Qazqa JOHANNA User manual

Hello, I'm your chat assistant. I have reviewed the instruction manual for the QAZQA Johanna CL series of lights. This document provides guidance on the safe installation, suitable light sources, and maintenance. It specifies the use of E27 halogen bulbs up to 40W and advises on waiting for the bulb to cool before replacing. I'm ready to assist with your questions regarding this product.
What type of light source is suitable for this fixture?

What should I do before replacing a halogen lamp?

What is the diameter of the Johanna CL 30 lights?