Make an element's height be "The rest of the page"

[vernal zephyr]

I'd like to place a heading, and then a figure. Both together should occupy together one page. Is there some way to lay them out so that they do so?

I tried the following:

#box([
== Fase de planteamiento y resolución del problema de automatización
#figure(
  image("main.png")
, caption: [Programa principal del autómata.])
])
``` But this seems to ignore page margins:

[fluid island]

you can use 1fr as a height measurment

each element using fr measurements gets the fraction of the remaining space and all fractional measurements

i.e. if there is one it gets all the remaining space

if there are multiple their fractions are added and they receive their fraction of the remaining space

?render ```
#set page(height: 100pt)
#grid(rows: (1fr, 1fr, 2fr),
block(height: 100%, fill: gray, lorem(10)),
block(height: 100%, fill: red, lorem(10)),
block(height: 100%, fill: green, lorem(10)),
)

[fluid island]

hmm, it appears that only works for spacing

so here you can see that the remaining space (100pt) is partitioned into 3 parts with fractional lengths 1:1:2, that means the first 2 elements are the same size and the third one is twice as large as the first/second one

but all space is filled

minus page/grid margin

[vernal zephyr]

But that means I would need to set the relationship of height between the heading and the image

No?

[fluid island]

Those lengths given in the grid can also be absolute or auto

?render ```
#set page("a4")
#grid(rows: (auto, 1fr),
block(height: 20pt, fill: green, lorem(10)),
block(height: 100%, fill: red, lorem(200)),
)

[fluid island]

And if you had two 1fr elements they eoudl split the red part equally