css 此css允许您从框元素创建一个箭头，以便为其提供聊天气泡效果。

Posted 2021-05-13

.dropdown-menu {
    top:90px;
    left:30px;
    padding:10px;
    background-color: #ebebeb;
    border: 1px solid #c4c4c4;
    border-radius: 5px;
}
.dropdown-menu:before {
    content: ' ';
    height:0;
    position:absolute;
    width:0;
    border: 12px solid transparent;
    border-bottom-color: #c4c4c4;
    left: 20px;
    top:-25px;
}
.dropdown-menu:after {
    content: ' ';
    height:0;
    position:absolute;
    width:0;
    border: 12px solid transparent;
    border-bottom-color: #ebebeb;
    left: 20px;
    top:-24px;
}