title: GEB: How to disable CSS errors and warning?
body: <p>I have the following GEB scriptings:</p>
  
  <pre><code>@Grapes([
      @Grab(group='org.gebish', module='geb-core', version='0.9.3'),
      @Grab(group='org.seleniumhq.selenium', module='selenium-htmlunit-driver', version='2.42.2'),
      @Grab(group='org.seleniumhq.selenium', module='selenium-support', version='2.42.2'),
      @Grab(group='log4j', module='log4j', version='1.2.17')
  ])
  ...
  public static void main(String[] args) {
      def config = new ConfigSlurper().parse(new File('log4j.groovy').toURL())
      PropertyConfigurator.configure(config.toProperties())
      Browser browser_ = new Browser()
      ...
  </code></pre>
  
  <p>and the following log4j.groovy:</p>
  
  <pre><code>// log4j.groovy
  log4j {
      rootLogger="DEBUG, A1"
      appender.A1 = "org.apache.log4j.ConsoleAppender"
      appender.'A1.layout' = "org.apache.log4j.PatternLayout"
      if (System.properties['env'] == 'prod') {
          appender.'A1.layout.ConversionPattern'="prod %-4r [%t] %-5p %c %x - %m%n"
      } else {
          appender.'A1.layout.ConversionPattern'="dev %-4r [%t] %-5p %c %x - %m%n"
      }
      logger.org.apache.http = "fatal"
      logger.com.gargoylesoftware = "fatal"
  }
  </code></pre>
  
  <p>Nevertheless I'm constantly having the following messages on the stderr:</p>
  
  <pre><code>Sep 22, 2014 4:46:22 PM com.gargoylesoftware.htmlunit.DefaultCssErrorHandler error
  WARNING: CSS error: 'http://127.0.0.1/www.tatonka.ru/media/css/addons505f.css?t=0612' [93:19] Error in style rule. (Invalid token ":". Was expecting one of: &lt;EOF&gt;, &lt;S&gt;, &lt;NUMBER&gt;, "inherit", &lt;IDENT&gt;, &lt;STRING&gt;, &lt;PLUS&gt;, &lt;COMMA&gt;, &lt;HASH&gt;, &lt;IMPORTANT_SYM&gt;, &lt;EMS&gt;, &lt;EXS&gt;, &lt;LENGTH_PX&gt;, &lt;LENGTH_CM&gt;, &lt;LENGTH_MM&gt;, &lt;LENGTH_IN&gt;, &lt;LENGTH_PT&gt;, &lt;LENGTH_PC&gt;, &lt;ANGLE_DEG&gt;, &lt;ANGLE_RAD&gt;, &lt;ANGLE_GRAD&gt;, &lt;TIME_MS&gt;, &lt;TIME_S&gt;, &lt;FREQ_HZ&gt;, &lt;FREQ_KHZ&gt;, &lt;PERCENTAGE&gt;, &lt;DIMENSION&gt;, &lt;URI&gt;, &lt;FUNCTION&gt;, "}", ";", "/", "-".)
  Sep 22, 2014 4:46:22 PM com.gargoylesoftware.htmlunit.DefaultCssErrorHandler warning
  WARNING: CSS warning: 'http://127.0.0.1/www.tatonka.ru/media/css/addons505f.css?t=0612' [93:19] Ignoring the following declarations in this rule.
  </code></pre>
  
  <p>Please help me to disable them!</p>