AngleSharp by Florian Rappl

<PackageReference Include="AngleSharp" Version="0.8.1" />

.NET API 1,172,480 bytes

CssBorderTopRightRadiusProperty

sealed class CssBorderTopRightRadiusProperty : CssBorderRadiusPartProperty, ICssBorderTopRightRadiusProperty, ICssProperty

Information can be found on MDN: https://developer.mozilla.org/en-US/docs/Web/CSS/border-top-right-radius

public Length HorizontalTopRight { get; }

public Length VerticalTopRight { get; }