When elements are positioned to overlap (i.e. using `position: absolute | relative | fixed | sticky`), the element coming later in the HTML markup will, by default, appear on the top of the other elements. However, the `z-index` property can specify the order of how elements are stacked on top of one another. It must be an integer (i.e. a whole number and not a decimal), and higher values for the `z-index` property of an element move it higher in the stack than those with lower values.
Add a `z-index` property to the element with the class name of `first` (the red rectangle) and set it to a value of 2 so it covers the other element (blue rectangle).