.jiaru {
  min-width: 130px;
  height: 40px;
  color: #fff;
  padding: 5px 10px;
  font-weight: bold;
  cursor: pointer;
  transition: all 0.3s ease;
  position: relative;
  display: inline-block;
  outline: none;
  border-radius: 20px;
  border: 2px solid #495057;
  background: #495057;
}
.jiaru:hover {
  background: #fff;
  color: #495057
}
@media screen and (max-width: 768px) {
  .yidongduan {
  min-width: 130px;
  height: 40px;
  color: #fff;
  padding: 5px 10px;
  font-weight: bold;
  cursor: pointer;
  transition: all 0.3s ease;
  position: relative;
  display: inline-block;
  outline: none;
  border-radius: 5px;
  z-index: 0;
  background: #fff;
  overflow: hidden;
  border: 2px solid #495057;
    
  color: #495057;
}
.yidongduan:hover {
   color: #fff;
}
.yidongduan:hover:after {
  width: 100%;
}
.yidongduan:after {
  content: "";
  position: absolute;
  z-index: -1;
  transition: all 0.3s ease;
  left: 0;
  top: 0;
  width: 0;
  height: 100%;
  background: #495057;
}
}