html, body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  text-align: center;
}

/** 
  Our buttons '#open-modal, #close-modal' 

  1) For the background colour use 'royalblue'
  2) Be aware of the colour, padding & font size
  3) Make sure the cursor has a pointer so that it demonstrates to the user the button is clickable
**/
#open-modal, #close-modal {
  background-color: royalblue;
  color: white;
  padding: 15px;
  font-size: 20px;
  cursor: pointer;
}

/** 
  Modal: #modal

  1) Add a temporary background colour of 'orange'
  2) Add a padding of 20px
  3) Add a height of 200px
  4) Add a margin of 0 & auto to make sure our Modal is centered
**/