Have you ever built a web page before? I’m not sure if you can write such a game with no experience, but anyway - the developer tools will be your best friend when you start building your own pages, so it’s a good idea to get familiar with it as soon as possible.
In your screenshot, the left side shows the structure of the HTML, and to the right, you see the CSS styles. The currently selected element is the
<body>, so the CSS window shows you the styles for the
Click on the arrow in the upper left (left of the word “Inspector”), then click on one of the words on the page. The HTML window will select the
<span> that wraps the word now, and the CSS window will show the styles that are applied.
Here’s a screenshot from Chrome’s developer tools (they’re almost exactly the same in Firefox):
You see the
<div id="word-section">, it contains a
<span> for each word. Some have a class of
current-word and so on. In the CSS window, you see that everything with a class of
.correct-word-c has a color set to some light green.