Set the font-weight property of the p element to bold.

<html>
<head>
  <style>
p{
font-weight: bold;}
</style>
</head>
<body>
  <h1>Cool Things To Own</h1>
  <p>A time machine</p>
  <p>A hydraulic press</p>
</body>
</html>]]>

Make sure to assemble p first, then font-weight, and finally bold.