h1{color:red;}
h2{color:blue;}
h3{color:red;}
p{text-decoration:underline;}
#obstacles{
  background-color: yellow;
  border: dashed black 2px;
  padding:2em;
  margin:2em;
}
li{
  color:green;
}
.bg-red{background-color: red;} 
.text-blue{color: blue;}