Last but not least, there are four interesting icons sitting in the bottom-left corner of the Customizer window, as demonstrated in the following screenshot:
From the left, they are the Hide Controls button (this hides the whole Customizer sidebar to give you a bigger canvas when adjusting your website), the desktop view icon, the tablet view icon, and the mobile view icon. Those final three icons are particularly important. These days, more people tend to browse the web on their mobile devices than on classic desktop computers. Because of that, it's crucially important for you to make sure that your website displays properly on those devices. These three icons—the desktop view icon, the tablet view icon, and the mobile view icon, allow you to do just that. When you click on any of them, the whole Customizer window will change in size to emulate the display mode on tablets and mobile devices. Switching back and forth between the modes, you can make sure that your site looks great on all devices. We will expand on the topic of mobile optimization in the very next part of this chapter.