 <p>In almost all cases, font glyphs are composed of <strong>filled shapes</strong>. They don't use the stroke (line). So when your SVGs are being converted to a font, the font SVGs are getting a fill applied, even if they didn't have one before.</p> <p>The differences between browsers is probably explained by the fact that each browser may be loading a different generated font type. Eg. woff vs TTF etc.</p> <p>The fix is to design your SVGs so that they only use filled shapes and <strong>don't</strong> rely on strokes (ie. line colour, width etc). If you follow the following rules, your glyphs should always work when converted:</p> <ol> <li>Keep your line colour as "none" or "transparent",</li> <li>Never use any fill colour except black (ie. don't use "white" to make holes)</li> <li>Never let shapes cross over themselves or other shapes.</li> </ol> <p>So, for example, in the case of your star, it should be designed as a filled star shaped object with a star shaped hole in it.</p>