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.

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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
}