Replacement for

text-align: center is what you should use. In fact, the ideal way is this:

.center {
    text-align: center;
}
.center > div, .center > table /* insert any other block-level elements here */ {
    margin-left: auto;
    margin-right: auto;
}

Obviously, it’s not quite as simple as you might hope for.

Personally, I just use:

.center {text-align: center;}
.tmid {margin: 0px auto;}

Then apply classes where needed.