:root {
  --background-color: #f0f2f5;
  --text-color: #333;
  --card-bg-color: #f9f9f9;
  --card-shadow-color: rgba(0,0,0,0.1);
  --button-bg-color: #5cb85c;
  --button-text-color: white;
}

[data-theme="dark"] {
  --background-color: #2c2c2c;
  --text-color: #f0f2f5;
  --card-bg-color: #3a3a3a;
  --card-shadow-color: rgba(255,255,255,0.1);
  --button-bg-color: #4CAF50;
  --button-text-color: white;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  background-color: var(--background-color);
  color: var(--text-color);
  transition: background-color 0.3s, color 0.3s;
}

.theme-switcher-container {
  position: absolute;
  top: 20px;
  right: 20px;
}

#theme-switcher {
  padding: 8px 16px;
  border-radius: 6px;
  border: 1px solid var(--text-color);
  background-color: var(--button-bg-color);
  color: var(--button-text-color);
  cursor: pointer;
  transition: background-color 0.3s, color 0.3s;
}

#theme-switcher:hover {
    opacity: 0.8;
}