@page rule A CSS rule that defines the properties of the page box containing the content to be printed.

box-shadow property A CSS property that adds a drop shadow to any page element.

color gradient A visual effect in which one color gradually blends into another or, if transparent colors are used, fades away altogether.

CSS pixel The fundamental unit in CSS measurements.

device pixel The actual physical pixel rendered on a computer screen.

device-pixel ratio The number of device pixels matched to a single CSS pixel.

emulator A software program that runs on a desktop computer and emulates the actions of a different hardware device.

layout viewport A mobile device viewport that displays, virtually, the entire content of the Web page.

linear gradient A color gradient in which the color blending occurs in a straight line across an object's background.

linear-gradient() function A CSS function that creates a background color consisting of two or more colors blending into one another.

media attribute An attribute that specifies the device(s) associated with a style sheet.

media group A CSS category that describes how different media devices render content; the four media groups are continuous or paged; visual, audio, or tactile; grid or bitmap; and interactive or static.

media query An HTML5 and CSS3 statement that specifies the media device for a style sheet as well as the properties of that device.

orphan The beginning lines of a page element when they appear at the bottom of a printed page.

page box A CSS model of printed page content; the content of a document is contained within the page area and surrounded by the margin area, which contains the space between the printed content and the page edges.

page name A named style for printed pages other than the first, left, or right pages.

page-break-after property,

page-break-avoid property A CSS property that defines whether or not to avoid inserting a page break within the selected object.

page-break-before property A CSS property that defines whether or not to manually insert a page break before the selected object.

radial gradient A gradient in which color blending starts from a single point within an object and proceeds outward in a circular or elliptical shape.

rotate() function A CSS transformation function that rotates a page object by a specified angle.

SDK. See Software Development Kit

simulator A simpler version of an emulator, which simulates some of the behavior of a device but does not emulate the operations of the hardware.

size property A property that, when used with the @page rule, defines the size and orientation of the printed page.

software development kit (SDK) A set of development tools that can be used to create applications for software programs, devices, or hardware platforms.

text-shadow property A CSS property that adds a drop shadow to a text string.

transform property A CSS property that applies a 2D or 3D transformation to a page object.

viewport meta tag A meta tag that sets the size of the viewport on a mobile device.

viewport The window in which the contents of a Web page are displayed.

visual viewport The Web content that appears on the screen of a mobile device.

widow The ending lines of a page element that appear at the top of a printed page.