body {
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  margin: auto;
  height: 100vh;
}

.top {
  display: flex;
  flex-direction: column;
  background: lightgray;
  padding: 0 20px;
}

.title {
  color: gray;
  margin: 0;
  text-align: center;
  font-size: 1.5rem;
  padding: 10px 0;
}

.calculator {
  background: #000;
  padding: 0 10px 20px;
  border-radius: 0 0 3rem 3rem;
  box-shadow: 0 30px 15px rgba(0, 0, 0, 0.1);
  width: auto;
  display: flex;
  flex-direction: column;
}

#display {
  font-size: 1rem;
  text-align: left;
  margin-bottom: 1.25rem;
  padding: 10px;
  background: whitesmoke;
  color: black;
  font-weight: bold;
}

.bottom {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.625rem;
  padding: 1.25rem 1.25rem 1.375rem;
}

.btn {
  border: 1px solid white;
  cursor: pointer;
  transition: background 0.3s ease;
}

.btn:hover {
  background: #ddd;
}

.light {
  background: white;
  border-radius: 0.25rem 0.25rem 0.75rem 0.75rem;
  color: black;
  font-weight: bolder;
  font-size: 1.5rem;
  padding: 0.3125rem;
}

.dark {
  background: black;
  border-radius: 0.25rem 0.25rem 0.75rem 0.75rem;
  color: white;
  font-size: 0.75rem;
}

#clear {
  padding: 0.3126rem 0;
}

.gray {
  background: gray;
  border-radius: 0.25rem 0.25rem 0.75rem 0.75rem;
  color: white;
  font-size: 1.5rem;
}

.hidden {
  visibility: hidden;
}

#enter {
  grid-column: span 4;
}