JSFiddle - React, Tailwind, and code Playground

HTML

<div class="dropdown">
    <div>File</div>
    <ul>
        <li>New...</li>
        <li>Open</li>
        <li>Open As...</li>
        <li>Save</li>
    </ul>
</div>
 
<div class="dropdown">
    <div>Menu</div>
    <ul>
        <li>menu #1</li>
        <li>menu #2</li>
        <li>menu #3</li>
    </ul>
</div>

<div class="dropdown">
    <div>Any</div>
    <ul class="right-open">
        <li>menu #1</li>
        <li>menu #2</li>
        <li>menu #3</li>
    </ul>
</div>

CSS

body { background: #bbb; font-family: "Calibri";}

.dropdown {
    display: inline-block;
    position: relative;
}

.dropdown ul {
    position: absolute;
   /*  top: 25px; */
    padding: 0px;
    margin: 0px;
    list-style: none;
    visibility: hidden;
    opacity: 0;
    background: #fff;
    width: 100px;
    padding: 5px 0px;
    border-top-right-radius: 5px;
    border-bottom-left-radius: 5px;
    border-bottom-right-radius: 5px;
    box-shadow: 0px 1px 1px 0px #000;
    transition: all 0.3s 0s;
    z-index: 9;
}

ul.right-open {
    right: 0px !important;
    border-top-left-radius: 5px !important;
    border-top-right-radius: 0px !important;
}

.dropdown li {
    padding: 0px 5px;
    cursor: pointer;
}

.dropdown li:hover {
    background: #1560bd;
    color: #fff;
}

.dropdown div {
    display: inline-block;
    font-size: 14px;
    height: 20px;
    line-height: 20px;
    border-radius: 5px;
    background: #eee;
    padding: 5px;
    box-shadow: 0px 0px 1px 0px #000;
    cursor: default;
    transition: background 0.3s 0s;
}

.dropdown:hover > div {
    background: #fff;
}

.dropdown:hover > ul {
    visibility: visible;
    opacity: 1;
}

JavaScript

/* нe единой строчки JS */