• The smaller containing block that results when an absolutely-positioned element is given non-auto inset values (e.g., top, right, bottom, left, or the inset shorthand). These inset values shrink the element’s original containing block, creating a new reference box used for sizing and positioning, as with CSS Anchor Positioning features such as position-area and position-try-order.

1. Related terms: Containing block · Block-level element · Anchor positioning · Block box
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