Frame with triangle

<div class="angle-wrapper"></div>

<style scoped>
.angle-wrapper {
    
    
  width: 300px;
  height: 200px;
  position: relative;
  background: rgb(148, 34, 34);
  margin-left: 30px;
}
.angle-wrapper:before {
    
    
  content: "";
  width: 0;
  height: 0;
  border: 10px solid transparent;
  border-right-color: rgb(148, 34, 34);
  position: absolute;
  right: 100%;
  top: 50%;
  margin-top: -20px;
}
</style>