You can try implementing your OTF font using @font-face like this:
@font-face {
font-family: GraublauWeb;
src: url("path/GraublauWeb.otf") format("opentype");
}
@font-face {
font-family: GraublauWeb;
font-weight: bold;
src: url("path/GraublauWebBold.otf") format("opentype");
}
But, if you want to support a wide variety of modern browsers then you can switch to WOFF and TTF font types. WOFF type can be implemented by every major desktop browser, while the TTF type is a fallback for older Safari, Android and iOS browsers.
If your font is a free font, then you can convert your font using, for example, a onlinefontconverter.
@font-face {
font-family: GraublauWeb;
src: url("path/GraublauWebBold.woff") format("woff"), url("path/GraublauWebBold.ttf") format("truetype");
}
But, if you want to support every browser that is still out there (not necessary anymore IMHO), then you can add some more font-types like:
@font-face {
font-family: GraublauWeb;
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 */
}
To get a detailed view of which file-types are supported by which browsers, you can refer to these docs:
@font-face Browser Support
EOT Browser Support
WOFF Browser Support
TTF Browser Support
SVG-Fonts Browser Support