style.css

body{
    background: #ecf0f1;
    font-family: 'source sans pro';
    font-weight: 400;
}
h1{
    font-size: 35px;
    color: #2c97de;
    text-align: center;
}
h2{
    font-size: 35px;
    color: #2c97de;
    text-align: center;
}
.accordionMenu{
    width: 500px;
    margin: 0 auto;
}
.accordionMenu input[type=radio]{
    display: none;
}
.accordionMenu label{
    background: #2c97de;
    font-size: 18px;
    color: #fff;
    position: relative;
    cursor: pointer;
    display: block;
    height: 50px;
    line-height: 47px;
    padding: 0 25px 0 10px;
    border-bottom: 1px solid #e6e6e6;
}
.accordionMenu label::after{
    display: block;
    content: "";
   border-style: solid;
    border-width: 5px 0 5px 10px;
    border-color: transparent transparent transparent #ffffff;
    position: absolute;
    width: 0;
    height: 0;
    right: 10px;
    top: 20px;
    z-index: 10;
    -moz-transition: all 0.3s ease-in-out;
    -ms-transition:all 0.3s ease-in-out;
    -o-transition: all 0.3s ease-in-out;
    -webkit-transition: all 0.3s ease-in-out;
    transition: all 0.3s ease-in-out;
}
.accordionMenu .content{
    max-height: 0;
    height: 0;
    overflow: hidden;
   -moz-transition: all 2s ease-in-out;
    -o-transition: all 2s ease-in-out;
    -webkit-transition: all 2s ease-in-out;
    transition: all 2s ease-in-out;
}
.accordionMenu .content .inner{
    font-size: 1.2rem;
    color: #2c97de;
    line-height: 1.5;
    background: white;
    padding: 20px 10px;
}
.accordionMenu input[type=radio]:checked + label:after{
    -moz-transform: rotate(90deg);
     -ms-transform: rotate(90deg);
     -o-transform: rotate(90deg);
     -webkit-transform: rotate(90deg);
     transform: rotate(90deg);
 }
  
 .accordionMenu input[type=radio]:checked + label + .content{
     max-height: 2000px;
     height: auto;
 }