What is the problem with div getting the screen width in the vue-cli project?

clipboard.png

clipboard.png

clipboard.png
problems such as the picture above, the widths of the first two boxes are normal, but the width of the third box (many boxes are not the right width) becomes much larger. The result under Google browser feels very strange. Does any boss know what"s going on?

Mar.13,2021

found the reason, I cheated myself. I set the root element too small, Google does not support less than 12, sometimes 7.5 he defaults to 12, so it becomes very big

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