Pandas change cell color

Question

I am trying to change the cell colour if the cell contains a string from a list of strings:

This allows me to change the colour if there is a match but it doesn't appear to go through every item in the list it only does the first match (i think this is because of the ==)

def color_negative_red(val):
    for technique in techniques:
        color = 'green' if val == technique else 'black'
        return 'color: %s' % color

I am trying the following but that doesn't appear to be changing any colours:

def color_negative_blue(val):
    for technique in techniques:
        color = 'blue' if technique in val else 'black'
        return 'color: %s' % color

I call these functions as followed:

s = df1.style.applymap(color_negative_blue)

I want to be able to go over a list of items and if the item from the list exists then change the colour of that text in the cell.

DataFrame:

Column1                Column2              Column3          Column4

Acquire               Infrastructure        Botnet      Drive-by Compromise 
DNS Server                                               Exploit Public-Facing Application  
Domains                                                 External Remote Services    
Server                                                  Hardware Additions  
Virtual Private Server                    Phishing      Spearphishing Attachment
Web Services                              Spearphishing Link
Compromise Accounts Email Accounts                      Spearphishing via Service
Social Media Accounts                                   Replication Through Removable Media 


techniques = ['Server','Web Services', 'Phishing']

Answer 1

def my_func_blue(val):
    if val in techniques:
        color = 'green'
        return f'background-color: {color}'
    else:
        color = 'red'
        return f'background-color: {color}'

the above code allows me to carry out the searches and change the color of the cell that it has matched on