*{
  list-style: none;
  text-decoration: none;
  border-collapse: collapse;
  padding: 0;
  margin: 0;
  color: black;
}

.intro_bg{
  background-image:url("image/intro.png") ;
  width: 1920px;
  height: 520px;
  margin: auto;
  }

.header{
  display: flex ;
  width: 935px ;
  height: 87px ;
  margin: auto ;
  
}

.nav{
  display: flex;
  justify-content: flex-end;
  width: 935px;
  height: 87px;
  line-height: 87px;
  font-weight: bold;
  font-size: 22px;
}

.nav > li{
  margin-left: 70px;
}

.nav > li > span{
  margin-left: 70px;
}

.second_bg{
  background-color: #ffe9e9;
  width: 1920px;
  height: 100vh;
  margin: -10px auto;
}

.portfolio{
  background-color: yellowgreen;
  font-size: 20px;
  font-weight: bolder;
  width: 300px;
  height: 50px;
  border-radius: 10px;
  align-content: center;
  margin: auto;
  color: black;
  position: relative;
  top: 050px;
}


.portfolio > span{
  background-color: yellowgreen;
  padding: 10px;
}