/* Body styling */
body {
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: #081b29;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

/* Calculator container */
.calculator {
  background: #081b29;
  padding: 0 20px 20px;
  border-radius: 20px;
  box-shadow: 0 0 20px #0ef;
  width: 300px;
}

.calculator h2 {
  margin: 0 0 15px 0;
  padding: 10px;
  text-align: center;
  color: #b1b1b1;
  user-select: none;
}

/* Screen */
.screen {
  width: 100%;
  height: 65px;
  background: #081b29;
  border-radius: 15px;
  margin-bottom: 20px;
  text-align: right;
  padding: 10px;
  font-size: 2rem;
  box-sizing: border-box;
  box-shadow: 0 0 10px #0ef;
  color: #fff;
  overflow-x: auto;
  overflow-y: auto;
}

/* Buttons grid */
.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 15px;
  user-select: none;
}

button {
  padding: 20px;
  font-size: 1.2rem;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.2s;
  background: #f9f9f9;
  transition: all 0.5s ease-in-out;
}

button:active {
  transform: translateY(3px);
  transition: all 0.1s ease-in-out;
}

button:hover {
  background: #e0e0e0;
}

button.operator {
  background: #ff6b6b;
  color: white;
}

button.equal {
  background: #1dd1a1;
  color: white;
  grid-row: span 2;
}

button.equal:hover {
  background: #10ac84;
}

button.clear {
  background: #576574;
  color: white;
}

button.clear:hover {
  background: #2f3542;
}