[Doitsu]

Calibre supports stylistic sets, which you can use to select alternate glyphs.

Spoiler:

@font-face {
  font-family: 'Cormorant';
  font-weight: normal;
  font-style: normal;
  src: url(../Fonts/Cormorant-Regular.ttf);
}

body {
  font-family: 'Cormorant';
}

.ss10 {
  -moz-font-feature-settings: "ss10";
  -webkit-font-feature-settings: "ss10";
  font-feature-settings: "ss10";
}

You might find the OpenType Tester website useful for experimenting with OpenType features.