style.css

* {
  color: ivory;
  text-shadow: 1px 1px 2px black;
  font-family: 'Staatliches', cursive;
  text-align: center;
}

body {
  background-image: linear-gradient( 135deg, #92FFC0 10%, #002661 100%);
  background-repeat: no-repeat;
  background-attachment: fixed;
}

.container {
  margin: auto;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.btn-grad {
  background-image: linear-gradient(to right, #16222A 0%, #3A6073  51%, #16222A  100%);
}

.btn-grad {
  padding: 15px 45px;
  text-align: center;
  transition: 0.5s;
  background-size: 200% auto;
  color: white;            
  box-shadow: 0 0 20px #eee;
  border-radius: 10px;
  display: block;
}

.btn-grad:hover {
  background-position: right center; 
  color: #fff;
  text-decoration: none;
}

.defaultCoin {
  margin: 100px;
  background: url("https://en.numista.com/catalogue/photos/royaume-uni/5f246015838b80.35326316-original.jpg");
  background-size: cover;
  border-radius: 50%;
  width: 200px;
  height: 200px;
}

.heads {
  margin: 100px;
  background: url("https://en.numista.com/catalogue/photos/royaume-uni/5f2460152d4d29.69215390-original.jpg");
  background-size: cover;
  border-radius: 50%;
  width: 200px;
  height: 200px;
}

.tails {
  margin: 100px;
  background-image: url("https://en.numista.com/catalogue/photos/royaume-uni/5f246015838b80.35326316-original.jpg");
  background-size: cover;
  border-radius: 50%;
  width: 200px;
  height: 200px;
}