1.信封边框的实现
1.1 使用背景渐变
<!DOCTYPE html><html><head><meta charset="UTF-8"><title></title><style type="text/css">.uu {width: 200px;height: 70px;padding:1em;border: 1em solid transparent;background: linear-gradient(white,white) padding-box,repeating-linear-gradient(-45deg, red 0, red 12.5%, transparent 0, transparent 25%, #58a 0, #58a 37.5%, transparent 0, transparent 50%) 0/5em 5em; }</style></head><body><div class="uu"></div></body>
</html>
1.2 使用边框图片
<!DOCTYPE html><html><head><meta charset="UTF-8"><title></title><style type="text/css">.uu {width: 200px;height: 70px;padding: 1em;border: 1em solid transparent;background:linear-gradient(white,white) padding-box,repeating-linear-gradient(-45deg, red 0, red 12.5%, transparent 0, transparent 25%, #58a 0, #58a 37.5%, transparent 0, transparent 50%) 0/5em 5em;}</style></head><body><div class="uu"></div></body>
</html>
2.内凹圆角(优惠券)
2.1 使用伪类
<div class="main"></div>
<style>
.main {position: relative;width: 200px;height: 40px;margin: 0 5px;background: -webkit-linear-gradient(left, #F6327C, #DF3DF0);background: linear-gradient(to right, #F6327C, #DF3DF0);
}
.main::before {position: absolute;content: "";display: block;position: absolute;top: 0;left: -5px;width: 5px;height: 40px;border-radius: 2px 0 0 2px;background:-webkit-radial-gradient(10px at left,transparent 50%,#F6327C 50%);background: radial-gradient(10px at left,transparent 50%,#F6327C 50%);
}
.main::after {position: absolute;content: "";display: block;position: absolute;top: 0;right: -5px;width: 5px;height: 40px;border-radius: 0 2px 2px 0;background: -webkit-radial-gradient(10px at right,transparent 50%,#F6327C 50%);background: radial-gradient(10px at right,transparent 50%,#F6327C 50%);
}
</style>