Make task requirement consistent with the solution

It is a simple change,
I in the `Task 2` it is required that the border should have `1px`,
And the solution has `2px`, also the image provided look a lot more like a `2px`.

files/en-us/learn_web_development/core/styling_basics/basic_selectors/selectors_tasks/index.md

@@ -80,7 +80,7 @@ span {
 In this task, we want you to make the following changes to the look of the content in this example, without changing the HTML:
 
 - Give the element with an id of `special` a yellow background.
-- Give the element with a class of `alert` a 1px grey border.
+- Give the element with a class of `alert` a 2px grey border.
 - If the element with a class of `alert` also has a class of `stop`, make the background red.
 - If the element with a class of `alert` also has a class of `go`, make the background green.