Nesting #text and #highlight while using gradient

[Jas]

Hi, I’m trying to highlight some formatted text that contains math in my document with some fun colours. I did the following:

#text(fill: olive)[
  Implication: when a function has a left and right inverse, the two inverses are equal. To prove this statement in the general case (without assuming $f, g, h: RR -> RR$), suppose $f: A -> B, g, h: B -> A$. Then $ h compose f compose g \ (h compose f) compose g = g \ h compose (f compose g) = h $ 
  
  Here $g = h = f^(-1)$. #highlight(gradient.linear(..color.map.rainbow))[Caution: $f compose f^(-1): B->B, f^(-1) compose f: A->A$]
]

The compiler is giving me an error:

Error: Expected content, found gradient
How to fix this?

• Replace the gradient.linear(…color.map.rainbow) with content.
• Did you store content in a variable? Insert the variable’s name.

I’m a little confused why this is the case, because I took this syntax from an example in the documentation on highlight and gradient:

This is #highlight(
  fill: blue
)[highlighted with blue].

As a fill to paint the interior of a shape: rect(fill: gradient.linear(..))

If things were working as I expected, everything in the red rectangle should have rainbow highlight:

How do I fix this?

[janekfleper]

When you call highlight(gradient.linear(...)), the argument is interpreted as the body because it is the only positional argument of the highlight function. This what the error is trying to tell you. Use the named argument highlight(fill: gradient.linear(...)) instead to apply the gradient as the fill of the highlight element.

One additional comment regarding highlight and equations. As you can already see in your second image, the highlight only covers the text. If you want the gradient to extend to the end of the equation, you can wrap everything in a box and set the fill with the linear gradient. You need to play around with the vertical size a bit to make sure that the box has the same extent as the highlight.