Dear sir,
I'm sorry for this comment.
It's not a difficult task to make a page fully responsive within a hour for an expert but I think it's totally impossible if you think about quality.
Because, it needs to check through different types of devices & different types of browser.
In many cases the debugger or inspector doesn't show the actual value.
So, if you think 2~3 days is ok for you, you can think about me.
With regards,
Md Biplob Hossain