::after is not working in css code example

Example 1: css after not working

/*Add the property: content: ""; */ 

.myclass:{
  content: "";
  ...
}

Example 2: css before is not working

.chart ul:after{
  content: "";
  border:1px solid #f30;
}

Example 3: after element is blocking

.select:after {
    position:absolute;
    bottom:.15em;
    top:.15em;
    right:.5rem;
    content:'\2193';
    pointer-events: none;
}