[css] Override element.style using CSS

Of course the !important trick is decisive here, but targeting more specifically may help not only to have your override actually applied (weight criteria can rule over !important) but also to avoid overriding unintended elements.

With the developer tools of your browser, identify the exact value of the offending style attribute; e.g.:

"font-family: arial, helvetica, sans-serif;"

or

"display: block;"

Then, decide which branch of selectors you will override; you can broaden or narrow your choice to fit your needs, e.g.:

p span

or

section.article-into.clearfix p span

Finally, in your custom.css, use the [attribute^=value] selector and the !important declaration:

p span[style^="font-family: arial"] {
  font-family: "Times New Roman", Times, serif !important;
}

Note you don't have to quote the whole style attribute value, just enough to unambigously match the string.