The basic idea was to find the best way to display only one question on the screen, adequate for the current phase of the form filling process. At the same time, the filling should resemble a normal conversation between two people. To achieve this concept in practice, the developers had to completely “clean up” the form interface, getting rid of the slightest clutter - it was necessary to remove everything that could distract the user's attention from the question he is currently answering. However, it was necessary for the user to have a general idea of the form, so that he can easily navigate it and know the number of remaining questions.
The solution wasn't found right away. For example, in one of the oman phone number data early versions, the question that appeared "closed" as soon as you answered it. The problem of "showing one question at a time" was solved, that's true, but because the animation speed was too high, it was difficult to navigate the entire form.
After many tests, a simple but effective solution was found: the "highlighted" active (current) question was placed in the center of the monitor, the previous and next ones were visible, although they were less noticeable because they were displayed in a less bright font and contrasted less with the background.
By placing the active question field in the center of the display, the developers "untied their hands": now they could use large fonts - 24 pixels for the UI displayed on the desktop, 16 and 24 pixels for mobile interfaces for different types of devices. Very few fonts look good at a size smaller than 16 pixels, so having solved one issue (the overall composition), marketers and designers simultaneously solved another, no less important issue - they improved the UI design by increasing the readability of text content.
In turn, the change in the user interface naturally affected the user experience being developed: typography using large fonts forced marketers to shorten the questions so that each word takes up less space in the line to fill in. It is necessary to optimize the question so that it is precise and concise: then all the letters will fit in the form field, and the respondent will be more likely to want to answer it.