background "<bg-position> / <bg-size>" syntax unsupported

[mganss]

Prerequisites

• Can you reproduce the problem in a MWE?
• Are you running the latest version of AngleSharp.Css?
• Did you check the FAQs to see if that helps you?
• Are you reporting to the correct repository? (there are multiple AngleSharp libraries, e.g., AngleSharp.Xml for Xml support)
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Description

The syntax for background specifying both position and size separated by a slash is unsupported. #124 seems to be related.

This was initiallly reported as mganss/HtmlSanitizer#536

Steps to Reproduce

var html = @"<div style=""background: center / cover;""></div>";
var conf = Configuration.Default.WithCss(new CssParserOptions
{
    IsIncludingUnknownDeclarations = true,
    IsIncludingUnknownRules = true,
    IsToleratingInvalidSelectors = true,
});
var parser = new HtmlParser(new HtmlParserOptions { IsScripting = true }, BrowsingContext.New(conf));
var dom = parser.ParseDocument(html);
var elem = dom.QuerySelector("div");
var style = elem.GetStyle();
var styleCount = style.Count(); // -> 0

Expected Behavior

The number of styles is nonzero.

Actual Behavior

The number of styles is zero.

Possible Solution / Known Workarounds

No response

[ikesnowy]

Getting same problem here, I believe it's because the / is not been skipped by calling SkipSpacesAndComments:

AngleSharp.Css/src/AngleSharp.Css/Declarations/BackgroundDeclaration.cs

Line 130 in 459b48c

size = source.ParseSize();

Debugger page: