Is a CSS property starting with a hash (#) valid?

Question

What does the following CSS do and is it valid?

h4 {
    width: 83%;
    #width: 75%;
}

Answer 1

To basically answer both your questions.

• The # before the property targets IE7 & IE6 (and lower)
• No, it's not valid.

I asked the same question, there's more info there that may be helpful to others:

Post: " CSS - "#" sign before property "