code: public static boolean isValidCSS (@Nonnull final String sCSS, @Nonnull final ECSSVersion eVersion)
    {
      ValueEnforcer.notNull (sCSS, "CSS");
  
      return isValidCSS (new NonBlockingStringReader (sCSS), eVersion);
    }
docs: Check if the passed String can be resembled to valid CSS content. This is
  accomplished by fully parsing the CSS file each time the method is called.
  This is similar to calling {@link #readFromString(String, ECSSVersion)} and
  checking for a non-<code>null</code> result.
  
  @param sCSS
  The CSS string to scan. May not be <code>null</code>.
  @param eVersion
  The CSS version to use. May not be <code>null</code>.
  @return <code>true</code> if the CSS is valid according to the version,
  <code>false</code> if not