Blogdown and Streamgraph

It's hard to know for sure, since you are not providing a REPRoducible EXample (reprex), but I suspect that your problem is with the YAML header for your .Rmd file instead of your code for the steamgraph.

Take a look at this example.

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

```{r setup, include=FALSE}
library(flexdashboard)
library(dplyr)
library(babynames)
library(streamgraph)
```

Column {data-width=650}
-----------------------------------------------------------------------

### Chart A

```{r}
babynames %>%
  filter(grepl("^Kr", name)) %>%
  group_by(year, name) %>%
  tally(wt=n) %>%
  streamgraph("name", "n", "year")
```

Column {data-width=350}
-----------------------------------------------------------------------

### Chart B

```{r}
babynames %>%
  filter(grepl("^I", name)) %>%
  group_by(year, name) %>%
  tally(wt=n) %>%
  streamgraph("name", "n", "year", offset="zero", interpolate="linear") %>%
  sg_legend(show=TRUE, label="I- names: ")
```

### Chart C

```{r}
plot(iris)
```

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