HTML5弹出式全屏搜索框

参考：

https://wow.techbrood.com/fiddle/35740

CSS

* {
    margin: 0;
    padding: 0;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}
body {
    background: #263238;
    position: relative;
}
.close {
    position: absolute;
    color: #fff;
    top: 20px;
    right: 50px;
    font-size: 1.7em;
    cursor: pointer;
    display: none;
    z-index: 999;
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
    -webkit-transition: all 600ms cubic-bezier(0.68, -0.55, 0.265, 1.55);
    transition: all 600ms cubic-bezier(0.68, -0.55, 0.265, 1.55);
}
.close:hover {
    font-size: 2.4em;
    -webkit-transform: rotate(360deg);
    transform: rotate(360deg);
}
/*-------------- saerch section -----------*/

.search {
    position: fixed;
    top: 50%;
    left: 50%;
    -webkit-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
    border-radius: 1000px;
    width: 0;
    height: 0;
    background: #03a9f4;
    -webkit-transition: all .4s linear;
    transition: all .4s linear;
}
.search i {
    color: #03a9f4;
    font-size: 1.7em;
    cursor: pointer;
}
.search .input {
    position: absolute;
    top: 50%;
    left: 50%;
    -webkit-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
    width: 350px;
    height: 40px;
    background: transparent;
    border: none;
    outline: none;
    border-bottom: 3px solid #eee;
    color: #eee;
    font-size: 1.3em;
    display: none;
}
.search.open {
    height: 4000px;
    width: 4000px;
}

 

$(function() {
$('.fa-search').on('click', function() {
$('.search').addClass('open');
$('.close, .input').fadeIn(500);
});

$('.close').on('click', function() {
$('.search').removeClass('open');
$('.close, .input').fadeOut(500);
});
});

<link rel='stylesheet prefetch' href='https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css'>

<!----- close button ----->
<div class="close">
    <i class="fa fa-close"></i>
</div>

<!---- search field ------->
<div class="search">
    <i class="fa fa-search"></i>
    <input type="text" class="input">
</div>