Python/With selenium, trying to express a xpath for a color so all buttons matching the color can be clicked

Question

I'm currently working with Selenium and Python to create a script that helps with booking free spots on a website for internships so you don't have to check it all the time.

So I'm trying to express an xpath for a color which is used in a data cell element to mark any available spots. In the end I want to use this xpath in selenium so it can be clicked. Now I got the problem that I can't locate the color in the HTML source. I used the "color digital meter" in apple to find out the color(please see the picture attached) but can't locate the element in the HMTL. I also searched most of the HTML code by hand. Am I missing something? Thanks in advance! Screenshot of website

Link to HTML Code: http://filedropper.com/FRGJDgha

browser.get('https://www.pj-portal.de/index_hro.php?PAGE_ID=101')

delay = 2

browser.find_elements_by_xpath("//*[starts-with(text(),'1/')]")
print("found")
Liste1 = browser.find_elements_by_xpath("//*[starts with(text(),'1/')]")
print(len(Liste1))

I tried it with a xpath targeting a text attribute that shows the available spots and the total spots but I figure targeting the green color would be the neater solution.