body {
    background-color: blue;
}
#particles-js {
  background-color: black;
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  z-index: 0;
}

.overlay {
  position: relative;
  padding: 50px;
}

.btn-actions {

}