<div class="box">
  <div class="badge badge-top-right"><span>POPOLARE</span>
</div>
@import url(https://fonts.googleapis.com/css?family=Lato:700);

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: #f0f0f0;
}

.box {
  position: relative;
  max-width: 600px;
  width: 90%;
  height: 400px;
  background: #fff;
  box-shadow: 0 0 15px rgba(0, 0, 0, 0.4);
}

/* la base */
.badge {
  width: 150px;
  height: 150px;
  overflow: hidden;
  position: absolute;
}

.badge::before,
.badge::after {
  position: absolute;
  z-index: -1;
  content: "";
  display: block;
  border: 5px solid #2980b9;
}

.badge span {
  position: absolute;
  display: block;
  width: 225px;
  padding: 15px 0;
  background-color: #3498db;
  box-shadow: 0 5px 10px rgba(0, 0, 0, 0.1);
  color: #fff;
  font: 700 18px/1 "Lato", sans-serif;
  text-shadow: 0 1px 1px rgba(0, 0, 0, 0.2);
  text-transform: uppercase;
  text-align: center;
}

/* in alto a destra */
.badge-top-right {
  top: -10px;
  right: -10px;
}

.badge-top-right::before,
.badge-top-right::after {
  border-top-color: transparent;
  border-right-color: transparent;
}

.badge-top-right::before {
  top: 0;
  left: 0;
}

.badge-top-right::after {
  bottom: 0;
  right: 0;
}

.badge-top-right span {
  left: -25px;
  top: 30px;
  transform: rotate(45deg);
}
<!-- by Perone Luigi -->

External CSS

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External JavaScript

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