body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.5;
  max-width: 800px;
  margin: 40px auto;
  padding: 0 20px;
  background-color: #fff;
  color: #000;
  transition: background-color 0.3s, color 0.3s;
}

body.dark-mode {
  background-color: #1a1a1a;
  color: #fff;
}

#qrcode {
  width: 256px;
  height: 256px;
  margin: 20px 0;
  border: 1px solid #ccc;
  transition: border-color 0.3s;
}

body.dark-mode #qrcode {
  border-color: #555;
}

input[type="text"] {
  width: 70%;
  padding: 8px;
  border: 1px solid #ccc;
  font-size: 14px;
  background-color: #fff;
  color: #000;
  transition: border-color 0.3s, background-color 0.3s, color 0.3s;
}

body.dark-mode input[type="text"] {
  border-color: #555;
  background-color: #2a2a2a;
  color: #fff;
}

select {
  padding: 8px;
  border: 1px solid #ccc;
  font-size: 14px;
  background-color: #fff;
  color: #000;
  transition: border-color 0.3s, background-color 0.3s, color 0.3s;
}

body.dark-mode select {
  border-color: #555;
  background-color: #2a2a2a;
  color: #fff;
}

button {
  margin-right: 10px;
  padding: 6px 12px;
  background: none;
  color: #000;
  border: 1px solid #000;
  cursor: pointer;
  font-size: 14px;
  transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}

body.dark-mode button {
  color: #fff;
  border-color: #fff;
}

button:hover {
  background-color: #f5f5f5;
}

body.dark-mode button:hover {
  background-color: #333;
}

hr {
  border: none;
  border-top: 1px solid #ccc;
  margin: 20px 0;
  transition: border-color 0.3s;
}

body.dark-mode hr {
  border-color: #555;
}

.dark-mode-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  padding: 8px 12px;
  border: 1px solid #000;
  background: none;
  cursor: pointer;
  font-size: 12px;
  transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}

body.dark-mode .dark-mode-toggle {
  color: #fff;
  border-color: #fff;
}

.dark-mode-toggle:hover {
  background-color: #f5f5f5;
}

body.dark-mode .dark-mode-toggle:hover {
  background-color: #333;
}