Change css to uppecase

docs/10.1-animation.md

@@ -216,7 +216,7 @@ Every DOM component that React can render is available for use. However, `compon
 >
 > Prior to v0.12, when using DOM components, the `component` prop needed to be a reference to `React.DOM.*`. Since the component is simply passed to `React.createElement`, it must now be a string. Composite components must pass the factory.
 
-Any additional, user-defined, properties will become properties of the rendered component. For example, here's how you would render a `<ul>` with css class:
+Any additional, user-defined, properties will become properties of the rendered component. For example, here's how you would render a `<ul>` with CSS class:
 
 ```javascript{1}
 <ReactTransitionGroup component="ul" className="animated-list">