You are missing the colon after ".MathJax"
. Your code should be
<script type="text/x-mathjax-config">
MathJax.Hub.Config({
jax: ["input/TeX", "output/HTML-CSS"],
tex2jax: {
inlineMath: [ ['$', '$'] ],
displayMath: [ ['$$', '$$']],
processEscapes: true,
skipTags: ['script', 'noscript', 'style', 'textarea', 'pre', 'code']
},
messageStyle: "none",
"HTML-CSS": {
preferredFont: "TeX",
availableFonts: ["STIX","TeX"],
styles: {".MathJax": {color: "#CCCCCC"}}
}
});
</script>
and then it should work for you.