body {
  margin: 0;
  font-family: sans-serif;
  background-color: #ffffff;
  color: #000000;
  transition: all 0.3s ease;
}
body.dark-mode {
  background-color: #121212;
  color: #ffffff;
}
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
  background: #000;
  color: white;
}
nav a {
  margin: 0 0.5rem;
  color: white;
  text-decoration: none;
}
nav button {
  margin-left: 1rem;
}
.logo {
  height: 60px;
}
section {
  padding: 2rem;
}
form input, form textarea {
  display: block;
  margin: 0.5rem 0;
  width: 100%;
  padding: 0.5rem;
}
form button {
  padding: 0.5rem 1rem;
}
footer {
  text-align: center;
  padding: 1rem;
  background-color: #222;
  color: #fff;
}