@csstools/postcss-ic-unit is a PostCSS plugin that provides support for the ic and cap CSS units, ensuring compatibility across different browsers. These units, representing the advance measure of an "水" (ideographic character) glyph and the advance measure of a capital letter, respectively, prove useful particularly in East Asian typography. The plugin transforms these units to pixel values, enabling consistent layout and rendering even where native support is lacking. This ensures your CSS remains robust and visually consistent.