hehe/user/themes/hehe/scss/template/_header.scss

header{
  position: fixed;
  width: 100%;
  height: 35px;
  top: 0;
  padding: 0 20px;
  display: flex;
  justify-content: space-between;
  background-color: white;
  border-bottom: 2px solid rgb(0,0,0);
  h1{
    margin: auto 0;
  }
  nav{
    margin: auto 0;
  }
  ul{
    display: flex;
    li{
      margin: 0 35px;
    }
  }
  ul.tags{
    display: none;
  }
  ul.visible{
    display: flex;
  }
}