For each design you want to make a layout responsive for different devices. There are two types of approaches how to start designing: either from the biggest screen to the lowest, or from the mobile first and then increase the size and make adaptive views as you go.
For the Casino project the design first was made for the desktop. Based on it, a mobile optimization was needed. I made prototype responsive using Axure. I created three adaptive views: Desktop (min-width: 1200px), Landscape Tablet (min-width: 1024px) and iPhone 8 Plus (min-width: 414px).
Here is the link for a project Responsive Demo.
Prototypes help to easily demonstrate how the design will behave. This is useful for design critics or for helping others to visualize how design will look and feel once the final product is built.
Rapid prototyping of mobile layouts can be done with Figma. It helps to produce useful UI design and workflows efficienly.