin-top: 16;
            }

            Gtk.Label {
                label: "An Anime Game Launcher";
                margin-top: 32;

                styles ["title-1"]
            }

            Gtk.Label {
                label: "Hi there! Welcome to the An Anime Game Launcher. We need to prepare some stuff and download default components before you could run the game";

                wrap: true;
                justify: center;
                margin-top: 32;
            }
        }

        Adw.PreferencesGroup {
            vexpand: true;
            valign: center;

            Gtk.Box {
                orientation: horizontal;
                spacing: 8;
                halign: center;

                Gtk.Button continue_button {
                    label: "Continue";

                    styles ["suggested-action"]
                }

                Gtk.Button advanced_button {
                    label: "Advanced";
                    tooltip-text: "You can choose default folders paths";
                }
            }
        }
    }
}