:root {
  --bg-color: #ffffff;
  --text-color: #333333;
  --button-bg: #eeeeee;
  --button-text: #333333;
  --transition-speed: 0.3s;
}

body.dark-mode {
  --bg-color: #1a1a1a;
  --text-color: #f5f5f5;
  --button-bg: #333333;
  --button-text: #ffffff;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  transition: background-color var(--transition-speed), color var(--transition-speed);
  font-family: system-ui, -apple-system, sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100vh;
  margin: 0;
}

.theme-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  padding: 10px 20px;
  cursor: pointer;
  border: none;
  border-radius: 20px;
  background-color: var(--button-bg);
  color: var(--button-text);
  font-weight: bold;
  box-shadow: 0 2px 5px rgba(0,0,0,0.2);
  transition: transform 0.2s;
}

.theme-toggle:active {
  transform: scale(0.95);
}