The number of browsers and devices that are used to surf the Web is much larger than just a few years ago. All these devices have different properties. Large or small screens, high or low resolution, different bandwidth at different locations and so on.
To view a website in the best possible way, no matter the device, a design that automatically adjusts depending on the characteristics of the device that loads it, can be used. This type of Web design (responsive Web design) is usually carried out by making everything fluid/elastic, and with the help of CSS3 media queries.