# Display of Calligraphic Font by MathJax in Chromium

## Background

### CSS style of this blog

I use Solarized theme with light background. IMHO, it is less tiring to look at a light background. I’ve chosen pink as the text colour.

### Contents of this blog

Apart from technical stuff, I often post math containing calligraphic font, for example

I used Mozilla Firefox, and I didn’t see problem on the display of \mathcal.

## Problem

Three months ago, I wrote something about Zorn’s Lemma and Hausdorff spaces. In the post Normal Compact $T_2$ Spaces, I observed that the math display was abnormal. Due to homework and exams, I delayed the investigation into this technical problem.

Normally, the foreground colour of the math expression is the same as that of normal inline text. In the above figure, "$T_2$" is in pink. However, $U_y, V_y$ aren’t.

## Discussion

### Look into the code

It is normal for me to inspect the HTML elements.

#### Interpreted HTML in Chromium

The above math expression is in black rather than pink because it is rendered as a PNG image.

I confirmed this by looking at the list of loaded resources.

### Is this problem browser-specific?

I tried opening the blog article in Mozilla Firefox, and I didn’t see any problem.

## Cause

Based on the above observations, I suspected that the presence of a calligraphic font triggered this fallback of fonts. In order to test this, I did an experiment on my local MathJax test page: I had a math expression containing \mathcal and one without. I put them in different order, and observed the difference in the loaded PNG.

### Calligraphic font at the bottom

Only the curly ‘C’ is loaded as PNG, while the rest aren’t.

### Calligraphic font at the bottom

Everything (after the curly ‘C’) are loaded as PNG.

Therefore, my claim is verified. Unluckily, I failed to find any solution to this problem on Google.

## Reasons for not finding a solution

1. This problem doesn’t affect the content.
2. This problem is browser-specific—it doesn’t appear in Mozilla Firefox.
3. It is possible that this issue will be automatically fixed by a future upgrade, and a solution of this problem will be transient.

I’ve better solve math problems instead of technical ones since math is always true.

## Some off-topic stuff

I started writing this post on Christmas Eve, and I finished it at Christmas.