Html CSS边框呈现优先级

我有一个问题，Firefox和IE无论我做什么都拒绝渲染图像后面的边框，而Chrome和Opera做得很好。我已经将包含箭头的div移到了所有地方，甚至尝试用z-index强制它，但它不会移动。有什么建议吗

Chrome/Opera和IE/Firefox：

我在这里有一个JSFIDLE设置：

CSS:

---

您已将

位置：static

用于

标题

标记。使用

position:relative

，它将在ff和IE11中工作

html {
  height: 100%;
  background: #eee;
}

body {
  background: url(../img/background.jpg);
  background-repeat: no-repeat;
  background-size: cover;
  margin: 0px;
  height: 100%;
  overflow: hidden;
  background-position: center;
  font-family: Helvetica;
}

body.welcome {
  background: url(../img/welcome_background.jpg);
  background-size: cover;
  background-position: center;
}

p {
  margin: 0px;
}

::-webkit-scrollbar {
  width: 1px;
}

.wrapper {
  overflow-y: scroll;
  height: calc(100% - 90px);
}

header {
  position: static;
  top: 0;
  height: 60px;
}
header .logo {
  float: left;
  width: 256px;
}
header .logo .container {
  padding: 0 0 0 128px;
  height: 60px;
  background: white;
}
header .logo .container img {
  margin: 13px 0 0 0;
  width: 63px;
  height: 66px;
  filter: hue-rotate(0deg);
  -webkit-filter: hue-rotate(0deg);
  -moz-filter: hue-rotate(0deg);
  -o-filter: hue-rotate(0deg);
  -ms-filter: hue-rotate(0deg);
}
header .menu {
  float: left;
  background: white;
  width: calc(100% - 256px);
  height: 100%;
}
header .menu nav {
  float: left;
}
header .menu nav ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
}
header .menu nav ul li {
  float: left;
  width: 128px;
  line-height: 57px;
  letter-spacing: -2px;
  text-align: center;
  font-size: 19px;
  text-transform: uppercase;
  color: #8a8a8a;
  border-top: 3px solid white;
}
header .menu nav ul li.active {
  color: #f05555;
  border-top: 3px solid #f05555;
}
header .menu .container {
  float: right;
  padding-right: 128px;
}

.before {
  content: "";
  position: absolute;
  top: 60px;
  left: 130px;
  border-top: 23px solid white;
  border-left: 28px solid transparent;
  border-right: 28px solid transparent;
}

div.content {
  width: 100%;
  height: calc(100% - 90px);
}
div.content .menu {
  height: 50px;
}
div.content .container {
  overflow-y: scroll;
  height: 100%;
  margin: 0 128px 0 128px;
  width: calc(100% - 256px);
  background: white;
}

footer {
  position: static;
  bottom: 0;
  height: 30px;
  background: white;
  padding: 0 0 0 128px;
  line-height: 30px;
  font-size: 10px;
  color: #8a8a8a;
}