It seems the :first-letter don't work

It seem the :first-letter don't work,for example:
```javascript
var html="

1abc

"
var css="h3:first-letter{color:red}"
output=juice.inlineContent(html, css,{inlinePseudoElements:true});
```
but don't find the the `output` include the `first-letter` style.
have any other additional things I want to do?please give me some advise,thanks a lot.

Start by reproducing the provided html, css, and juice.inlineContent example with inlinePseudoElements enabled. Trace how inlineContent handles pseudo-elements and compare the output with the expected first-letter styling; done means the generated output includes that style or clearly documents the limitation.

Written by the indexing model from the issue text.