non breaking space preceding katex not workiing in HTML

Question

if I put a non breaking space before a katex inline formula like

<p>the quantity is represented by the variable&nbsp;$x$.</p>

It's good practice to avoid an orphan $x$. at the beginning of a line. However The non-breaking space  has no effect here. The problem also occurs with the final point of the sentence.

I am expecting variable $x$. to be unbreakable. It doesn't works in firefox or chrome.