You can specify properties that control how feature source layers appear on a map. For example, you can specify the scale ranges at which a layer is visible, set the line color, and add labels to the map features. You can also create a theme, which displays the data in varying styles to indicate different values in the data. To specify styles for a layer, you define a style for a scale range. By default, 0 - Infinity is the only scale range. Add narrower scale ranges as you define styles to define how the data should appear at various scales. For example, you could create one scale range that displays roads with thick lines when you zoom in, and create a second scale range that displays roads with thin lines when you zoom out.