title: Issue with openpyxl while exporting format in excel
body: <p>I am updating my Python Dataframe using <strong>conditional formatting</strong>. Code that I am using is <strong>working fine with Python Dataframe</strong>, however when I export it on Excel (<code>.to_excel</code>) using <code>openpyxl</code>, it <strong>randomly</strong> export conditional formatting by column/field.</p>
  <p>Can you please help in this regard?</p>
  <p>(A) <strong>Code (Sample)</strong> used for formatting:-</p>
  <pre><code>df_formatted = df_to_format.style\
      .applymap (lambda x: 'background-color: %s' %  'purple' if str(x)[0:4] == 'Coun' else 'background-color: %s' % 'none', subset=['Sheet1'])\
      .applymap (lambda x: 'background-color: %s' %  'gray' if str(x)[0:4] == 'This' else 'background-color: %s' % 'none', subset=['Sheet1'])\
      .applymap (lambda x: 'background-color: %s' %  'yellow' if str(x)[0:3] == 'Low' else 'background-color: %s' % 'none', subset=['Sheet1'])\
      .applymap (lambda x: 'background-color: %s' %  'pink' if str(x)[0:4] == 'High' else 'background-color: %s' % 'none', subset=['Sheet1'])\
  .to_excel('styled.xlsx', engine='openpyxl', index=False)
  </code></pre>
  <p>(B) <strong>Expected</strong> Formatting Export</p>
  <p><a href="https://i.stack.imgur.com/td80S.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/td80S.png" alt="enter image description here" /></a></p>
  <p>(C) <strong>Actual</strong> Formatting Export</p>
  <p><a href="https://i.stack.imgur.com/V6znL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/V6znL.png" alt="enter image description here" /></a></p>