#main-search {
    display: -webkit-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex;
    height: 48px;
}

#main-search form#search-block-form {
    overflow: hidden;
    max-width: 0;
    transition: max-width 0.6s ease-in-out;
    padding-left: 5px;
    margin: auto 0;
}

#main-search form#search-block-form.is-open {
    max-width: 200px;
}