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The rule of Delboeuf

"The rule of Delboeuf" is a rule that the appearance of a circle of the same size changes if the size of the surrounding frame is different.

In the layout on the Web, even if the characters are arranged in the same size, they may look different in size due to the influence of the surrounding frame.

The rule of Delboeuf

Optical illusion of excessive upward distance

The "illusion of excessive upward distance" means that figures of the same size should be lined up, but the one slightly above looks larger.

The button to the next page on this screen is also shifted up so that the reader does not feel uncomfortable.


Hermann grid

"Hermann grid" is a figure in which a gray circle can be seen in the white space between the checkered patterns. At first glance, it looks fashionable, but if you use such a pattern in the dark, the reader's eyes will get tired, so be careful.