CSS: “perspective”: “0” is not valid, only values greater than “0” allowed.

The CSS perspective property does not accept 0 as a valid value. It must be either none or a positive length greater than zero.

The perspective property defines the distance between the viewer and the z=0 plane, which determines the intensity of 3D effects on child elements. A value of 0 is mathematically undefined (it would place the viewer directly on the plane), so the specification rejects it. If the goal is to remove perspective entirely, use none. If the goal is a very strong perspective effect, use a small positive value like 1px.

The property applies to the element's children, not the element itself. A smaller value creates a more dramatic 3D effect, while a larger value creates a subtler one.

Invalid example

<div style="perspective: 0;">
  <div style="transform: rotateY(45deg);">Content</div>
</div>

Valid examples

To disable perspective:

<div style="perspective: none;">
  <div style="transform: rotateY(45deg);">Content</div>
</div>

To apply a strong (but valid) perspective:

<div style="perspective: 1px;">
  <div style="transform: rotateY(45deg);">Content</div>
</div>

Learn more:

MDN Reference

CSS perspective - MDN Web Docs

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W3C Reference

CSS Transforms Module Level 2

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