JSFiddle - React, Tailwind, and code Playground

HTML

<nav>
    <div id="t1" class="t">Lvl 0-1</div>
    <div id="t2" class="t">Lvl 0-2</div>
    <div id="t3" class="t">Lvl 0-3</div>
    <div id="c1" class="c">
        <div>Lvl 1-1</div>
        <div>Lvl 1-1</div>
        <div>Lvl 1-1</div>
    </div>
    <div id="c2" class="c">
        <div>Lvl 1-2</div>
        <div>Lvl 1-2</div>
        <div>Lvl 1-2</div>
    </div>
    <div id="c3" class="c">
        <div>Lvl 1-3</div>
        <div>Lvl 1-3</div>
        <div>Lvl 1-3</div>
    </div>
</nav>

CSS

nav {
    position: relative;
}
div {
    padding: 3px 5px;
}
.t {
    position: relative;
    cursor: pointer;
}
.c {
    position: absolute;
    display: none;
    left: 0;
    width: 200px;
    background: #f0f0f0;
}
#t1:hover ~ #c1, #t2:hover ~ #c2, #t3:hover ~ #c3, .c:hover {
    display: block;
}
.t {
    display: inline-block;
}
/* helper to visualize things */
 .t:hover {
    background: #eee;
    outline: 1px dotted red;
}