The <angle>CSS data type represents angle values. Positive angles represent clockwise angles, negative angles represent counterclockwise angles. Its syntax is a <number> data type immediately followed by the unit (deg, grad, rad or turn). Like for any CSS dimension, there is no space between the unit literal and the number.
The <basic-shape> type can be specified using basic shape functions. When using this syntax to define shapes, the reference box is defined by each property that uses <basic-shape> values. The coordinate system for the shape has its origin on the top-left corner of the reference box with the x-axis running to the right and the y-axis running downwards. All the lengths expressed in percentages are resolved from the used dimensions of the reference box.
The <frequency>CSS data type denotes a frequency dimension, like the pitch of a speaking voice. It consists of a <number> immediately followed by the unit. Like for any CSS dimension, there is no space between the unit literal and the number.
The <gradient>CSS data type denotes a CSS <image> made of a progressive transition between two or more colors. A CSS gradient is not a CSS <color> but an image with no intrinsic dimensions; that is, it has no natural or preferred size, nor a preferred ratio. Its concrete size will match the one of the element it applies to.
The <image>CSS data type represents a 2D image. There are two kinds of images in CSS: plain static images, often referenced using a URL, and dynamically-generated images like gradients or representations of parts of the tree.
The <number>CSS data type represents a number, either integer or fractional. Its syntax extends the one of the <integer> data value. To represent a fractional value, add the fractional part — a '.' followed by one or several decimal digits — to any <integer> data value. Like for <integer> data type, there isn't any unit associated to a <number>, which is not a CSS dimension.
The <time>CSS data type denotes time dimensions expressed in seconds or milliseconds. They consists of a <number> immediately followed by the unit. Like for any CSS dimension, there is no space between the unit literal and the number.
The <timing-function>CSS data type denotes a mathematical function that describes how fast one-dimensional values change during transitions or animations. This in essence lets you establish an acceleration curve, so that the speed of the animation can vary over its duration. These functions are often called easing functions.