.opacite_css{ float:left; width:30%; margin-right:1%; padding:5px 1%; text-align:center; color:#fff; background-color:#000; font-weight:bold; } #opacite_css_1:hover{ /* -webkit : Chrome, Safari, Android -khtml : Konqueror -moz : Firefox et Mozilla -ms : Internet Explorer -o : Opera */ -webkit-opacity:0.4; -khtml-opacity:0.4; -moz-opacity:0.4; -ms-opacity:0.4; -o-opacity:0.4; opacity:0.4; filter:alpha(opacity=40); } #opacite_css_2:hover{ background-color:rgba(0,0,0,0.4); } #opacite_css_3:hover{ background-color:rgba(0,0,0,0.4); -webkit-transition:background-color 0.3s ease; -khtml-transition:background-color 0.3s ease; -moz-transition:background-color 0.3s ease; -ms-transition:background-color 0.3s ease; -o-transition:background-color 0.3s ease; transition:background-color 0.3s ease; }