css知识汇总

<style type="text/css">
table{
border-collapse:collapse;
}
table, td, th{
border:1px solid black;
}
</style>

.nav-item:after {
content: '';
position: absolute;
right: 16px;
top: 5px;
width: 5px;
height: 5px;
border: 1px solid #9b9b9b;
border-width: 0 1px 1px 0;
transform: rotate(45deg);
-webkit-transform: rotate(45deg);
-moz-transform: rotate(45deg);
}