<html><head><style>#grad1 { height: 55px; background-color: red; /* 针对不支持渐变的浏览器 */ background-image: linear-gradient(to right, red, orange, yellow, green, blue, indigo, violet);}</style></head><body><div id="grad1" style="text-align:center;margin:auto;color:#888888;font-size:40px;font-weight:bold">彩虹背景</div></body></html>