CSS Background and Borders is a module of CSS that defines how background and borders of elements are described. Borders can be lines or images, boxes can have one or multiple backgrounds, have rounded corners, and shadows.
CSS Lists and Counters is a module of CSS that defines how lists are laid out, how the list marker can be styled and how authors can create new counters.
CSS counters are, in essence, variables maintained by CSS whose values may be incremented by CSS rules to track how many times they're used. This lets you adjust the appearance of content based on its placement in the document. CSS counters are an implementation of Automatic counters and numbering in CSS 2.1.
The element()CSS function defines an <image> value generated from an arbitrary HTML element. This image is live, meaning that if the HTML element is changed, the CSS properties using the resulting value are automatically updated.
The flex-basisCSS property specifies the flex basis which is the initial main size of a flex item. This property determines the size of the content-box unless specified otherwise using box-sizing.
The flex-growCSS property specifies the flex grow factor of a flex item. It specifies what amount of space inside the flex container the item should take up.
Thefont-style CSS property lets you select italic or oblique faces within a font-family. Italic forms are generally cursive in nature, usually using less horizontal space than their unstyled counterparts, while oblique faces are usually just sloped versions of the regular face. Both italic and oblique faces are simulated by artificially sloping the glyphs of the regular face (see font-synthesis for control over this).
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 <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 image-renderingCSS property provides a hint to the browser about the algorithm it should use to scale images. It applies to the element itself as well as any images supplied in other properties for the element. It has no effect on non-scaled images.
The CSS linear-gradient() function creates an <image> which represents a linear gradient of colors. The result of this function is an object of the CSS <gradient> data type. Like any other gradient, a CSS linear gradient is not a CSS <color> but an image with no intrinsic dimensions; that is, it has neither natural or preferred size, nor ratio. Its concrete size will match the size of the element it applies to.