How to include a font .ttf using CSS?

Did you try format?

@font-face {
  font-family: 'The name of the Font Family Here';
  src: URL('font.ttf') format('truetype');
}

Read this article: http://css-tricks.com/snippets/css/using-font-face/

Also, might depend on browser as well.

Only providing .ttf file for webfont won't be good enough for cross-browser support. The best possible combination at present is using the combination as :

@font-face {
    font-family: 'MyWebFont';
    src: url('webfont.eot'); /* IE9 Compat Modes */
    src: url('webfont.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
         url('webfont.woff') format('woff'), /* Modern Browsers */
         url('webfont.ttf')  format('truetype'), /* Safari, Android, iOS */
         url('webfont.svg#svgFontName') format('svg'); /* Legacy iOS */
}

This code assumes you have .eot , .woff , .ttf and svg format for you webfont. To automate all this process , you can use : Transfonter.org.

Also , modern browsers are shifting towards .woff font , so you can probably do this too :

@font-face {
    font-family: 'MyWebFont';
    src: url('myfont.woff') format('woff'), /* Chrome 6+, Firefox 3.6+, IE 9+, Safari 5.1+ */
         url('myfont.ttf') format('truetype'); /* Chrome 4+, Firefox 3.5, Opera 10+, Safari 3—5 */
}  

Read more here : http://css-tricks.com/snippets/css/using-font-face/

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Look for browser support : Can I Use fontface