The `box-shadow` property attaches one or more shadows around the frame of an element (can be inside). It's an option that gives you the power to easily design wonderful shadow effects. Box shadows are a great way to elevate the visuals of your web page.
These are two `length` values to set the shadow offset. <offset-x> specifies the horizontal distance. Negative values place the shadow to the left of the element. `offset-y` specifies the vertical distance. Negative values place the shadow above the element. See `length` for possible units.
* #### blur-radius (default: 0)
This is a third `length` value. The larger this value, the bigger the blur, so the shadow becomes bigger and lighter. Negative values are not allowed. If not specified, it will be 0 (the shadow's edge is sharp).
This is a fourth <length> value. Positive values will cause the shadow to expand and grow bigger, negative values will cause the shadow to shrink. If not specified, it will be 0 (the shadow will be the same size as the element).
To maximize compatibility, it is recommended that you declare box shadow properties for `moz-appearance` and `webkit`, this extends the normal syntax to:
However, this step can be ignored if it is creating confusion, as moz property and webkit property will only work in specific applications such as Firefox, and are not on a standards track.