body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  text-align: center;
  background-color: #fff;
}
header {
  padding: 20px;
  background: #f5f5f5;
}
#logo {
  width: 150px;
  height: auto;
  margin: 0 auto 10px;
  display: block;
}
h1, h2 { margin: 10px 0; }
p { margin: 10px 20px; }
a.btn-primary, a.btn-secondary, a.btn-download, a.btn-pay {
  display: inline-block;
  margin: 10px;
  padding: 12px 20px;
  border-radius: 5px;
  text-decoration: none;
  color: #fff;
}
.btn-primary { background-color: #007BFF; }
.btn-secondary { background-color: #28a745; }
.btn-pay { background-color: #e53935; }
.btn-download { background-color: #6c63ff; }
form input, form label {
  display: block;
  margin: 10px auto;
  max-width: 90%;
  width: 300px;
  font-size: 1rem;
}
footer {
  background: #eee;
  padding: 15px;
  font-size: 0.9rem;
}