Practices for using em in CSS

Let's look at the full HTML code of the page:

<html>
	<head>
		<title></title>
	</head>
	<body>
		<main>
			<div>
				<p>
					text
				</p>
			</div>
		</main>
	</body>
<html>

By default, all page tags have some font size. In fact, the html tag has some font size by default:

html {
	font-size: 16px; /* default value */
}

So we can give page tags sizes in em, and they will calculate their sizes relative to their immediate parents.

Let's, for example, specify the font size for the tag main:

main {
	font-size: 1.5em; /* corresponds to 24px */
}

Now let’s specify the font size for the tag div:

div {
	font-size: 2em; /* corresponds to 48px */
}

Let's say we have HTML code for which we will solve problems:

<main>
	<h1>header</h1>
	<div>
		<p>
			text
		</p>
		<p>
			text
		</p>
	</div>
	<div>
		<p>
			text
		</p>
		<p>
			text
		</p>
	</div>
</main>

In all the problems below, rewrite all units specified in pixels into em:

main {
	margin: 16px auto;
}

h1 {
	font-size: 32px;
}
p {
	font-size: 32px;
}

main {
	margin: 32px auto;
}

h1 {
	font-size: 32px;
}
div {
	font-size: 16px;
	margin-bottom: 32px;
}
p {
	font-size: 20px;
}