#one.two { color:blue; }

img  {
  float: left;
}

#para1 {
  text-align: center;
  color: red;
}

<style>
.intro {
  background-color: red;
}
</style>


body {
  background-image: ("background.jpg") ;
}

header, footer {
  background-color: grey;
  border: solid 7px blue;
  font-family: courier, serif;
}

.nav {
  background-color: yellow; 
  list-style-type: none;
  text-align: center;
  margin: 0;
  padding: 0;
}

.nav li {
  display: inline-block;
  font-size: 20px;
  padding: 20px;
}

}

.nav li {
  display: inline-block;
  font-size: 20px;
  padding: 20px;
}