how to slideToggle an input with it's placeholder

guys, I wrote a code that whenever I click on a button (that plus sign) my input should slide but as you see my running code whenever I click that button first it start sliding the input until it reaches the placeholder then it starts sliding placeholder as a separate element they don't slide together so I wanted to know is there any way to fix this?that only input slides and placeholder slide with it.

HTML:

<div id="container">
<h1>LIST<i class="fa fa-plus" aria-hidden="true"></i></h1>
<input type="text" placeholder="Add New Todo"></div>

jQuery

    var plusSign = $("h1 i")
plusSign.on("click",function(event){
    $('input:text').slideToggle(3000);
})

https://jsfiddle.net/Ghost007D/aduLw0u3/1/