 The Light Dark function in CSS lets you easily adapt a color scheme to a user's preference for light or dark mode. Use the Light Dark function to specify two different color values within a single CSS property. The browser will automatically choose the appropriate color based on the element's computer color scheme value. For example, with the CSS on the screen, if the user selected a light theme, the element will have a line background. If the user selected a dark theme, the element will have a green background.