body, html {
    height: 100%;
    margin: 0;
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center; /* 垂直居中 */
    text-align: center;
}

.loader {
    border: 8px solid #f3f3f3; /* 背景圈颜色 */
    border-top: 8px solid #3498db; /* 前景圈颜色 */
    border-radius: 50%;
    width: 80px;
    height: 80px;
    animation: spin 2s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Optional: Center content vertically in the body */
.content {
    display: flex;
    flex-direction: column; /* 垂直排列内容 */
    align-items: center; /* 水平居中对齐 */
    justify-content: center; /* 垂直居中对齐 */
}