Let's add a new feature to our application to allow the user to select a color scheme, or theme, so they can customize the look and feel of the application. We can change the look of a web page by dynamically loading CSS files to override existing styles in our default stylesheet. To implement this, we will add a drop-down list of themes to our application that the user can choose from. When they change the theme, it will change the stylesheet which will change the color of the page.