JSFiddle - React, Tailwind, and code Playground

HTML

<div class="header-main">
    <div class="poloska"></div>
</div>

CSS

* {
    margin:0; padding:0;
}

li {
    list-style:none;
}

.header-main {
    height:300px;
    background:#83C315 url(../images/header-main-top-bg.png) top left repeat-x;
    border-radius:0 0 15px 15px;
    overflow:hidden;
}
div.poloska{
    width:100%;
    border-top:1px solid #6ea60e;
    margin-top:250px;
}
.poloska:before{
    display:block;
    content:"";
    width:100%;
    border-top:1px solid #71ab0d;
    margin-top:2px;
}
.poloska:after{
    display:block;
    content:"";
    width:100%;
    border-top:1px solid #74af0a;
    margin-top:2px;
}