body {
  margin: 0;
  font-family: 'Segoe UI', sans-serif;
  background-color: #0d0d0d;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

.app {
  width: 90%;
  max-width: 500px;
  text-align: center;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

button#darkToggle {
  background: none;
  border: none;
  font-size: 24px;
  cursor: pointer;
  color: white;
}

.loader {
  border: 6px solid #333;
  border-top: 6px solid #00ffcc;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  animation: spin 1s linear infinite;
  margin: 30px auto;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.wallet-card {
  background: #1f1f1f;
  border: 1px solid #333;
  padding: 16px;
  border-radius: 10px;
  margin-top: 20px;
  animation: fadeIn 0.5s ease-in-out forwards;
}

@keyframes fadeIn {
  from {opacity: 0; transform: translateY(20px);}
  to {opacity: 1; transform: translateY(0);}
}

.dark-mode {
  background-color: #f4f4f4;
  color: #000;
}

.dark-mode .wallet-card {
  background-color: #fff;
  color: #000;
}