I have inherited a CSS file which I need to make some simple additions to but not mess up the existing.

I have found this:

.box {
*margin-left:-5px;
}

What is the '*' ?

Also, it breaks some really old browsers (mainly mobile) which won't render at all. Taking it out and they work.

Also, how should I get around this as I'm guessing it's there for a reason. Can I keep it in and stop it breaking old mobiles?