JSFiddle - React, Tailwind, and code Playground

HTML

<div class="root_header"></div>
<div class="main_menu" id="obj_3">
      <a href="/about/"><span class="left"></span><b>О проекте</b><span class="right"></span></a>
      <a href="/articles/"><span class="left"></span><b>Статьи</b><span class="right"></span></a>
</div>

CSS

.root_header {
    position: absolute;
    width: 100%;
    height: 6px;
    background-image: -webkit-gradient(
         linear,
         left top,
         left bottom,
         color-stop(0, #595957),
         color-stop(1, #484848)
     );
    background-image: -o-linear-gradient(bottom, #595957 0%, #484848 100%);
    background-image: -moz-linear-gradient(bottom, #595957 0%, #484848 100%);
    background-image: -webkit-linear-gradient(bottom, #595957 0%, #484848 100%);
    background-image: -ms-linear-gradient(bottom, #595957 0%, #484848 100%);
    background-image: linear-gradient(to bottom, #595957 0%, #484848 100%);
    -webkit-box-shadow: 0px 1px 3px 0px rgba(50, 50, 50, 0.35);
    -moz-box-shadow: 0px 1px 3px 0px rgba(50, 50, 50, 0.35);
    box-shadow: 0px 1px 3px 0px rgba(50, 50, 50, 0.35);
}
.main_menu a {
    margin-right: -5px;
    text-decoration:none;
    position: relative;
    width: 130px;
    display: inline-block;
    padding: 4px 0px 6px;
    text-align: center;
    font-size: 12px;
    color: #FFFFFF;
    background: #484848;
    background-image: -webkit-gradient( linear, left top, left bottom, color-stop(0, #484848), color-stop(1, #2b2c28) );
    background-image: -o-linear-gradient(bottom, #484848 0%, #2b2c28 100%);
    background-image: -moz-linear-gradient(bottom, #484848 0%, #2b2c28 100%);
    background-image: -webkit-linear-gradient(bottom, #484848 0%, #2b2c28 100%);
    background-image: -ms-linear-gradient(bottom, #484848 0%, #2b2c28 100%);
    background-image: linear-gradient(to bottom, #484848 0%, #2b2c28 100%);
    border-bottom-right-radius: 10px;
    -webkit-border-bottom-right-radius: 17px;
    -moz-border-radius-bottomright: 10px;
    border-bottom-left-radius: 10px;
    -webkit-border-bottom-left-radius: 17px;
    -moz-border-radius-bottomleft: 10px;
}

.main_menu a:hover
{
    background: #2b2c28;
    background-image: -webkit-gradient( linear, left top, left bottom, color-stop(0, #2b2c28), color-stop(1, #484848) );
   ...