Most "Light" font faces are not separate fonts; they are part of a font family that is packaged together under a single name. So, for example, Avenir Light is part of Avenir. Some programs may show Avenir Light as a separately selectable font, but this is not the case for web browsers.
To use a Light font in CustomReader, enter the font family name (such as "Avenir") in the body font field, and then specify a font weight in the stylesheet under the Advanced tab. Look for the rule that starts with ".page". In the default stylesheet, it looks like this:
.page {
font-family: "Georgia";
color: #414141;
}
Add a "font-weight" declaration to this block. A value of 300 or lower will cause Safari to use the Light variation, if it exists.
.page {
font-family: "Avenir";
font-weight: 300;
color: #414141;
}
You can hold down the Option key to preview the effect of your change on Reader. When you're done, click Save.
Please note: The difference between Avenir and Avenir Light is quite subtle. To see a bigger difference, try Avenir Next and Avenir Next Light.
Chul