<div class="card">
  <h1 class="card__title">My awesome card</h1>
  <p class="card__text">Lorem ipsum dolor sit amet consectetur adipisicing elit. Exercitationem, ipsa sit obcaecati unde quas suscipit molestias ad tempora reiciendis sed est iure perspiciatis! Ducimus, vitae. Sequi aspernatur nulla corrupti voluptates.</p>
</div>

:root {
  --primary-color: #5439ab;
}

body {
  min-height: 100vh;
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  font: 16px 'Segoe UI', Arial, Helvetica, sans-serif;
  background: #222222;
}

.card {
  --corner-size: 60px;
  --border-width: 10px;
  
  position: relative;
  width: 320px;
  height: 480px;
  margin: 40px;
  padding: calc(40px + var(--border-width));
  box-sizing: border-box;
  border-radius: 20px;
  background: #ffffff;
  clip-path: polygon(
    var(--corner-size) 0%,
    100% 0%,
    100% 100%,
    0% 100%,
    0% var(--corner-size)
  );
  box-shadow: inset 0 0 0 var(--border-width) var(--primary-color);
}

.card::after {
  position: absolute;
  top: 0;
  left: 0;
  width: var(--border-width);
  height: calc(var(--corner-size) * 2);
  transform: rotate(45deg) translateY(calc(var(--corner-size) * -0.65));
  background: var(--primary-color);
  content: '';
}

.card__title {
  margin: 0 0 40px 0;
  text-align: center;
  font-weight: 500;
  color: var(--primary-color);
  text-shadow: 0 1px 1px rgba(0, 0, 0, 0.1), 0 2px 2px rgba(0, 0, 0, 0.1);
}

.card__text {
  margin: 0;
  text-indent: 2em;
  text-align: justify;
}