按著視頻敲的 為什么三級菜單的小箭頭不顯示呢
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.top-nav ul ul{
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2018-09-19
.top-nav ul ul li:first-child a:before{
left: :-6px;
top: 50%;
margin-top: -6px;
border-left: 0;
border-bottom: 6px solid transparent;
border-top: 6px solid transparent;
border-right: 6px solid #3b3b3b;
}
加黑部分多了一個冒號。