Web design is a design branch that deals with the process of creatively creating website aesthetics. The mentioned web interface is designed according to the colors of the product or service it provides. Most often the colors of the interface design itself come from the colors of a brand logo. Until recently, the interfaces were on light backgrounds, until 2019, a trend of dark mode appeared and brought out a dark theme. This option enables a functional and aesthetic change in web design which offers a completely new experience that has a different impact on users' perception. The background becomes dark and because of that – the colors and the brand product are brought to the center of attention. The first part of the master's thesis talks about web design itself and the characteristics of a good web design, as well as trends in 2021. The topic of the dark mode is also dealt with in more detail. The second part of the paper presents the developed modern user interface in light and dark mode, while the third part consists of a survey on the topic: "The impact of the dark mode web interface on users' perception."