style.css

html {
  padding: 20px;
}
body {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
  background-color: rgb(165, 221, 52);
}

h1 {
  font-family: monospace;
  font-style: oblique;
  font-variant: small-caps;
  color: rgb(128, 13, 80);
}

.container {
  display: flex;
  flex-wrap: wrap;
  width: 400px;
  border: 5px solid rebeccapurple;
  padding: 50px;
  justify-content: center;
  border-radius: 100px 0;
}

.square {
  transition: 0.8s;
  border: 1px solid black;
  background-color: rgb(223, 216, 216);
  border-radius: 7px;
  box-shadow: 1px 1px 1px rgb(53, 47, 47);
}

.btn {
  padding: 10px 40px;
  border-radius: 0 30px;
  border: none;
  background-color: aquamarine;
  color: rgb(52, 43, 168);
  font-size: large;
  font-weight: bold;
  cursor: pointer;
  transition: 1s;
}

.btn:hover {
  background-color: rgb(233, 105, 45);
  transition: 1s;
  color: #fff;
}