css - CSS - 更改当前页面链接的背景图片

Question

嘿，有人可以帮忙吗，我一直在绕圈子。我想更改当前页面上链接的背景图片。这是我的CSS。谢谢

/* button1 */
#header  ul li.item-101 a {width:140px; height:56px; background:url(../images/buttonBlack.png) no-repeat;}
#header  ul li.item-101 a:hover,
#header  ul li.item-101 a.active {background:url(../images/buttons_03.png) no-repeat;}

/* button2 */
#header  ul li.item-102 a {width:140px; height:56px; background:url(../images/buttonBlack.png) no-repeat;}
#header  ul li.item-102 a:hover,
#header  ul li.item-102 a.active {background:url(../images/buttons_03.png) no-repeat;}

/* button3 */
#header  ul li.item-103 a {width:140px; height:56px; background:url(../images/blackbuttonlong.png) no-repeat;}
#header  ul li.item-103 a:hover,
#header  ul li.item-103 a.active {background:url(../images/blueButtonLong.png) no-repeat;}

/* button4 */
#header  ul li.item-104 a {width:92px; height:56px; background:url(../images/buttonBlack.png) no-repeat;}
#header  ul li.item-104 a:hover,
#header  ul li.item-104 a.active {background:url(../images/buttons_03.png) no-repeat;}

/* button5 */
#header  ul li.item-105 a {width:92px; height:56px; background:url(../images/buttonBlack.png) no-repeat;}
#header  ul li.item-105 a:hover,
#header  ul li.item-105 a.active {background:url(../images/buttons_03.png) no-repeat;}