Reduce hight of frame in flexdashboard / storyboard

Im working on a flexdashboard / storyboard where I would like to reduce the hight for each of the frames. Is that possible?

Example code:

---
title: "Flex"
output: 
  flexdashboard::flex_dashboard:
    orientation: columns
    vertical_layout: fill
---

```{r setup, include=FALSE}
library(flexdashboard)
```
G1 {.storyboard}
===================================================

### Frame 1

Some text and code

### Frame 2

Some text and code

G2
===================================================

### Row 1

### Row 2

I.e. remove the empty area as below:

Thanks!