元素无法垂直居中？

Question

元素无法垂直居中

Answer 1

.side-tool a i {  line-height:40px;  /*vertical-align: middle;*/}

Answer 2

.side-tool{  display: flex;  flex-direction: column;  justify-content: center;  align-items: center;  position:  fixed;  right: 1%;  bottom: 5%;  width: 40px;  border: 1px solid #eee;  background-color: white;  text-align: center;  font-size: 24px;  z-index: 1040;}