How to use Beautiful soup in Python to find a particular text in a particular column

Question

I am working with Python to generate some nice HTML styled with CSS. Right now I would like to add tooltip where the cells are missing in a particular column. I encoded the missing cells in a empty string like this -> "" before rendering the HTML with Pandas. I would like to leverage on the use of Beautiful Soup in Python to capture those missing cells in a particular column.

You can think of the HTML like the image below, where I am interested in capturing the cells encoded with "" ie missing cells in col4

Here is my idea inspired from here:

import re
soup = BeautifulSoup(styler.render(), "html.parser")
columns = soup.findAll('td', text = re.compile(''))
columns

Viewing the columns object in Python shows that it captures the whole cells in a row where col4 is encoded with "". I would instead like to capture only those cells in just col4 that is encoded in "" so that I can easily implore other ways to add a tooltip to the cell.

I welcome other efficient ways to do this instead. Your thoughts, ideas, and references are all welcome.

Many thanks

EDIT:

Jack suggested I access the Pandas DataFrames to capture the missing cells. I already did this earlier and this did not work, here what I did:

empcells = df["col4"][df["col4"] == ""]

styles = [
    #table properties
    dict(selector="", 
         props=[("margin","0"),
                ("font-family",'calibri'),
                ("font-size", "20px"),
                ("border-collapse", "collapse"),
                ("border", "2px solid #ccf"),
                ('text-align', 'center'),
                ("width", "auto !important"),
                ("overflow", "hidden")
                   ]),

     # drop down menu
     dict(selector="select", 
          props=[("width", "100%"),
                 ("height", "24px"),
                 ("border-radius", "15px"),
                 ("box-shadow", "0 5px 25px rgba(0, 0, 0, 0.3)")]),

    dict(selector="td %s" %(empcells),
         props=[
            ("display", "inline"),
            ("position", "relative"),
            ("background", "#333"),
            ("background", "rgba(0,0,0,.8)"),
            ("border-radius", "5px)"),
            ("bottom", "26px"),
            ("color", "#fff"),
            ("left", "20%"),
            ("padding", "5px 15px"),
            ("position", "absolute"),
            ("z-index", "98"),
            ("width", "220px")
         ]),

    #header color - optional
    dict(selector="thead", 
         props=[("background-color","#104374"),
                ("padding", ".1em"),
                ("position", "sticky"),
                ("top", "0")
               ]),

    dict(selector="tbody", 
         props=[("overflow-x","hidden")
               ]),

    #background shading
    dict(selector="tbody tr:nth-child(even)",
         props=[("background-color", "#fff")]),
    dict(selector="tbody tr:nth-child(odd)",
         props=[("background-color", "#eee")]),


    #cell spacing
    dict(selector="th, td", 
         props=[("padding", "2px"),
               ('text-align', 'center')]),

    #header cell properties
    dict(selector="th", 
         props=[("font-size", "30%"),
                ("background-color","#104374"),
                ("color", "white"),
                ("font-size", "20px"),
                ("padding", ".6em"),
                ("text-align", "center"),
                ("position", "sticky"),
                ("top", "0"),
                ("margin","0")]),

    #render hover last to override background-color
    hover()
]

Correct me if something is not right.