/* 基础布局 */
body {
  font-family: "Microsoft YaHei", sans-serif;
  background: #f2f6fc;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  min-height: 100vh;
}

.container {
  background: #fff;
  margin: 20px auto;
  padding: 20px;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  width: 95%;
  max-width: 500px;
}

h2 {
  text-align: center;
  color: #333;
  margin-bottom: 20px;
}

.form-group {
  margin-bottom: 20px;
}

label {
  display: block;
  margin-bottom: 6px;
  font-weight: bold;
  color: #555;
}

input[type="text"] {
  width: 100%;
  padding: 14px;
  font-size: 16px;
  border-radius: 8px;
  border: 1px solid #ddd;
  box-sizing: border-box;
  transition: border 0.2s;
}

input[type="text"]:focus {
  border-color: #409eff;
  outline: none;
}

.btn {
  width: 100%;
  padding: 16px;
  background: #409eff;
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 18px;
  cursor: pointer;
  transition: background 0.2s;
}

.btn:hover {
  background: #66b1ff;
}

.result {
  margin-top: 20px;
  text-align: center;
  font-weight: bold;
  font-size: 16px;
}

/* 响应式设计 */
@media (max-width: 400px) {
  .container { padding: 15px; }
  input[type="text"] { padding: 12px; font-size: 14px; }
  .btn { padding: 14px; font-size: 16px; }
}