设置纯css箭头到透明或图像背景菜单？

Question

我正在尝试将纯css箭头应用于我的水平和垂直菜单的SELECTED链接,但似乎无法弄清楚我想要的结果.stackoverflow中有一些类似的解决方案但它并没有解决我的问题.

UL有边界,这就是问题所在......但我不应该删除UL边界.

骗子在这里

<li class="selected"><a href="#">Arrow please</a></li>

ul.hor {
  border-bottom: 3px solid blue;
}
ul li {
  display: inline-block;
  position: relative;
}
ul li a {
  display: block;
  padding: 10px 15px;
}
ul li.selected a {
  color: green;
}
ul li.selected:after {
  content: "";
  width: 12px;
  height: 12px;
  position: absolute;
  background: #fff;
  border-top: 3px solid blue;
  border-right: 3px solid blue;
}
ul.hor li.selected:after {
  left: 0;
  right: 0;
  bottom: -8px;
  margin: 0 auto;
  -moz-transform: rotate(315deg);
  -webkit-transform: rotate(315deg);
  -ms-transform: rotate(315deg);
}
ul.ver li.selected:after {
  right: -8px;
  top: 50%;
  margin-top: -6px;
  -moz-transform: rotate(225deg);
  -webkit-transform: rotate(225deg);
  -ms-transform: rotate(225deg);
}
ul.ver {
  width: 200px;
  border-right: 3px solid blue;
}
ul.ver li {
  display: block;
}
ul.ver li a {
  display: block;
  padding: 10px 15px;
}
body {
  width: 90%;
  margin: 20px auto;
  background: rgb(229, 180, 230);
  background: -moz-linear-gradient(30deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
  background: -webkit-linear-gradient(30deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
  background: -o-linear-gradient(30deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
  background: -ms-linear-gradient(30deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
  background: linear-gradient(120deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
}

<ul class="hor">
  <li><a href="#">Lorem</a></li>
  <li><a href="#">Ipsum</a></li>
  <li class="selected"><a href="#">Sit amet</a></li>
  <li><a href="#">Consectetur</a></li>
</ul>
<br>
<ul class="ver">
  <li><a href="#">Lorem</a></li>
  <li><a href="#">Ipsum</a></li>
  <li class="selected"><a href="#">Sit amet</a></li>
  <li><a href="#">Consectetur</a></li>
</ul>

Answer 1

这个更容易定位,并有一个完美的三角形.我们仍在使用变换旋转但不需要变换偏斜.无需计算宽度. 小提琴这里.

ul {
    overflow: hidden;
}
li {    
    display:inline-block;position: relative;
}
ul li a {
  display: block;padding:20px 15px;
}
ul li.selected a {
  color: green;
}
ul.hor li.selected:before,
ul.hor li.selected:after {
   content: "";
   bottom: 0;
   position: absolute;
   border-bottom:3px solid blue;
   width:9999px;
   margin:0 10px;left:50%;
}
ul.hor li.selected:after {
    left:auto;right:50%;
}
/*vertical menu starts*/
ul.ver {
  width: 200px;
}
ul.ver li {
  display: block;
}
ul.ver li a {
  padding:10px 15px;
}
ul.ver li.selected:before,
ul.ver li.selected:after {
   content: "";
   position: absolute;
   top:50%;
   right: 0;
   border-right:3px solid blue;
   height:9999px;
   margin:10px 0
}
ul.ver li.selected:after {
    top:auto;bottom:50%;
}

/*arrow starts*/
ul li.selected a:after {
    content: "";
    width: 15px;
    height: 15px;
    position: absolute;
    border: solid blue;
    border-width: 3px 3px 0 0;  
}

ul.hor li.selected a:after {
    top:100%;
    left: 0;
    right: 0;
    margin: -10px auto 0; 
    -moz-transform: rotate(315deg);
    -webkit-transform: rotate(315deg);
    -ms-transform: rotate(315deg);
}
ul.ver li.selected a:after {
    left:100%;
    margin-left:-10px;
    -moz-transform:rotate(225deg);
    -webkit-transform:rotate(225deg);
    -ms-transform:rotate(225deg);
}
body {
    width:90%;margin:20px auto;
    background: rgb(229, 180, 230);
background: -moz-linear-gradient(30deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
background: -webkit-linear-gradient(30deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
background: -o-linear-gradient(30deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
background: -ms-linear-gradient(30deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
background: linear-gradient(120deg, rgb(229, 180, 230) 30%, rgb(90, 140, 250) 70%);
}

<ul class="hor">
	    <li><a href="#">Lorem</a></li>
	    <li class="selected"><a href="#">Ipsum</a></li>
	    <li><a href="#">Sit amet</a></li>
	    <li><a href="#">Consectetur</a></li>
	</ul>
<br>
	<ul class="ver">
	    <li class="selected"><a href="#">Lorem</a></li>
	    <li><a href="#">Ipsum</a></li>
	    <li><a href="#">Sit amet</a></li>
	    <li><a href="#">Consectetur</a></li>
	</ul>