I want a flat, low bitrate, low color, easily re-identifiable icon that, when 'clicked', depresses in a perfect square footprint to indicate that I have done an

I want a flat, low bitrate, low color, easily re-identifiable icon that, when 'clicked', depresses in a perfect square footprint to indicate that I have done an action. What is shown here is the exact opposite of what I want in a GUI.