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

body {
  font-family: 'Poppins', sans-serif;
  background: linear-gradient(135deg, #0f0f1e 0%, #1a1a2e 50%, #0f0f1e 100%);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  color: #fff;
  padding: 20px;
}

.calculator {
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(30px);
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-radius: 30px;
  padding: 30px;
  box-shadow:
    0 20px 50px rgba(0, 0, 0, 0.3),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
  max-width: 350px;
  width: 100%;
}

.display {
  width: 100%;
  background: rgba(255, 255, 255, 0.08);
  border: 2px solid rgba(255, 255, 255, 0.25);
  border-radius: 15px;
  padding: 20px;
  font-size: 2rem;
  font-weight: 600;
  color: #fff;
  text-align: right;
  margin-bottom: 25px;
  transition: all 0.3s ease;
  font-family: 'Poppins', sans-serif;
}

.display:focus {
  outline: none;
  box-shadow:
    0 10px 30px rgba(0, 0, 0, 0.2),
    inset 0 1px 2px rgba(255, 255, 255, 0.2);
  background: rgba(255, 255, 255, 0.12);
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

.number {
  padding: 20px;
  font-size: 1.3rem;
  font-weight: 600;
  border: 2px solid rgba(255, 255, 255, 0.35);
  border-radius: 15px;
  cursor: pointer;
  transition: all 0.3s ease;
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
  backdrop-filter: blur(20px);
  box-shadow:
    0 5px 15px rgba(0, 0, 0, 0.15),
    inset 0 1px 2px rgba(255, 255, 255, 0.2);
}

.number:hover {
  transform: translateY(-3px);
  background: rgba(255, 255, 255, 0.18);
  border-color: rgba(255, 255, 255, 0.5);
  box-shadow:
    0 10px 25px rgba(0, 0, 0, 0.2),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
}

.number:active {
  transform: translateY(-1px);
  box-shadow:
    0 5px 15px rgba(0, 0, 0, 0.15),
    inset 0 1px 2px rgba(255, 255, 255, 0.2);
}

/* Clear button - Red */
#clear {
  background: rgba(255, 76, 76, 0.2);
  border-color: rgba(255, 76, 76, 0.5);
}

#clear:hover {
  background: rgba(255, 76, 76, 0.35);
  box-shadow:
    0 10px 25px rgba(255, 76, 76, 0.3),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
  border-color: rgba(255, 76, 76, 0.7);
}

/* Divide button - Yellow */
#divide {
  background: rgba(255, 193, 7, 0.2);
  border-color: rgba(255, 193, 7, 0.5);
}

#divide:hover {
  background: rgba(255, 193, 7, 0.35);
  box-shadow:
    0 10px 25px rgba(255, 193, 7, 0.3),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
  border-color: rgba(255, 193, 7, 0.7);
}

/* Multiply button - Orange */
#multiply {
  background: rgba(255, 152, 0, 0.2);
  border-color: rgba(255, 152, 0, 0.5);
}

#multiply:hover {
  background: rgba(255, 152, 0, 0.35);
  box-shadow:
    0 10px 25px rgba(255, 152, 0, 0.3),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
  border-color: rgba(255, 152, 0, 0.7);
}

/* Subtract button - Red */
#subtract {
  background: rgba(244, 67, 54, 0.2);
  border-color: rgba(244, 67, 54, 0.5);
}

#subtract:hover {
  background: rgba(244, 67, 54, 0.35);
  box-shadow:
    0 10px 25px rgba(244, 67, 54, 0.3),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
  border-color: rgba(244, 67, 54, 0.7);
}

/* Add button - Green */
#add {
  background: rgba(76, 175, 80, 0.2);
  border-color: rgba(76, 175, 80, 0.5);
}

#add:hover {
  background: rgba(76, 175, 80, 0.35);
  box-shadow:
    0 10px 25px rgba(76, 175, 80, 0.3),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
  border-color: rgba(76, 175, 80, 0.7);
}

/* Equals button - Cyan */
#equals {
  background: rgba(0, 188, 212, 0.2);
  border-color: rgba(0, 188, 212, 0.5);
}

#equals:hover {
  background: rgba(0, 188, 212, 0.35);
  box-shadow:
    0 10px 25px rgba(0, 188, 212, 0.3),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
  border-color: rgba(0, 188, 212, 0.7);
}

/* Decimal button - Purple */
#decimal {
  background: rgba(156, 39, 176, 0.2);
  border-color: rgba(156, 39, 176, 0.5);
}

#decimal:hover {
  background: rgba(156, 39, 176, 0.35);
  box-shadow:
    0 10px 25px rgba(156, 39, 176, 0.3),
    inset 0 1px 2px rgba(255, 255, 255, 0.3);
  border-color: rgba(156, 39, 176, 0.7);
}

/* Zero button */
#zero {
  background: rgba(255, 255, 255, 0.12);
}

@media (max-width: 500px) {
  .calculator {
    padding: 25px;
    max-width: 100%;
  }

  .display {
    font-size: 1.8rem;
    padding: 15px;
    margin-bottom: 20px;
  }

  .number {
    padding: 18px;
    font-size: 1.1rem;
  }

  .buttons {
    gap: 10px;
  }
}

@media (max-width: 350px) {
  .calculator {
    padding: 20px;
  }

  .display {
    font-size: 1.5rem;
    padding: 12px;
  }

  .number {
    padding: 15px;
    font-size: 1rem;
  }

  .buttons {
    gap: 8px;
  }
}