update gradient color stop validity check

lib/color/color.go

@@ -512,7 +512,19 @@ var NamedColors = []string{
 var ColorHexRegex = regexp.MustCompile(`^#(([0-9a-fA-F]{2}){3}|([0-9a-fA-F]){3})$`)
 
 func ValidColor(color string) bool {
-	if !go2.Contains(NamedColors, strings.ToLower(color)) && !ColorHexRegex.MatchString(color) && !IsGradient(color) {
+
+	if IsGradient(color) {
+		gradient, err := ParseGradient(color)
+		for _, colorStop := range gradient.ColorStops {
+			_, err = csscolorparser.Parse(colorStop.Color)
+			if err != nil {
+				break
+			}
+		}
+		return err == nil
+	}
+
+	if !go2.Contains(NamedColors, strings.ToLower(color)) && !ColorHexRegex.MatchString(color) {
 		return false
 	}
 

lib/color/gradient.go

@@ -9,8 +9,6 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
-
-	"github.com/mazznoer/csscolorparser"
 )
 
 type Gradient struct {
@@ -243,15 +241,10 @@ func UniqueGradientID(cssGradient string) string {
 	return "grad-" + hash
 }
 
+var GradientRegex = regexp.MustCompile(`^(linear|radial)-gradient\((.+)\)$`)
+
 func IsGradient(color string) bool {
-	gradient, err := ParseGradient(color)
+	return GradientRegex.MatchString(color)
-	for _, colorStop := range gradient.ColorStops {
-		_, err = csscolorparser.Parse(colorStop.Color)
-		if err != nil {
-			break
-		}
-	}
-	return err == nil
 }
 
 var URLGradientID = regexp.MustCompile(`^url\('#grad-[a-f0-9]{40}'\)$`)