JSFiddle - React, Tailwind, and code Playground

HTML

<div class="pentagon">
<div class="content">
  PUT YOUR CONTENT HERE
</div>
<div class="pentagon-pointer"></div>
</div>

CSS

.pentagon {
  background: linear-gradient(to right,black -3px, transparent 7px),
  linear-gradient( black -3px, transparent 7px),
  linear-gradient(to top , black -3px, transparent 7px),
  #4275FF;
  
  width: 200px;
  height: 200px;
  position: relative;
  /* box-shadow: inset 0 0 10px #000000; */
  z-index: 10; /* put it higher in the stacking order */
  
  padding: 15px;
  box-sizing: border-box;
}

.pentagon::before {
  content: '';
  position: absolute;
  width: 140px;
  height: 20px;
  top: 47px;
  right: -112px;
  background: linear-gradient(black -4px, transparent 7px);
  transform: rotate(45deg);
  z-index: 2;
}

.pentagon::after {
  content: "";
  position: absolute;
  bottom: 47px;
  width: 140px;
  height: 20px;
  right: -112px;
  background: linear-gradient(black -4px, transparent 7px);
  transform: rotate(135deg);
  z-index: 2;
}

.pentagon-pointer {
  display: block;
  position: absolute;
  top: 0;
  right: -98px;
  border-left: 98px solid #4275FF;
  border-bottom: 100px solid transparent;
  border-top: 100px solid transparent;
  z-index: 1;
}