<h3>Qatar</h3>

<div class="flag qatar">
  <div class="qatar_wrap">
    <div class="qatar__triangle"></div>
  </div>
</div>

* {
  box-sizing: border-box;
  margin: 0;
}

body {
  width: 100%;
  height: 100vh;
  background-color: rgb(221, 239, 255);
  display: grid;
  place-items: center;
  font-family: cursive;
  font-weight: bold;
}

h3 {
  position: absolute;
  text-align: center;
  top: 20px;
}

/* Main Style Stars from here  */
.flag {
  position: relative;
  width: 300px;
  height: 200px;
  box-shadow: 0 0 1px rgba(0, 0, 0, 0.5);
  overflow: hidden;
}

.qatar {
  background-color: #8a1538;
}

.qatar::before {
  position: absolute;
  content: "";
  left: 0;
  width: 65px;
  height: 100%;
  background-color: white;
}

.qatar__triangle {
  position: absolute;
  left: 60px;
  top: -15px;
  background-color: rgb(255 255 255);
  width: 50px;
  height: 50px;
  clip-path: polygon(0 25%, 0 75%, 100% 51%);
}

.qatar_wrap {
  filter: drop-shadow(0 22.4px white) drop-shadow(0 22.4px white)
    drop-shadow(0 22.4px white) drop-shadow(0 22.4px white)
    drop-shadow(0 22.4px white) drop-shadow(0 22.4px white)
    drop-shadow(0 22.4px white) drop-shadow(0 22.4px white)
    drop-shadow(0 22.4px white);
}