title: Tooltips style in google charts
body: <p>I would like to know if it is possible to change the font color of DEFAULT tooltips in a google line chart.</p>
  
  <p>I want to do this by changing css style like this:</p>
  
  <pre><code>&lt;style&gt;
  
      .google-visualization-tooltip { 
  
              width: 150px !important;
              border: none !important;
              border-radius: 21px !important;
              background-color: rgb(30, 50, 230)!important;
              position: absolute !important;
              box-shadow: 7px 7px 5px 0px rgba(50, 50, 50, 0.75) !important;
              background: -moz-linear-gradient(30deg, rgb(30, 50, 230) 30%, rgb(90, 140, 250) 70%) !important;
              background: -webkit-linear-gradient(30deg, rgb(30, 50, 230) 30%, rgb(90, 140, 250) 70%) !important;
              background: -o-linear-gradient(30deg, rgb(30, 50, 230) 30%, rgb(90, 140, 250) 70%) !important;
              background: -ms-linear-gradient(30deg, rgb(30, 50, 230) 30%, rgb(90, 140, 250) 70%) !important;
              background: linear-gradient(120deg, rgb(30, 50, 230) 30%, rgb(90, 140, 250) 70%) !important;
              font-size:  10px !important;
  
            }
  
  
      &lt;/style&gt;
  </code></pre>
  
  <p>All of this css lines work well but I have not found the font color param until now. </p>
  
  <p>By the way, if I modify "tooltip.textStyle" param of <a href="https://developers.google.com/chart/interactive/docs/gallery/linechart" rel="noreferrer">Line Chart API</a> the font color changes but the CSS code mentioned above become unusable.</p>
  
  <p>Thanks!</p>