/* 全局样式，后续可扩展 */
* { box-sizing: border-box; user-select: none; }
body { margin: 0; min-height: 100vh; }
.btn { cursor: pointer; border: none; font-family: inherit; }
.btn:hover { opacity: 0.9; }
input:focus { outline: none; border-color: #e67e22; }