Thanks to Anon, the solution is to check the Latin Extended in the Google font settings. The demo is updated.
CSS:
@font-face {
font-family: 'Signika';
font-style: normal;
font-weight: 700;
src: local('Signika-Bold'), url(http://themes.googleusercontent.com/static/fonts/signika/v3/F587cG5P5ff3TX6w4JlorxsxEYwM7FgeyaSgU71cLG0.woff) format('woff');
}
Or:
HTML:
<link rel="stylesheet" href="http://fonts.googleapis.com/css?family=Signika:700&subset=latin,latin-ext">