*, *::before, *::after {
  box-sizing: border-box;
  font-family: 'Gotham Rounded', sans-serif;
  font-weight: normal;
}

body {
  padding: 0;
  margin: 0;
  background-color: #3E5531;

.calculator-container {
  background-color: #597445;
  border-radius: 20px;
  padding: 20px;
  margin: 20px 0; 
  box-shadow: 5px 5px 15px rgba(0, 0, 0, 0.3), -5px -5px 15px rgba(62, 85, 49, 0.3); 
}

.calculator-grid {
  display: grid;
  justify-content: center;
  align-content: center;
  width: 350px;
  gap: 10px; 
  grid-template-columns: repeat(4, 80px);
  grid-template-rows: minmax(100px, auto) repeat(5, 80px);
}

.calculator-grid > button {
  cursor: pointer;
  font-size: 1.5rem; 
  border: 1px solid #E7F0DC;
  outline: none;
  background-color: #658147;
  color: #E7F0DC;
  transition: background-color 0.2s ease, box-shadow 0.2s ease;
  border-radius: 10px; 
  box-shadow: 2px 2px 5px rgba(0, 0, 0, 0.2), -2px -2px 5px rgba(62, 85, 49, 0.1); 
}

.calculator-grid > button:hover {
  background-color: #597445;
}

.span-two {
  grid-column: span 2;
}

.output {
  grid-column: 1 / -1;
  background-color: #E7F0DC; 
  display: flex;
  align-items: flex-end;
  justify-content: space-around;
  flex-direction: column;
  padding: 20px;
  word-wrap: break-word;
  word-break: break-all;
  color: #597445; 
  border-bottom: 2px solid #658147;
  border-radius: 10px; 
  box-shadow: inset 2px 2px 5px rgba(0, 0, 0, 0.2), inset -2px -2px 5px rgba(62, 85, 49, 0.1); 
}

.output .previous-operand {
  color: rgba(89, 116, 69, 0.75);
  font-size: 1.5rem;
}

.output .current-operand {
  color: #597445;
  font-size: 2.5rem;
}

@media (max-width: 768px) {
  .calculator-container {
    width: 100%;
    padding: 10px;
  }

  .calculator-grid {
    width: 100%;
    grid-template-columns: repeat(4, 1fr); 
    grid-template-rows: minmax(60px, auto) repeat(5, 1fr); 
  }

  .calculator-grid > button {
    font-size: 1.2rem; 
    padding: 10px; 
  }

  .output {
    padding: 10px;
  }

  .output .current-operand {
    font-size: 2rem; 
  }
}
}