<h3>Saint Vincent and the Grenadines</h3>

<div class="flag saint_vincent_and_the_grenadines">
  <div class="saint_vincent_and_the_grenadines__diamond"></div>
  <div class="saint_vincent_and_the_grenadines__hidden_diamond"></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;
}

.saint_vincent_and_the_grenadines {
  background: linear-gradient(
    to right,
    #012176 75px,
    #fbd11b 75px,
    #fbd11b 225px,
    #007d2b 0
  );

  display: grid;
  place-items: center;
}

/* Big center Green Diamond */
.saint_vincent_and_the_grenadines__diamond {
  position: relative;
  height: 150px;
  aspect-ratio: 1;
  background-color: #007c2e;
  clip-path: polygon(50% 0%, 75% 50%, 50% 100%, 25% 50%);
}

/* Crossed line between diamond */
.saint_vincent_and_the_grenadines::before,
.saint_vincent_and_the_grenadines::after {
  content: "";
  position: absolute;
  width: 8px;
  height: 100%;
  left: 50%;
  top: -10px;
  background-color: #fbd11b;
  z-index: 1;
  transform: rotate(25deg);
}

.saint_vincent_and_the_grenadines::after {
  transform: rotate(155deg);
  left: 47%;
}

.saint_vincent_and_the_grenadines__hidden_diamond {
  position: absolute;
  top: 15px;
  z-index: 1;
  left: 36%;
  height: 80px;
  aspect-ratio: 1;
  background-color: #fbd11b;
  clip-path: polygon(50% 0%, 75% 50%, 50% 100%, 25% 50%);
}