header{
  display: flex;
  position: fixed;
  top:0;
  left:0;
  background-color: white;
  width: 100%;
  height: 70px;
}
main{
  margin-top: 70px;
}
nav{
    width: 100%;
}
nav ul{
  display: flex;
  justify-content: space-around;
  list-style-type: none;
  line-height: 60px;
}
.one{
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
}
img{
  width: 100%;
}
.box01,.box02,.box03{
  width: 400px;
}