Upgrade to 7.0.0 breaks CSS?

Has anyone else seen this? I upgraded to the new markdown-pdf 7.0.0 in order to get the new links-in-PDFs behavior, only to find that now my CSS is broken. As in, either markdown-pdf or PhantomJS (can't tell which) just isn't looking at my CSS file at all anymore. The output is exactly the same as if I take the `cssPath` value out of my markdown-pdf `options` entirely.

I have changed literally nothing in my app. All I did was `npm update markdown-pdf`, and wham, CSS is busted. I've double-checked that the CSS file really is still there, et cetera. Here's how I'm invoking markdown-PDF:

```
fileList = buildFileList() // collect file information from src/documents/*.md
var options = {
preProcessMd: preProcessMd,
cssPath: "src/static/styles/default.css",
remarkable: {
html: true
}
}

markdownpdf(options)
.concat.from(
fileList.map(function(val){ return val.path } )
)
.to(getOutputFilename(fileList[0].title), function () {
console.log("Done.")
})
```