How to make a square?

The issue is how to impose such a "Right angle" to paste as a picture does not fit!
8878cb138ac147c985061cd610d3b6df.jpg
Thanks in advance!
July 8th 19 at 11:17
3 answers
July 8th 19 at 11:19
Yes SPS) - juliana.Fe commented on July 8th 19 at 11:22
July 8th 19 at 11:21
codepen.io/aliencash/pen/qNrjJN

PS: I Wanted to ask where is the square... was in reality the author of "square" is a star. )
July 8th 19 at 11:23

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