body {
  font-family: 'Segoe UI', sans-serif;
  margin: 0;
  background: #f4f4f4;
  color: #333;
}

header {
  background: linear-gradient(to right, #0055a4, #ffffff, #ef4135);
  padding: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

nav a, nav button {
  margin-left: 20px;
  text-decoration: none;
  color: #fff;
  background: #333;
  padding: 10px 15px;
  border-radius: 5px;
  border: none;
  cursor: pointer;
}

section {
  padding: 40px;
}

.modal {
  display: none;
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: rgba(0,0,0,0.5);
}

.modal-content {
  background: white;
  padding: 30px;
  margin: 100px auto;
  width: 300px;
  border-radius: 10px;
}