Div底部的中心三角形

Question

我试图在我的英雄的底部有一个三角形/箭头,但它没有响应,并且在移动设备上不能很好地工作,因为三角形漂浮到右边并且不再是绝对居中.

我怎么能一直将三角形放在div底部的绝对中心？

这里的示例代码:

http://jsfiddle.net/SxKr5/1/

HTML:

<div class="hero"></div>

CSS:

.hero {     
    position:relative;
    background-color:#e15915;
    height:320px !important;
    width:100% !important;


}


.hero:after,
.hero:after {
    z-index: -1;
    position: absolute;
    top: 98.1%;
    left: 70%;
    margin-left: -25%;
    content: '';
    width: 0;
    height: 0;
    border-top: solid 50px #e15915;
    border-left: solid 50px transparent;
    border-right: solid 50px transparent;
}

Answer 1

你就不能设置left到50%,然后都margin-left设置为-25px考虑到它的宽度:http://jsfiddle.net/9AbYc/

.hero:after {
    content:'';
    position: absolute;
    top: 100%;
    left: 50%;
    margin-left: -50px;
    width: 0;
    height: 0;
    border-top: solid 50px #e15915;
    border-left: solid 50px transparent;
    border-right: solid 50px transparent;
}

或者如果您需要可变宽度,您可以使用:http://jsfiddle.net/9AbYc/1/

.hero:after {
    content:'';
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    margin: 0 auto;
    width: 0;
    height: 0;
    border-top: solid 50px #e15915;
    border-left: solid 50px transparent;
    border-right: solid 50px transparent;
}

Answer 2

您可以使用以下css使元素中间对齐样式position: absolute:

.element {
  transform: translateX(-50%);
  position: absolute;
  left: 50%;
}

使用CSS只会left: 50%产生以下效果:

同时结合left: 50%与transform: translate(-50%)我们有以下几点:

.hero { 	
  background-color: #e15915;
  position: relative;
  height: 320px;
  width: 100%;
}


.hero:after {
  border-right: solid 50px transparent;
  border-left: solid 50px transparent;
  border-top: solid 50px #e15915;
  transform: translateX(-50%);
  position: absolute;
  z-index: -1;
  content: '';
  top: 100%;
  left: 50%;
  height: 0;
  width: 0;
}

<div class="hero">

</div>

Answer 3

检查一下:

http://jsfiddle.net/SxKr5/3/

.hero1
{
    width: 90%;
    height: 200px;
    margin: auto;
    background-color: #e15915;
}

.hero2
{
    width: 0px;
    height: 0px;
    border-style: solid;
    margin: auto;
    border-width: 90px 58px 0 58px;
    border-color: #e15915 transparent transparent transparent;
    line-height: 0px;
    _border-color: #e15915 #000000 #000000 #000000;
    _filter: progid:DXImageTransform.Microsoft.Chroma(color='#000000')
}