First reset 1em to 10px for the whole page.
body {
font-size: 62.5%; /* Resets 1em to 10px */
}
Finally, set the font size for a section, such as the content.
#content {
font-size: 1.6em;
line-height: 1.6em;
}
1.6em is equal to 16px.
The line-height is the distance between lines.
