Cascading Style Sheets (CSS) are used to separate the style of a web page (fonts, colors, spacing, positioning, etc.) from its content. When using CSS, a CSS file defines the style for various HTML elements such as hypertext links. CSS files also define "classes" which define style information for arbitrary HTML elements. In this case, elements in the HTML declare the name of their CSS class to have that particular style applied to them. CSS class names should refer to what the HTML element is (e.g. Order Summary) rather than suggest the style that should be applied to it.

In Elastic Path, CSS files are stored within each individual theme directory, in template-resources/stylesheet.