не могу сдвинуть поле поиска вправо

Вот css

.site_content {
width: 880px;
overflow: hidden;
margin: 20px auto 0 auto
background-color: white;
}

.sidebar_container{
float: right;;
width: 224px;
}

вот код

<h2>Поиск</h2>
<form method="post" action="#" id="search_from" >
<input type="search" name="search_field" placeholder="ваш запрос" />
<input type="submit" class="btn" value="найти" />

</form>

file:///C:/Users/79776/Desktop/kinomonster/index.html

file:///C:/Users/79776/Desktop/%D0%9D%D0%BE%D0%B2%D0%B0%D1%8F%20%D0%BF%D0%B0%D0%BF%D0%BA%D0%B0/Screenshot_1.png скрин