body {background-image:url('https://s1.ax1x.com/2023/06/20/pC8E3m4.jpg');
  background-repeat:repeat-x;
  background-attachment:fixed;
}
a:link {text-decoration:none;}    /* 未访问链接 */
a:visited {text-decoration:none;text-decoration:none;} /* 已访问链接 */
a:hover {text-decoration:underline;}   /* 鼠标移动到链接上 */
a:active {text-decoration:underline;}  /* 鼠标点击时 */