<div class="baloon"></div>

.baloon {
  position: relative;
  width: 100px;
  min-height: 20px;
  padding: 10px;
  border: 5px solid darkgray;
  border-radius: 10px;
  background-color: gray;
}
.baloon::before {
  content: "";
  position: absolute;
  left: 20px;
  top: -11px;
  width: 10px;
  height: 10px;
  border: 5px solid darkgray;
  border-right: 0;
  border-bottom: 0;
  transform: rotate(45deg);
  background-color: gray;
}