Where does the indentation come from when the screen is reduced?

Question

Design

Hello. Here is the site In chrome, at a resolution of 768, such an indent appears clip2net.com/s/3KK0UX6 in Mozilla it is not. Please tell me what could be the reason.

Answer 1

All photo stocks are filled with this effect: https://ru.depositphotos.com/18702551/stock-illust...
I doubt that there is a panacea, how to make this effect in a couple of clicks. At one time I did it with the help of a vector, but now I use ready-made textures. The fact is that the uniqueness of such textures will not be noticeable, so you can use something ready for the tag " Abstract geometric white background "
Well, or like this - there is more choice
. Then, accordingly, change the color to the desired one.

Answer 2

Polygon, polygonal. There is no point in doing it yourself, there are a lot of them ready-made. If done, then with a pen, a figure, pens.

Answer 3

* {
  outline: 1px solid red;
}