The demo's #intro note was green. Here a different gallery notice carries the class alert and ID opening; use those selectors to see the same priority rule in action.
A note where the ID selector wins the cascade.
p { color: gray; }..alert { color: orange; }.#opening { color: green; } so the ID wins over the earlier two rules.Run the page. The note is green even though all three rules match it.
You have seen the cascade choose the more specific selector.
ID selectors outrank class selectors, which outrank element selectors.