CSS sliding underline

Question

I have horizontal menu on my website. I want the menu links to smoothly underline. HTML

<nav id="nav_container">
    <ul id="nav">
        <li class="nav_item"><a href="#">Sportovci</a></li>
        <li class="nav_item"><a href="#">Specialisté</a></li>
        <li class="nav_item"><a href="#">Kluby</a></li>
        <li class="nav_item"><a href="#">Obchody</a></li>
        <li class="nav_item"><a href="#">Ligy</a></li>
        <li class="nav_item"><a href="#">Články</a></li>
        <li class="nav_item"><a href="#">Kontakt</a></li>
    </ul>
</nav>           

CSS

.nav_item {
    display: inline-block;
    margin: 0 10px;
}

.nav_item:after {
    content: '';
    display: block;
    height: 1px;
    width: 0;
    background: transparent;
    transition: width .5s ease, background-color .5s ease;
}

.nav_item:hover:after {
    width: 100%;
    background: #236fe8;
}

With this code the link will underline from left to right on hover, but when i go out with mouse it doesn't smoothly go back. I think it will be some JavaScript (jQuery), but don't know how. I also want the clicked (active) link to stay underlined. How to do this?

I will be thankful for every kind of answer.

Answer 1

How about targeting the anchors instead of the .nav_item s like so:

a:after {
    content: '';
    display: block;
    height: 1px;
    width: 0;
    background: transparent;
    transition: width .5s ease, background-color .5s ease;
}

a:hover:after {
    width: 100%;
    background: #236fe8;
}

Here your updated jsFiddle .

Answer 2

replace your code with this one

.nav_item:after {
    content: '';
    display: block;
    height: 1px;
    width: 0;`enter code here`
    background: transparent;
    transition: width .5s ease, background-color .9s ease;
}

go to the following link for more help, i hope it will resolve your problem http://www.w3schools.com/cssref/css3_pr_transition-timing-function.asp