The biggest lack compared to my normal Latex usage is a `\mathrm` command or similar. For example I believe the chemical elements should be set in upright, not italic.

I just added mathrm{...your text...} and text{...your text...} to write upright text :)

It was puzzling that it showed "LaTeX: [empty small box]". I was waiting for something to load in that box before I realized that it would be replaced by the transormed output from whatever I typed above.

I don't know much about web design but for stuff like this I usually see the text box filled with an example input and the resulting output is displayed along with it.

I changed it so that it only shows the LaTeX box when you type something in.

delta produces \Delta instead of \delta, so there is no way to get \delta.

Is there a way to produce <= and >=? lt and gt become < and >, which is not so necessary seeing that < and > work fine, but lte and gte do not become \lte or \gte.

In the product prod example, there is nlogn in the source and logi in the rendering.

Ok I added <=, >= to produce \lte and \gte.

Also delta produces \delta instead of \Delta.

\ne is also missing.

Some equations are invalid LaTeX, such as `x_{1+x}_2`, but show up with translations regardless.

Not seeing it.