JSFiddle - React, Tailwind, and code Playground

HTML

<div class="carousel_gallery" id="carousel_gallery"></div>

CSS

body{
    position: relative;    

}
.carousel_gallery {
    width: 360px;
    height: 365px;
    position: absolute;
    top: 0px;
    left: 50%;
    margin-left: -185px;
    border: 1px solid red;
}
.carousel_gallery:before {
    content: "";
    width: 255px;
    height: 255px;
    margin-left: 52px;
    margin-top: 237px;
    position: absolute;
    border-bottom: 1px solid red;
    border-right: 1px solid red;
    -webkit-transform: rotate(45deg);
    background: white;
}