fix PropertySkip value missing px wrap (#26)

src/Css/Functions.cs

@@ -11,6 +11,7 @@ internal static string FormatValue<T>(string key, T value)
             float v => Wrap(key, v, v != 0),
             double v => Wrap(key, v, v != 0),
             Keyframe v => v.ToString(),
+            PropertySkip v => v.GetValue(key),
             _ => value?.ToString()
         };
     }

src/Css/IProperty.cs

@@ -8,7 +8,14 @@ public interface IProperty
     public struct PropertySkip
     {
         public bool SkipCheck { get; set; }
+
         public Property<string, double> Value { get; set; }
+
+        public string GetValue(string key)
+        {
+	        return Value.GetValue(key);
+        }
+
         public override string ToString()
         {
             return Value.ToString();

test/CssInCSharp.Tests/CSSObjectTests.cs

@@ -80,5 +80,24 @@ public void Animation()
             });
             messageMoveIn.ToString().ShouldBe("MessageMoveIn;@keyframes MessageMoveIn{0%{padding:0;transform:translateY(-100%);opacity:0;}100%{padding:100px;transform:translateY(0);opacity:1;}}");
         }
-    }
+
+		[Fact]
+		public void Should_Property_Skip_Pxwrap()
+		{
+			new CSSObject()
+			{
+				[".test"] = new CSSObject()
+				{
+                    Left = new PropertySkip()
+                    {
+                        SkipCheck = true,
+                        Value = 12
+                    }
+				}
+			}
+			.ToString()
+			.ShouldBe(".test{left:12px;}");
+		}
+
+	}
 }