* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #90e0ef, #a7c957);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}
.calculator {
  background-color: #003d5b;
  width: 50vmin;
  display: flex;
  flex-direction: column;
  align-items: center;
  border-radius: 2vmin;
  box-shadow: 0 1.5vmin 4vmin rgba(0, 0, 0, 0.5);
}

#display {
  width: 90%;
  padding: 2vmin;
  margin: 2vmin 0;
  font-size: 3vmin;
  outline: none;
  border: none;
  text-align: right;
  box-shadow: inset 0 0.5vmin 1vmin rgba(0, 0, 0, 1);
}

.button-container {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  gap: 2vmin;
  padding: 2vmin;
}

.btn {
  width: 12vmin;
  height: 12vmin;
  background-color: #00b4d8;
  border: none;
  color: white;
  font-size: 3vmin;
  border-radius: 1vmin;
  padding: 2vmin;
  cursor: pointer;
  transition: transform 0.1s ease, background-color 0.2s ease;
}

.btn:hover {
  background-color: #0077b6;
  transform: scale(1.05);
}

.btn:active {
  background-color: #023e8a;
}