*{
    box-sizing: border-box;
}

body{
    display: flex;
    flex-direction: column;
    align-items: center;
    background-color: azure;
}
.container{
    padding-bottom: 20px;
}
.challenges{
    padding-top: 20px;
    display: grid;
    grid-template-columns: 1fr;
    overflow: hidden;
}
@media (min-width: 600px){
.challenges{
    padding-top: 20px;
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 1fr;
}}


.box{
    background-color:teal;
    color: aliceblue;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 300px;
    height:150px;
    margin: 20px;
    border-radius: 10px ;
    box-shadow: 2px 4px 5px rgb(0, 0,0, 0.3) ;
    transform: translateX(500%);
    transition: transform 0.5s ease;

}
.box:nth-of-type(even){
    transform: translateX(-500%);
}
.box.show{
    transform: translateX(0);
}

.box h2{
    font-size: 50px;
}


a {
    color: #fff;
    text-transform: uppercase;
    text-decoration: none;
    font-size: 16px;
    display: inline-block;
    position: relative;
  }
  a:after {    
    background: none repeat scroll 0 0 transparent;
    bottom: 0;
    content: "";
    display: block;
    height: 2px;
    left: 50%;
    position: absolute;
    background: #fff;
    transition: width 0.3s ease 0s, left 0.3s ease 0s;
    width: 0;
  }
  a:hover:after { 
    width: 100%; 
    left: 0; 
  }