title: highlight (color) a panda data frame row by index
body: <p>i have two data frame df1:</p>
  
  <pre><code>d1 = {"col1" : ['A', 'B', 'C'],
        "Col2": ["home", "car","banana" ]}
  
  d2 = {"col1" : ['D', 'F','C'],
        "Col2": ["garden", "boat","banana" ]}
  
  df1 = pd.DataFrame(data=d1)
  df2 = pd.DataFrame(data=d2)
  
  new_df = pd.merge(df1, df2,  on ='col1', how='outer')
  new_df
  </code></pre>
  
  <p>So what I am trying to do is highlight the third row "banana" that was found in the two data frames.
  I was using the <a href="https://pandas.pydata.org/pandas-docs/stable/style.html" rel="noreferrer">Styling documentation</a> to find a solution but no luck.
  I was able to highlight only a single row, but when I have multiple rows it doesn't work.
  Please give a helping hand </p>