With version 0.12 the regex treatment has improved, but I still can’t capture the content with math mode.

I leave a simple example of what I want to capture.

```
#show regex("=+/?(.+)"): it => {
it.fields()
}
=? $display(x^2 -4x +4 = 0)$
```

You can see that the mathematical function is not captured.

Not a perfect solution, but you can move =? inside the math call and use `show math.equation`

instead

```
#show math.equation: it => {
[#if it.body.children.at(0).has("text") and it.body.children.at(0).text == "?=" {
text(red, it)
} else {
text(blue, it)
}]
}
$x^2 -4x +4 = 0$ \
$"?=" x^2 -4x +4 = 0$
```

## Solution

If you’re trying to filter out certain equations, maybe try labeling it:

```
$ x^2 - 4 x + 4 = 0 $ <marked-eq>
```

Then select it by using:

```
#show <marked-eq>: set text(fill: red)
```

## Possible issue

However, currently one element can have at most one label, which would cause problems when you try to use this method together with other `show`

rules that handle labels.