A <translation-value> or <length> can be a <number> without an unit identifier. In this case the number gets interpreted as "user unit". A user unit in the the initial coordinate system is equivalent to the parent environment’s notion of a pixel unit.

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Specifies a 3D rotation by the angle specified in last parameter about the [x,y,z] direction vector described by the first three parameters. A direction vector that cannot be normalized, such as [0,0,0], will cause the rotation to not be applied.

If the direction vector is not of unit length, it will be normalized. A direction vector that cannot be normalized, such as [0, 0, 0], will cause the rotation to not be applied. This function is equivalent to matrix3d(1 + (1-cos(angle))*(x*x-1), -z*sin(angle)+(1-cos(angle))*x*y, y*sin(angle)+(1-cos(angle))*x*z, 0, z*sin(angle)+(1-cos(angle))*x*y, 1 + (1-cos(angle))*(y*y-1), -x*sin(angle)+(1-cos(angle))*y*z, 0, -y*sin(angle)+(1-cos(angle))*x*z, x*sin(angle)+(1-cos(angle))*y*z, 1 + (1-cos(angle))*(z*z-1), 0, 0, 0, 0, 1).

]]> specifies a perspective projection matrix. This matrix scales points in X and Y based on their Z value, scaling points with positive Z values away from the origin, and those with negative Z values towards the origin. Points on the z=0 plane are unchanged. The parameter represents the distance of the z=0 plane from the viewer. Lower values give a more flattened pyramid and therefore a more pronounced perspective effect. For example, a value of 1000px gives a moderate amount of foreshortening and a value of 200px gives an extreme amount. The value for depth must be greater than zero, otherwise the function is invalid.

]]> Any computed value other than none for the transform results in the creation of both a stacking context and a containing block. The object acts as a containing block for fixed positioned descendants.

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The transform-origin CSS property lets you modify the origin for transformations of an element. For example, the transform-origin of the () function is the centre of rotation. (This property is applied by first translating the element by the negated value of the property, then applying the element's transform, then translating by the property value.)

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The transform-style CSS property determines if the children of the element are positioned in the 3D-space or are flattened in the plane of the element.

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The perspective CSS property determines the distance between the z=0 plane and the user in order to give to the 3D-positioned element some perspective. Each 3D element with z>0 becomes larger; each 3D-element with z<0 becomes smaller. The strength of the effect is determined by the value of this property.

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The values of the and perspective-origin properties are used to compute the perspective matrix, as described above.

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The CSS backface-visibility property determines whether or not the back face of the element is visible when facing the user. The back face of an element always is a transparent background, letting, when visible, a mirror image of the front face be displayed.

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