Let's talk a little bit about block level elements. The heading 1 (h1), heading 2 (h2), paragraphs (p), list items (li), and divs (div) are all examples of natural block level elements. Block level elements have two defining traits: they expand the full width available, and they force elements that come after them to appear on the next line, meaning they stack on top of each other. So let's remove the box-sizing property from our declaration block as well as the width property to demonstrate how they take up the full width available if no width is specified:
h1 {
font-size: 40px;
line-height:1.4;
font-weight: bold;
color: #0072ae background-color: black; padding: 50px; margin: 50px; border: ...
