/*** ESSENTIAL STYLES ***/
.sf-menu, .sf-menu * {/*一级菜单与周围元素的距离*/
 margin: 0;
 padding: 0;
 list-style: none;
}
.sf-menu li {
 position: relative;
}
.sf-menu ul {
 position: absolute;
 display: none;
 top: 100%;
 left: 0;
 z-index: 99;
}
.sf-menu > li {
 float: left;
}
.sf-menu li:hover > ul,
.sf-menu li.sfHover > ul {
 display: block;
}

.sf-menu a {
 display: block;
 position: relative;
}
.sf-menu ul ul {
 top: 0;
 left: 95%;/*负责三级菜单的位置*/
}


/*** DEMO SKIN ***/
.sf-menu {
 float: left;
 margin-bottom: 0px;
}
.sf-menu ul {
 box-shadow: 2px 2px 6px rgba(0,0,0,.2);
 min-width: 12em; /* allow long menu items to determine submenu width */
 *width: 12em; /* no auto sub width for IE7, see white-space comment below */
}
.sf-menu a {
 border-left: 0px solid #fff;
 border-top: 0px solid #dFeEFF; /*菜单之间上下间距fallback colour must use full shorthand */
 border-top: 0px solid rgba(255,255,255,.5);
 padding: .75em 1em;
 text-decoration: none;
 zoom: 1; /* IE7 */
}
.sf-menu a {
 color:black;/*菜单字体颜色*/
}
.sf-menu li {
 background:#D3D3D3;/*一级菜单设置背景色*/
 white-space: nowrap; /* no need for Supersubs plugin */
 *white-space: normal; /* ...unless you support IE7 (let it wrap) */
 -webkit-transition: background .1s;
 transition: background .1s;/*背景变换时间*/
}
.sf-menu ul li {
 background: #D3D3D3;/*二级菜单背景颜色*/
}
.sf-menu ul ul li {
 background: #D3D3D3;/*三级菜单背景颜色*/
}
.sf-menu li:hover,
.sf-menu li.sfHover {
 background: #CFDEFF;/*鼠标停放时子菜单颜色*/
 /* only transition out, not in */
 -webkit-transition: none;
 transition: none;
}

/*** arrows (for all except IE7) **/
.sf-arrows .sf-with-ul {
 padding-right: 1.9em;/*一级菜单三角箭头距菜单文字左间距*/
 *padding-right: 1em; /* no CSS arrows for IE7 (lack pseudo-elements) */
}
/* styling for both css and generated arrows */
.sf-arrows .sf-with-ul:after {
 content: '';
 position: absolute;
 top: 50%;
 right: 1em;/*负责菜单三角箭头左右位置*/
 margin-top: -3px;/*负责菜单三角箭头上下位置*/
 height: 0;
 width: 0;
 /* order of following 3 rules important for fallbacks to work */
 border: 5px solid transparent;/*负责三角箭头的大小*/
 border-top-color: #dFeEFF; /* edit this to suit design (no rgba in IE8) */
 border-top-color: rgba(255,255,255,.5);
}
.sf-arrows > li > .sf-with-ul:focus:after,
.sf-arrows > li:hover > .sf-with-ul:after,
.sf-arrows > .sfHover > .sf-with-ul:after {
 border-top-color: white; /* IE8 fallback colour *//*负责一级三角箭头的颜色*/
}
/* styling for right-facing arrows */
.sf-arrows ul .sf-with-ul:after {
 margin-top: -5px;
 margin-right: -3px;
 border-color: transparent;
 border-left-color: #dFeEFF; /*负责一级三角箭头的颜色，edit this to suit design (no rgba in IE8) */
 border-left-color: rgba(255,255,255,.5);
}
.sf-arrows ul li > .sf-with-ul:focus:after,
.sf-arrows ul li:hover > .sf-with-ul:after,
.sf-arrows ul .sfHover > .sf-with-ul:after {
 border-left-color: white;/*负责二级三角箭头的颜色*/
}