JSFiddle - React, Tailwind, and code Playground

HTML

<a href="javascript:void(0);" title="" class="b-question b-question--project-menu">
   <span class="b-question__content">?</span>
</a>

CSS

.b-question {
    position: absolute;
    display: block;
    border-radius: 100%;
    width: 30px;
    height: 30px;
    margin: 6px;
    opacity: .8;
    background-color: #000;
    text-align: center;
    display: -webkit-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-box-direction: normal;
    -webkit-flex-direction: column;
    -ms-flex-direction: column;
    flex-direction: column;
    -webkit-box-pack: center;
    -webkit-justify-content: center;
    -ms-flex-pack: center;
    justify-content: center;
    text-decoration: none;
    -moz-transition: all .3s ease-out;
    -o-transition: all .3s ease-out;
    -webkit-transition: all .3s ease-out;
}

.b-question__content {
    color: #fff;
    vertical-align: middle;
    font-size: 14px;
}

.b-question:hover {
    text-decoration: none;
    width: 36px;
    height: 36px;
    margin: 3px;
}