code: public static boolean isValid(final String cssValue) {
          final String trimmedCssValue = StringUtil.strip(cssValue).toLowerCase();
          final String[] cssValueParts = StringUtil.splitBySpace(trimmedCssValue);
          if (cssValueParts.length > 4) {
              return false;
          }
          for (final String cssValuePart : cssValueParts) {
              boolean invalidValue = true;
              for (final CssLengthUnit cssLengthUnit : CssLengthUnit.values()) {
                  final String unit = cssLengthUnit.getUnit();
                  if (cssValuePart.endsWith(unit)) {
                      final String valueOnly = cssValuePart.replaceFirst(unit,
                              "");
                      try {
                          Float.parseFloat(valueOnly);
                      } catch (final NumberFormatException e) {
                          break;
                      }
                      invalidValue = false;
                      break;
                  }
              }
              if (PREDEFINED_CONSTANTS.contains(cssValuePart)) {
                  invalidValue = false;
              }
              if (invalidValue) {
                  return false;
              }
          }
          return true;
      }
docs: validates if the given cssValue is valid for this class.
  
  @param cssValue
  the value to check.
  @return true if valid and false if invalid.
  @author WFF
  @since 1.0.0