* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: white;
  background: black;
  min-height: 100vh; /* ensures full height center */
  font-family: Arial, sans-serif;
  flex-wrap: wrap;
}
.counter {
  background: rgba(0, 0, 0, 0.459);
  margin: 30px auto;
  padding: 50px;
  font-size: 1.5rem;
  max-width: 700px;
  width: 100%;
  box-shadow: 0 0 10px white;
  border-radius: 13px;
  border: 2px solid;
}
#btn {
  background: black;
  padding: 10px 20px;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: bold;
  margin-top: 30px;
  border: 2px solid white;
  color: aliceblue;
  transition: background 0.3s, box-shadow 0.3s;
}
#btn:hover {
  cursor: pointer;
  box-shadow: 0 0 20px rgb(207, 207, 207);
  background: rgb(207, 207, 207);
  color: black;
}