Css arrow Progress bar

Question

I\'m currently in the process of learning all about css, so I\'m trying to generate different shapes with different functionalities.

---

I am currently working on

Answer 1

You can animate just the width of the .prog element and set it to overlfow: hidden

.prog{
    width: 0%;
    height:100%;
    position: relative;
    overflow: hidden;
    transition: width 0.8s 
}
.arrow:hover .prog{
    width: 300px;
}
.arrow{  
    height:200px;
    margin:0 auto;
    width:300px;
    position:relative;
    margin-top:60px;
}
.arrow,.arrow:before,.arrow:after{
    z-index:1
}
.prog,.prog:before,.prog:after{
    z-index:2
}
.arrow:before, .prog:before,
.arrow:after, .prog:after{
    content:"";
    position:absolute;
}
.arrow:before, .prog:before{
    left: 200px;
    top: 0px;
    border-top: 100px solid transparent;
    border-bottom: 100px solid transparent;
}
.arrow:after, .prog:after{
    margin: 0 auto;
    height: 100px;
    width: 200px;
    top: 50px;
    left: 0
}
.arrow:before{
    border-left: 100px solid red
}
.arrow:after{
    background: red
}
.prog:before{
    border-left: 100px solid blue
}
.prog:after{
    background: blue
}

<div class="arrow">
    <div class="prog"></div>
</div>

Answer 2

Although this may only be suitable for block color backgrounds, I thought I'd add it here (as I was learning I found that 'cutting the arrow out' was also an option). I started with a rectangle and 'cut the corners out' to create this:

.arrow {
  height: 200px;
  width: 300px;
  background: rgb(169, 3, 41);
  background: -moz-linear-gradient(top, rgba(169, 3, 41, 1) 0%, rgba(143, 2, 34, 1) 44%, rgba(109, 0, 25, 1) 100%);
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, rgba(169, 3, 41, 1)), color-stop(44%, rgba(143, 2, 34, 1)), color-stop(100%, rgba(109, 0, 25, 1)));
  background: -webkit-linear-gradient(top, rgba(169, 3, 41, 1) 0%, rgba(143, 2, 34, 1) 44%, rgba(109, 0, 25, 1) 100%);
  background: -o-linear-gradient(top, rgba(169, 3, 41, 1) 0%, rgba(143, 2, 34, 1) 44%, rgba(109, 0, 25, 1) 100%);
  background: -ms-linear-gradient(top, rgba(169, 3, 41, 1) 0%, rgba(143, 2, 34, 1) 44%, rgba(109, 0, 25, 1) 100%);
  background: linear-gradient(to bottom, rgba(169, 3, 41, 1) 0%, rgba(143, 2, 34, 1) 44%, rgba(109, 0, 25, 1) 100%);
  filter: progid: DXImageTransform.Microsoft.gradient(startColorstr='#a90329', endColorstr='#6d0019', GradientType=0);
  position: relative;
  overflow: hidden;
  transition: all 0.8s;
}
.arrow:before {
  content: "";
  position: absolute;
  top: 0;
  width: 70%;
  height: calc(100% - 80px);
  border-top: 40px solid white;
  border-bottom: 40px solid white;
  z-index: 10;
}
.arrow:after {
  content: "";
  position: absolute;
  right: 0;
  border-top: 100px solid white;
  border-bottom: 100px solid white;
  border-left: 100px solid transparent;
  z-index: 10;
}
.perc {
  position: absolute;
  top: 0;
  width: 0%;
  height: 100%;
  background: rgb(30, 87, 153);
  background: -moz-linear-gradient(top, rgba(30, 87, 153, 1) 0%, rgba(41, 137, 216, 1) 50%, rgba(32, 124, 202, 1) 51%, rgba(125, 185, 232, 1) 100%);
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, rgba(30, 87, 153, 1)), color-stop(50%, rgba(41, 137, 216, 1)), color-stop(51%, rgba(32, 124, 202, 1)), color-stop(100%, rgba(125, 185, 232, 1)));
  background: -webkit-linear-gradient(top, rgba(30, 87, 153, 1) 0%, rgba(41, 137, 216, 1) 50%, rgba(32, 124, 202, 1) 51%, rgba(125, 185, 232, 1) 100%);
  background: -o-linear-gradient(top, rgba(30, 87, 153, 1) 0%, rgba(41, 137, 216, 1) 50%, rgba(32, 124, 202, 1) 51%, rgba(125, 185, 232, 1) 100%);
  background: -ms-linear-gradient(top, rgba(30, 87, 153, 1) 0%, rgba(41, 137, 216, 1) 50%, rgba(32, 124, 202, 1) 51%, rgba(125, 185, 232, 1) 100%);
  background: linear-gradient(to bottom, rgba(30, 87, 153, 1) 0%, rgba(41, 137, 216, 1) 50%, rgba(32, 124, 202, 1) 51%, rgba(125, 185, 232, 1) 100%);
  filter: progid: DXImageTransform.Microsoft.gradient(startColorstr='#1e5799', endColorstr='#7db9e8', GradientType=0);
  z-index: 5;
  transition: all 0.8s;
}
.arrow:hover .perc {
  width: 100%;
}

<div class="arrow">
  <div class="perc"></div>
</div>

---

Let's not forget those who prefer Jsfiddle's instead

---

It would also allow for a gradient colouring