This afternoon, I found that when I preview the print layout of the
posts in Chrome, some Mathjax block equations enclosed with
\begin{equation}
weren’t displayed properly. I think it should be
due to my settings in sass/custom/_print.scss
because the contents
in Mathjax’s official demo can be rendered properly in the print
preview.^{1} Therefore, I deleted some obsolete lines of code in that
SCSS file .^{2} Actually, since it takes time for loading MathJax, if
I open the print preview before the block equations are ready, then I
will see the source code of those equations.

Refer to A Test of Equation Numbering in MathJax Example Pages for details. ↩