Openpyxl border

Code

import openpyxl
from openpyxl.styles import Border,Side

#  Import fill class PatternFill
wb = openpyxl.load_workbook('/Users/test0712.xlsx')
ws = wb['Sheet1']
max_rows = ws.max_row  #  Get the largest row 
max_columns = ws.max_column  #  Get the largest column 


borders = Border(left=Side(style='thick'),bottom=Side(style='thick'),right=Side(style='thick'),top=Side(style='thick'))  #  Set the fill color to pink 

# openpyxl Subscript from 1 Start 
for i in range(1, max_rows + 1):
    for j in range(1, max_columns + 1):
        ws.cell(i, j).border = borders

wb.save('/Users/test0712.xlsx')

Before filling

After filling