Error character problems caused by pseudo-class content being escaped

[ZaneL1u]

Hello!

I found in my use that once the content of the pseudo-class has the '\' symbol, it will be escaped to the wrong '' character, which is reproduced below.

.iconfont:before {
  content: "\e600";
}

Then run:

const cssAST = csstree.parse(css)
const finalCSS = csstree.generate(cssPlain)

In the generated CSS, the expected result is escaped and will look like this:

.iconfont:before{content:""}

[thescientist13]

Just ran into this issue as well.

Here is a link to astexplorer.net that reproduces the issue
https://astexplorer.net/#/gist/fe3f7886b4638ffc5bf66275c54d3af5/d503c4abef9da04298ffeccba4fdaef733e34858

[thescientist13]

Just bumped into this again while experimenting with FontAwesome, which makes pretty heavy use of this pattern
https://unpkg.com/browse/@fortawesome/fontawesome-free@6.6.0/css/fontawesome.css

.fa-circle-chevron-right::before {
  content: "\f138";
}