Add full-stack questions

src/data/question-groups/full-stack/content/responsive-design.md

@@ -3,8 +3,11 @@
 To help ensure this, you can use flexible grids (either `CSS Grid` or `Flexbox`).
 
 You will also have to apply media queries which help set breakpoints where the different styles need to be applied based on the width of the window:  
-`@media (max-width: 768px) {`  
-  `.container { flex-direction: column; }`  
-`}`
+
+```css
+@media (max-width: 768px) {
+  .container { flex-direction: column; }
+}
+```
 
 You can also use relative units (`%`, `em`, `rem`) instead of fixed units (`px`) to ensure the values automatically adapt to the size of the container.