title: Defining different pandas xlsxwriter border types
body: <p>I would like to define different strengths for bottom-borders with xlsxwriter. My question is: How can I prevent the thick-bottom-HEADER-border from being overwritten in the example below? 
  I would like to note, that if I start one row later with the conditional format, I get one row without bottom borders.</p>
  
  <pre><code>import numpy as np
  import pandas as pd
  
  dates = pd.DataFrame(pd.date_range('2000-01-01', periods = 15), columns = ['date'])
  d = pd.DataFrame(np.random.randint(1, 5, (15, 3)), columns = list('abc'))
  d = pd.concat([dates, d], axis = 1)
  
  writer = pd.ExcelWriter('dates_border.xlsx',
                      #OR: 'c:\\users\\USER_NAME\\desktop\\dates_border.xlsx',
                      datetime_format='yyyy.mm') 
  d.to_excel(writer, 'Sheet1', index = False)
  worksheet = writer.sheets['Sheet1']
  workbook  = writer.book
  
  # header: I LOSE THE THICK BOTTOM BORDER OF THE HEADER
  header_format = workbook.add_format({'bottom': 2, 'bg_color': '#F9DA04'})
  for col_num, value in enumerate(d.columns.values):
  worksheet.write(0, col_num, value, header_format)
  
  # data with bottom borders
  format1 = workbook.add_format()
  format1.set_bottom(7)
  
  worksheet.conditional_format(1, 0, d.shape[0], d.shape[1] -1,
  {'type': 'cell',
   'criteria': '&lt;&gt;',
   'value': '""',
   'format': format1})
  
  writer.save()
  </code></pre>
  
  <p>Thx &amp; kind regards</p>