<div class="shapes">
  <div class="shape">L</div>
  <div class="shape shape--medium">M</div>
  <div class="shape shape--small">S</div>
</div>
body {
  padding: 40px;
}

.shapes {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.shape {
  --width: 90px;
  --height: 60px;
  --font-size: 30px;
  --color: white;
  --background-color: red;
  width: var(--width);
  height: var(--height);
  font-size: var(--font-size);
  font-weight: 700;
  line-height: 1;
  color: var(--color);
  background: var(--background-color);
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}
.shape--medium {
  --width: 60px;
  --height: 40px;
  --font-size: 20px;
  --background-color: orange;
}
.shape--small { 
  --width: 30px;
  --height: 20px;
  --font-size: 10px;
  --background-color: green;
}
.shape::before {
  --size: calc(var(--height) / 2);
  content: "";
  position: absolute;
  top: 0;
  right: calc(var(--size) * -1);
  width: 0;
  height: 0;
  border-left: var(--size) solid var(--background-color);
  border-top: var(--size) solid transparent;
  border-bottom: var(--size) solid transparent;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.