1. 效果图
2. 代码
<!DOCTYPE html><html><head><meta charset="UTF-8"><title>Title</title><style>/* 两边向中间渐变 */.center-to-sides {position: relative;margin: 75px 0;width: 100%;height: 1px;}.center-to-sides:before {content: "";position: absolute;background-image: linear-gradient(to right, #ff0000, transparent);left: 10%;right: 50%;height: 1px;}.center-to-sides:after {content: "";position: absolute;background-image: linear-gradient(to left, #ff0000, transparent);left: 50%;right: 10%;height: 1px;}/* 中间向两边渐变 */.sides-to-center {position: relative;margin: 75px 0;width: 100%;height: 1px;}.sides-to-center:before {content: "";position: absolute;background-image: linear-gradient(to left, #ff0000, transparent);left: 10%;right: 50%;height: 1px;}.sides-to-center:after {content: "";position: absolute;background-image: linear-gradient(to right, #ff0000, transparent);left: 50%;right: 10%;height: 1px;}</style></head><body><div class="center-to-sides"></div><div class="sides-to-center"></div></body></html>
