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CartoCSS is the syntax language that enables you to customize the style of your map data. Similar to working with a Cascading Style Sheet for styling webpages, CartoCSS is specific to the design of map symbolizer properties (such as marker size, marker color, line pattern, line stroke, text display, and so on). You can apply CartoCSS code directly from the STYLE tab of a selected map layer in CARTO Builder. Optionally, you can apply CartoCSS with CARTO.js and the Maps API.