startmargin

Start margin is a layout concept in typography and digital design that refers to the outer margin at the start edge of a block of content. The start edge is determined by the writing direction of the document: in left-to-right languages, the start margin lies on the left; in right-to-left languages, it lies on the right. This distinction helps ensure consistent alignment and spacing across languages and layouts.

In typesetting and document design, the start margin can influence the visual rhythm and indentation of blocks, affecting how text lines up with margins, columns, and other elements. It complements the end margin, which sits at the opposite, or trailing, edge. Together they help maintain proportional whitespace and readability in multi-column or multi-block layouts.

In modern web development, the start margin is commonly implemented using CSS logical properties rather than fixed physical margins. The property margin-inline-start corresponds to the start margin, automatically adapting to writing mode. Its counterpart, margin-inline-end, represents the end margin. These properties map to physical margins (margin-left or margin-right) depending on directionality, so a design remains consistent for both LTR and RTL languages. Older practices used margin-left or margin-right, which do not adapt to writing direction.

Practical use cases include ensuring consistent indentation, aligning blocks with page margins, and creating responsive layouts that honor internationalization. Start margin is part of broader CSS logical properties that support writing-mode aware design, improving accessibility and international compatibility. See CSS logical properties, writing mode, and page layout concepts for related topics.