* {
  font-family: arial;
}

h2 {
  text-align: center;
}
/* SELECTS MULTIPLE ELEMENTS BY SEPARATING WITH COMMA */
p, button{
  /*color: red;*/
}

/* SELECTS ALL INSIDE OF DESCENDANT */
#outerDiv p {
  color: blue;
}

/* SELECTS ALL INSIDE PARENT (DIRECT DESCENDANT) */
#innerDiv > p {
  color:green;
}
/* SELECTS ALL ELEMENTS PLACED IMMEDIATELY AFTER AN ELEMENT */
h3 + p {
  color: blue;
  text-decoration:underline;
}
/* SELECTS ALL ELEMENTS PLACED IMMEDIATELY BEFORE AN ELEMENT */
p ~ h4 {
  color: orangered;
}