/* Element name selector: styles applied to the body element */
body {
  background-color: #f9f9f9;
  font-family: Arial, sans-serif;
  margin: 20px;
}

/* Class name selector: styles applied to elements with the class 'highlight' */
.highlight {
  color: #3333cc;
  font-weight: bold;
}

/* Id selector: styles applied to the element with the id 'mainHeader' */
#mainHeader {
  color: #cc3333;
  text-align: center;
}