/* Classes */
.firstparagraph, .secondparagraph, .thirdparagraph{
  background-color: yellow;
}

.secondparagraph {
  
font-size: 24px;
}

.myfontsize {
  font-size: 24px;
}

/* IDs */
#firstdiv {
  color: blue;
  font-size: 36px;
}

#seconddiv {
  background-color: red;
  font-weight: bold;
}