filter: alpha(opacity=,finishopacity=,style=)??? alpha是来设置透明度的,它的基本属性是filter:alpha(opacity,finishopacity,style,startX,startY,finishX,finishY).opacity代表透明度数,选值0-100,0是完全透明,100是不透明.finishopacity用来设置结束时的透明度,以达到渐变效果.取值范围也是0-100.style指渐变类型,0是无变化,1是线行渐变,2是…