Advanced - Create link box
Example analysis:
Use display:block; to convert the a element into a block element, and then set the width and height of the a element.
Use the font-weight property to set the font weight.
Use the color and background-color properties to set the font color and background color.
Use text-align:center; to center the text within the a element horizontally.
Use text-decoration; to remove the underline of the link.
