Semi-advanced optimization

[danbeam]

I'd like to use shorthand rules safely when possible

#id { margin: 10px 20px 10px 20px; }

should become

#id { margin: 10px 20px; }

NOTE: I don't want to accidentally override rules by using shorthand that is too generic:

.class { background-color: red; }

If we could verify this is the only selector that applies to this rule, we could safely change this to:

.class { background: red; }

but it's very hard to know how this will affect things.