rotation-point property is used to define a "rotation point" when rotating an element using the
Important Note: The
rotation properties were proposed in the CSS Basic Box Model Level 3, which is now outdated.
To perform rotations in CSS, use the
transform property instead (and its associated properties). Although this property is still in working draft status (at the time of writing), it appears to be the way forward when dealing with rotating HTML elements with CSS.
As per the W3C draft specification, here are the allowed values.
This property accepts a pair of values that defines a point as an offset from the top left border edge. Percentages refer to the width and height of the border box. Values may be negative.
If only one percentage or length value is given, it sets the horizontal position only, and the vertical position will be 50%. If two values are given, the horizontal position comes first. Combinations of keyword, length and percentage values are allowed, (e.g.,
|Applies to:||This property applies only to block-level elements|
|Computed Value:||For the <length> the absolute value, otherwise a percentage.|
At the time of writing, CSS3 was still under development and browser support for many CSS3 properties was limited or non-existent. For maximum browser compatibility many web developers add browser-specific properties by using extensions such as
-webkit- for Safari and Google Chrome,
-ms- for Internet Explorer,
-moz- for Firefox,
-o- for Opera etc. As with any CSS property, if a browser doesn't support a proprietary extension, it will simply ignore it.
This practice is not recommended by the W3C, however in many cases, the only way you can test a property is to include the CSS extension that is compatible with your browser.
Be aware that if you choose to use the proprietary CSS extensions in a live environment, your code will not pass any W3C CSS validation, as the browser-specific properties are not valid W3C properties.
Many of the CSS3 examples on this website include these browser specific properties. If they weren't included, most of the examples wouldn't work for most users (at least, not until possibly years after the article was written).
The major browser manufacturers are working to support the W3C properties, and eventually, you will be able to omit these browser-specific properties.