* {
  box-sizing: border-box;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

body {
  margin: 0px;
  background: linear-gradient(135deg, #1e0a2d, #000000);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

#calculator-body {
  background: rgba(25, 25, 25, 0.95);
  padding: 20px;
  border-radius: 35px;
  box-shadow:
    0 25px 50px -12px rgba(0, 0, 0, 0.8),
    inset 0 1px 1px rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
}

#calculator {
  background: #121212;
  border-radius: 25px;
  width: 320px;
  box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
}

.display-outline {
  padding: 30px 20px 10px 20px;
}

#display {
  width: 100%;
  font-size: 3.5rem;
  text-align: right;
  color: #ffffff;
  background: transparent;
  border: none;
  outline: none;
  height: 80px;
  font-weight: 300;
}

#keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  padding: 15px 20px;
}

button {
  width: 100%;
  height: 60px;
  border-radius: 16px;
  border: none;
  background: #2c2c2e;
  color: #ffffff;
  font-size: 1.5rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s ease;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
}

button:hover {
  background: #3a3a3c;
  transform: translateY(-2px);
}

button:active {
  background: #1c1c1e;
  transform: translateY(1px);
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

.function-btn {
  background: #ff9f0a;
  color: #ffffff;
}

.function-btn:hover {
  background: #ffb340;
}

.function-btn:active {
  background: #cc7f08;
}

#clear-btn {
  grid-column: span 4;
  background: #ff453a;
}

#clear-btn:hover {
  background: #ff6961;
}

#clear-btn:active {
  background: #d73a31;
}

.brand {
  text-align: center;
  color: rgba(255, 255, 255, 0.2);
  padding: 0 0 20px 0;
}

.brand h1 {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 4px;
  margin: 0;
  font-weight: 600;
}