marginleftright

Marginleftright is not an official CSS property. In practical terms, it is sometimes used as an informal shorthand to refer to the horizontal margins of an element—the space on its left and right sides. In standard CSS, horizontal margins are controlled by the properties margin-left and margin-right, or by the single shorthand margin that can set multiple sides at once.

Using the left and right margins individually allows precise control over horizontal spacing. For example, margin-left: 1rem; margin-right: 1rem; sets equal horizontal margins, while margin: 0 auto; centers a block-level element with a fixed width by applying automatic margins on the left and right. The latter pattern is common for centering content within a page.

Horizontal margins play a key role in page layout and responsiveness. They influence alignment, create gutters in grid systems, and help maintain proportional spacing when screen sizes change. Relative units such as ems, rems, or percentages can be used to scale margins with typography or container width. CSS features like max-width and responsive media queries further refine how horizontal margins behave across devices.

Nonstandard usage: some documentation, style guides, or CSS preprocessors may introduce a composite concept or a custom property named marginleftright for convenience. However, this does not reflect a standard CSS feature, and developers should rely on margin-left, margin-right, or the margin shorthand for cross‑browser compatibility.

See also: margin, margin-left, margin-right, responsive design, CSS shorthand properties.