code: public static boolean isNumberValue (@Nullable final String sCSSValue)
    {
      final String sRealValue = StringHelper.trim (sCSSValue);
      return StringHelper.hasText (sRealValue) && StringParser.isDouble (sRealValue);
    }
docs: Check if the passed value is a pure numeric value without a unit.
  
  @param sCSSValue
  The value to be checked. May be <code>null</code> and is
  automatically trimmed inside.
  @return <code>true</code> if the passed value is a pure decimal numeric
  value after trimming, <code>false</code> otherwise.