Display equations are not centerred in Jupyter notebooks

[newptcai]

If in a Jupyter/IJulia notebook, we write a code cell with the following lines

$$
1 + 2 = 3
$$
"""

then the output is a math equation rendered by MathJax.
However, the equation is not centred in the output cell.

However, the following code

$$
1 + 2 = 3
$$

in a markdown cell results in an equation proper centred in the cell after it is rendered by Mathjax.

I am not sure if this a LaTeXStrings, IJulia or Jupyter problem though.

[stevengj]

This is a Jupyter issue.