.header {
  position: fixed;
  top: 0;
  width: 100%;
  height: 18px;
  background-color: #33ff00;
  padding: 10px 10px;
  display: flex;
  justify-content: space-between;
  text-align: center;
  align-items: center;
  z-index: 999;
}
.header a {
  font-family: 'roboto';
  color: #000000;
  font-weight:400 ;
  text-decoration: none;
  font-size: 18px;
  margin: 0 80px;
  transition: all 0.1s ease-in-out;

}
.header a:hover {
  font-family: 'roboto';
  font-weight:1000;
  color: #ffffff;
  text-decoration: none;
  font-size: 18px;
  margin: 0 80px;
}
/* ↑抬头设置 */