@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;700&display=swap');

* {
    box-sizing: border-box;
}

body {
    font-family: 'Roboto' sans-serif;
    background: #373B44;  /* fallback for old browsers */
    background: -webkit-linear-gradient(to bottomt, #4286f4, #373B44);  /* Chrome 10-25, Safari 5.1-6 */
    background: linear-gradient(to bottom, #4286f4, #373B44); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    overflow: hidden;
    margin: 0;
}

.search {
    position: relative;
    height: 50px;
}

.search .input {
    background-color: #fff;
    border: 0;
    font-size: 18px;
    padding: 15px;
    height: 50px;
    width: 50px;
    transition: width 0.3s ease;
}

.btn {
    background-color: #fff;
    border: 0;
    cursor: pointer;
    font-size: 24px;
    position: absolute;
    top: 0;
    left: 0;
    height: 50px;
    width: 50px;
    transition: transform 0.3s ease;
}

.btn:focus, 
.input:focus {
    outline: none;
}

.search.active .input {
    width: 200px;
}

.search.active .btn {
    transform: translateX(198px);
}