I have a very basic HTML which mix plain text and icon fonts. The problem is that icons are not exactly rendered at the same height than the text:
<div class="ui menu">
<a href="t" class="item"><i class="large home basic icon"></i><span class="nav-text"> Accueil</span></a>
<a href="" class="item"><i class="large camera retro icon"></i><span class="nav-text"> Créations</span></a>
<a class="item"><span class="nav-text">Qui-suis je </span><i class="large help basic icon"></i></a>
</div>

Any suggestion to fix it?
In this scenario, since you are working with inline-level elements, you could add vertical-align: middle to the span elements for vertical centering:
.nav-text {
vertical-align: middle;
}
Alternatively, you could set the display of the parent element to flex and set align-items to center for vertical centering:
.menu {
display: flex;
align-items: center;
}