AngleSharp by Florian Rappl

<PackageReference Include="AngleSharp" Version="0.3.6" />

.NET API 582,656 bytes

 CSSKeyframeRule

public sealed class CSSKeyframeRule : CSSRule
Represents a CSS @keyframe rule.
public string KeyText { get; set; }

Gets or sets the key of the keyframe, like '10%', '75%'. The from keyword maps to '0%' and the to keyword maps to '100%'.

public CSSStyleDeclaration Style { get; }

Gets a CSSStyleDeclaration of the CSS style associated with the key from.