body {
  background: #181818;
  color: #f5f5f5;
}
a { color: #4fc3f7; }
button, input, select {
  background: #222;
  color: #f5f5f5;
  border: 1px solid #444;
}
header, nav, footer {
  background: #222;
}
hr { border-color: #444; }
/* 可继续补充全局和常用元素样式 */