osu/osu.Game/Graphics/UserInterface/OsuButton.cs

using System;
using OpenTK.Graphics;
using osu.Framework.Graphics.UserInterface;

namespace osu.Game.Graphics.UserInterface
{
    public class OsuButton : Button
    {
        public OsuButton()
        {
            Height = 25;
            Colour = new Color4(14, 132, 165, 255);
        }
    }
}