代码如下，怎么让字体加粗？
#menumain{
margin:0;
white-space:nowrap;
overflow:hidden;
height:34px;
}
#menumain .mainmenuiner {
height:34px;
padding:0;
line-height:34px;
overflow: hidden;
margin: 0px;
}
#menumain a.menumain:link,#menumain a.menumain:active,#menumain a.menumain:visited{
display:block;
float:left;
height:34px;
text-decoration: none;
text-align:center;
width:100px;
color:#fff;
font:18px/30px 'SimSun',Arial,Sans-Serif;
background:url(menu.jpg) 0px 0px no-repeat;
margin:0px;
}
#menumain a.menumain:hover{
display:block;
float:left;
height:34px;
color:#eee;
text-decoration: none;
text-align:center;
width:100px;
font:18px/30px 'SimSun',Arial,Sans-Serif;
background:url(menu.jpg) 0px 0px no-repeat;
margin:0px;
}
#menumain a.menumain_current{
display:block;
float:left;
height:34px;
color:#000;
text-decoration: none;
text-align:center;
width:100px;
font:18px/39px 'SimSun',Arial,Sans-Serif;
background:url(menu.jpg) 0px 0px no-repeat;
margin:0px;
}