JSFiddle - React, Tailwind, and code Playground

HTML

<span>Дробный пиксель - </span><div class="d05"></div><br><br><br>
<span>Обычный пиксель - </span><div></div>

CSS

span {
    float: left;
}
div {
    width: 100px;
    height: 1px;
    background: black;
    position: relatve;
    float: left;
}
.d05 {
    margin-top: 0.5px;
}