code: public static boolean isValid(final String cssValue) {
          // TODO verify this method. the fontFamily cannot be validated so this
          // method may be invalid. remove after verified
  
          if (cssValue == null || StringUtil.isBlank(cssValue)) {
              return false;
          }
  
          final String[] cssValueParts = getExtractedSubCssValues(cssValue);
  
          FontStyle fontStyle = null;
          FontVariant fontVariant = null;
          FontWeight fontWeight = null;
          FontSize fontSize = null;
          LineHeight lineHeight = null;
          FontFamily fontFamily = null;
  
          for (final String eachPart : cssValueParts) {
              boolean invalid = true;
              if (fontStyle == null && FontStyle.isValid(eachPart)) {
                  fontStyle = FontStyle.getThis(eachPart);
                  invalid = false;
              } else if (fontVariant == null && FontVariant.isValid(eachPart)) {
                  fontVariant = FontVariant.getThis(eachPart);
                  invalid = false;
              } else if (fontWeight == null && FontWeight.isValid(eachPart)) {
                  fontWeight = FontWeight.getThis(eachPart);
                  invalid = false;
              } else if (fontSize == null && FontSize.isValid(eachPart)) {
                  fontSize = new FontSize(eachPart);
                  invalid = false;
              } else if (lineHeight == null && LineHeight.isValid(eachPart)) {
                  lineHeight = new LineHeight(eachPart);
                  invalid = false;
              } else if (fontFamily == null
                      && (!FontFamily.isValidateFontFamilyNameGlobally()
                              || FontFamily.isValid(eachPart))) {
                  fontFamily = new FontFamily(eachPart);
                  invalid = false;
              }
              if (invalid) {
                  return false;
              }
          }
  
          return fontStyle != null || fontVariant != null || fontWeight != null
                  || fontSize != null || lineHeight != null || fontFamily != null;
      }
docs: checks the given css value is valid for this class. It does't do a strict
  validation.
  
  @param cssValue
  @return
  @since 1.0.0
  @author WFF