[viviena]

I don't know what might help. I currently designate line-height like this without any problems:

html { 
	font-family: "Vollkorn" !important;
}

body { 
	font-family: "Vollkorn" !important;
	line-height: 1.05em;
}

.mainBody {
	font-family: "Vollkorn" !important;
}

.calibre {
	font-family: "Vollkorn" !important;
}

p {
	font-family: "Vollkorn" !important;
}

@font-face {
  font-family: "Vollkorn";
  font-weight: normal;
  font-style: normal;
  src: url(res:///Data/fonts/vollkorn/Vollkorn-Regular.ttf);
}

@font-face {
  font-family: "Vollkorn";
  font-weight: bold;
  font-style: normal;
  src: url(res:///Data/fonts/vollkorn/Vollkorn-Bold.ttf);
}

@font-face {
  font-family: "Vollkorn";
  font-weight: normal;
  font-style: italic;
  src: url(res:///Data/fonts/vollkorn/Vollkorn-Italic.ttf);
}

@font-face {
  font-family: "Vollkorn";
  font-weight: bold;
  font-style: italic;
  src: url(res:///Data/fonts/vollkorn/Vollkorn-BoldItalic.ttf);
}

(To make sure I wasn't imagining the extra line-height, I even took another screenshot after my line-height adjustment and measured the difference with a ruler. I'm good at fooling myself otherwise.)

The only difference I can see is that you have no semi-colon after the second CSS property, but that shouldn't usually matter, I think? It doesn't for most web design, not when it's the final property in a ruleset.