body, html {
  height: 100%;
  margin: 0;
  font-family: 'Roboto', Arial, sans-serif; /* 更换字体 */
  display: flex;
  justify-content: center;
  align-items: center;
  background: linear-gradient(135deg, #f5f7fa, #c3cfe2); /* 渐变背景 */
  color: #333;
}

.container {
  text-align: center;
  background: white;
  padding: 2rem; /* 增加内边距 */
  border-radius: 12px; /* 圆角更大 */
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.15);
  width: 500px;
  max-width: 90%;
  height: auto; /* 自动高度 */
}

.captcha-image {
  max-width: 100%;
  height: auto;
  margin-bottom: 1.5rem; /* 增加间距 */
}

.input-group input {
  width: 100%;
  padding: 15px 20px; /* 增加内边距 */
  border: 1px solid #e0e0e0;
  border-radius: 8px;
  font-size: 18px; /* 字体大小增加 */
  transition: all 0.2s ease-in-out; /* 添加过渡效果 */
  height: 50px; /* 设置固定高度 */
}

.input-group input:focus {
  border-color: #007bff;
  outline: none;
  box-shadow: 0 0 8px rgba(0, 123, 255, 0.4);
}

.submit-button {
  margin-top: 20px; /* 增加与输入框之间的间距 */
  padding: 15px 30px; /* 增加内边距 */
  background: linear-gradient(135deg, #007bff, #0056b3);
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-size: 18px; /* 字体大小增加 */
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  transition: all 0.2s ease-in-out; /* 添加过渡效果 */
}

.submit-button:hover,
.submit-button:focus {
  background: linear-gradient(135deg, #0056b3, #003d80);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}
.custom-message-box {
  font-family: Arial, sans-serif;
  font-size: 14px;
}