废话不多说，直接上代码，希望能帮到有需要的小伙伴
①：遮罩
position: fixed;
background: rgba(0, 0, 0, .4);
top: 0;
left: 0;
right: 0;
bottom: 0;
z-index: 99;
width: 100%;
height: 100%;
②：三角（下面三角的代码按照下图上右下左的顺序排列）
width: 0;
height: 0;
border-width: 8px;
border-style: solid;
border-color: transparent transparent #000 transparent;
width: 0;
height: 0;
border-width: 8px;
border-style: solid;
border-color: #000 transparent transparent transparent;
width: 0;
height: 0;
border-width: 8px;
border-style: solid;
border-color: transparent #000 transparent transparent;
width: 0;
height: 0;
border-width: 8px;
border-style: solid;
border-color: transparent #000 transparent transparent;
③：圆
display: inline-block;
width: 10px;
height: 10px;
border-radius: 50%;
background-color: #f6ad03;
④：图标
width: 24px;
box-shadow: 0 10px 0 2px #999, 0 20px 0 2px #999, 0 30px 0 2px #999;
⑤：超出隐藏
width: 180px；
overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap;
6：垂直居中
position: fixed;
top: 0;
right: 0;
bottom: 0;
left: 0;
margin: auto;
注：针对元素有固定宽高的情况
position: fixed;
top: 50%;
left: 50%;
z-index: 999;
transform: translate(-50%,-50%);
注：针对元素无固定宽高的情况