Center Triangle at Bottom of Div

Question

I am trying to have a triangle/arrow at the bottom of my hero but it is not responsive and doesn't work on mobile very well as the triangle floats off to the right and is not absolutely centered anymore.

How could I keep the triangle positioned in the absolute center at the bottom of the div at all times?

Example code here:

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

Can't you just set left to 50% and then have margin-left set to -25px to account for it's width: 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; } 

or if you needed a variable width you could use: 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

You can use following css to make an element middle aligned styled with position: absolute:

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

With CSS having only left: 50% we will have following effect:

While combining left: 50% with transform: translate(-50%) we will have following:

.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>