You are serving Menlo font on your website (monospace). This is not an open font. It is Apple IP and is not licensed for being served over the internet.

Although it is a derivative of the FOSS fonts-- Bitstream Vera and DejaVu, Menlo itself is not released with an open license. It's only meant for use with Apple devices.

I'd suggest changing to one of the many high quality FOSS fonts available online.