GridItem

GridItem refers to an individual element within a CSS Grid Layout. CSS Grid Layout is a two-dimensional layout system for the web, allowing for the arrangement of elements in rows and columns. A GridItem is one of the direct children of a grid container. These items are automatically placed into the grid cells by default.

Developers can explicitly control the positioning and spanning of a GridItem within the grid using properties like grid-column and grid-row. The grid-column property allows a GridItem to span across multiple columns, while grid-row allows it to span across multiple rows. These properties can accept values such as line numbers, line names, or keywords like 'span' followed by a number.

For example, `grid-column: 1 / 3;` would make a GridItem start at the first column line and end at the third column line, effectively spanning two columns. Similarly, `grid-row: span 2;` would make the item occupy two rows.

GridItems can also be influenced by alignment properties applied to the grid container, such as justify-items and align-items, which control how items are aligned within their grid areas. Individual GridItems can also have their alignment overridden using justify-self and align-self. Understanding how to manipulate GridItems is fundamental to creating complex and responsive grid-based layouts.