Problema con Firefox 57 (Quantum) -- Problem with Firefox 57 (Quantum)

Hi. A few days ago I’m having problems with Firefox 57, the letters disappear in certain pages, I reinstalled it and nothing happens. The characters are but can not be seen. I was installing Windows XP, 7 and new Google fonts. An image watch more than a thousand words.

Hola. Hace pocos días estoy teniendo problemas con Firefox 57, desaparecen las letras en ciertas paginas, ya lo reinstale y no pasa nada. Los caracteres estan pero no se ven. Estuve instalando fuentes de Windows XP, 7 y nuevas de Google. Una imagen vele mas que mil palabras.

This page with dark theme

Greetings and thanks in advance
Saludos y gracias por adelantado

Ask Ubuntu, where you already posted this question, is a proper place to ask for support. This site, however, is not intended for user support.

I’ve moved this to the https://community.ubuntu.com/c/support-help-requests category because this site isn’t designed to take tech support questions. Sorry. I’d recommend using one of the official support channels listed on the https://community.ubuntu.com/t/finding-help/712 page.