CSS2 Element 의 투명도

1. filter:alpha(opacity=x)

IE8 and earlier use filter:alpha(opacity=x). The x can take a value from 0 - 100. A lower value makes the element more transparent.

Reference : http://www.w3schools.com/Css/css_image_transparency.asp

2. -khtml-opacity

khtml opacity, old safari

Reference : http://www.java2s.com/Code/HTMLCSS/IE-Firefox/SafariKHTMLproprietaryopacityproperty.htm

3. -moz-opacity

Mozilla, Netscape

4. opacity

IE9, Firefox, Chrome, Opera, and Safari use the property opacity for transparency. The opacity property can take a value from 0.0 - 1.0. A lower value makes the element more transparent.

* 결론

Div {

filter:alpha(opacity=50); -khtml-opacity: 0.5; -moz-opacity: 0.5; opacity: 0.5;

}