horizonevent/src/App.css

body {
  background: transparent url(./img/bg.jpg) no-repeat;
}

.App {
  text-align: center;
  height: 100vh;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.App .Main {
  height: 60vh;
  width: 40%;
  background: #fff;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.App .Main form {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}