I use Firefox's Reader View to fix low contrast text. You need to edit userContent.css to get the full contrast:

    @-moz-document url-prefix("about:reader") {
    body {
      background-color: #FFFFFF !important;
      color: #000000 !important;
      }
    }

If Reader View doesn't work, it's usually easy to find the font color CSS in the Web Developer tools.