css
/* style.css */

body {
  font-family: 'Helvetica', 'Arial', 'sans-serif';
  margin: 0;
  padding: 0;
  background-color: #f5f5f5;
  color: #000;
  width: 800px;
  height: 600px;
  margin: 0 auto;
  box-shadow: 0 0 10px rgba(0,0,0,0.5);
}

body:root {
  background-color: #333;
  color: #fff;
  box-shadow: 0 0 10px rgba(0,0,0,0.5);
}

h1 {
  font-size: 24px;
  font-weight: bold;
  color: #fff;
  text-align: center;
  margin-bottom: 20px;
}

h2 {
  font-size: 18px;
  font-weight: bold;
  color: #000;
  text-align: center;
  margin-bottom: 20px;
}

p {
  font-size: 14px;
  margin-bottom: 20px;
}

a {
  text-decoration: none;
  color: #333;
  text-align: center;
  text-transform: uppercase;
  border-radius: 10px;
  background-color: #f5f5f5;
  padding: 4px 10px;
  border: 1px solid #000;
  box-shadow: 0 0 5px rgba(0,0,0,0.5);
  transition: background-color 0.2s ease;
  text-align: center;
}

a:hover {
  background-color: #ccc;
  box-shadow: 0 0 10px rgba(0,0,0,0.5);
}

a:active {
  background-color: #aaa;
  box-shadow: 0 0 15px rgba(0,0,0,0.5);
}