One date always changing

Hi
So there is a website with a datepicker that i can only pick one day
Using Xpath isnot useful here as the available day is always changing.
Using inspect elements I noticed that the available day is using “class=active.day”
Is there any way to automate the click using specific class ?

I have a same problem, but it’s somthing like this.
I have to choose the day that is today. And to do that, I have to click on a button to show a calendar. But the xpath is alway changing, when all I need is Today. So I look into the xpath, and see that there is a number in the xpath that change in a rule. So I got that rule to put it in my command.

You should pick a serveral days to see if there is a rule in your xpath. If not, please show your webiste so the guys in here could dig deeper.