Colors of page changed without any interference

I am using the free site Origin theme Vantage and I changed all the colors and font sizes in the style.css folder like 4 months ago and now when I am checking back at my site all the colors and font sizes are set back to default. I didn’t change anything and neither did the people with the password. I can’t see to figure out what happened, did this happen to anyone before? It is super strange, is there any way t revert back to the file i changed. Any help would be highly appreciated!

URL: http://www.renusbeautystudio.com