CSS changes don't update in safari and firefox

Hi,
I was working on a wordpress site a week ago, and it was no problem making changes in the css. I’m working with testing servers from MAMP.

The css changes would show up in safari, firefox and chrome without a problem. Then I ran into a problem so I reinstalled a fresh version of MAMP and wordpress, and copied my code. But now it doesnt show in safari and firefox (the old styling from wordpress keeps showing). But the changes do show in chrome.

The changes I make in the php documents do show in all browsers by the way.

I also tried a new wordpress site, changed only a couple of things like a border, a color change, but still, nothing happening in safari and firefox…

Any idea how to fix this? It doesnt have anything to do with refreshing the pages. I erased the history several times, but that doesnt do the trick.

Also, when searching the web to fix this, I found something about ISP and firewall issues, but I don’t know what to do with that info…