Inline elements shifting when made bold on hover

I created a horizontal menu using a HTML lists and CSS. Everything works as it should except when you hover over the links. You see, I created a bold hover state for the links, and now the menu links shift because of the bold size difference.

I encounter the same problem as this SitePoint post. However, the post does not have proper solution. I've searched everywhere for a solution and can't find one. Surely I can't be the only one trying to do this.

Does anyone have any ideas?

P.S: I don't know the width of the text in menu items so I cannot just set the width of the li items.

.nav { margin: 0; padding: 0; }
.nav li { 
    list-style: none; 
    display: inline; 
    border-left: #ffffff 1px solid; 
}
.nav li a:link, .nav li a:visited { 
    text-decoration: none; 
    color: #000; 
    margin-left: 8px; 
    margin-right: 5px; 
}
.nav li a:hover{ 
    text-decoration: none; 
    font-weight: bold; 
}
.nav li.first { border: none; }

<ul class="nav">
    <li class="first"><a href="#">item 0</a></li>
    <li><a href="#">item 1</a></li>
    <li><a href="#">item 2</a></li>
    <li><a href="#">item 3</a></li>
    <li><a href="#">item 4</a></li>
</ul>

Solution

Pre-set the width by using an invisible pseudo-element which has the same content and styling as the parent hover style. Use a data attribute, like title, as the source for content.

li {
    display: inline-block;
    font-size: 0;
}

li a {
    display:inline-block;
    text-align:center;
    font: normal 16px Arial;
    text-transform: uppercase;
}

a:hover {
    font-weight:bold;
}

/* SOLUTION */
/* The pseudo element has the same content and hover style, so it pre-sets the width of the element and visibility: hidden hides the pseudo element from actual view. */
a::before {
    display: block;
    content: attr(title);
    font-weight: bold;
    height: 0;
    overflow: hidden;
    visibility: hidden;
}

<ul>
    <li><a href="#" title="height">height</a></li>
    <li><a href="#" title="icon">icon</a></li>
    <li><a href="#" title="left">left</a></li>
    <li><a href="#" title="letter-spacing">letter-spacing</a></li>
    <li><a href="#" title="line-height">line-height</a></li>
</ul>