div{
    width: 100%;
    height: 100px;
    background-color: orange;
    margin: 0 auto 20px auto;
    border: 2px solid black;
    box-sizing: border-box;
}
.d1, .d2, .d3{
    animation-name: taille;
    animation-duration: 5s;
}
.d1{
    animation-timing-function: linear;
}
.d2{
    animation-timing-function: ease-in;
}
.d3{
    animation-timing-function: ease-out;
}
@keyframes taille{
    from{width: 100%;}
    50%{width: 50%;}
    to{width: 100%;}
}