Merge pull request #887 from maxrchung/patch-3

replace with question mark in css-questions

src/questions/css-questions.md

@@ -38,6 +38,6 @@ permalink: /questions/css-questions/index.html
 * How is clearfix css property useful?
 * Can you explain the difference between px, em and rem as they relate to font sizing?
 * Can you give an example of a pseudo class? Can you provide an example use case for a pseudo class? 
-* What is the difference between a block level element and an inline element. Can you provide examples of each type of element?
+* What is the difference between a block level element and an inline element? Can you provide examples of each type of element?
 * What is the difference between CSS Grid and Flexbox? When would you use one over the other?
 * What is the difference between fixed, fluid and responsive layouts?