@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@400;600&display=swap');body {background-color: #222;font-family: 'Poppins', sans-serif;display: flex;justify-content: center;align-items: center;height: 100vh;margin: 0;}.calculator-container {background: #333;border-radius: 12px;box-shadow: 0 8px 20px rgba(0, 0, 0, 0.3);padding: 25px;width: 320px;text-align: center;}.screen {width: 100%;height: 70px;text-align: right;font-size: 2rem;padding: 15px;border: none;background: #444;color: white;border-radius: 8px;margin-bottom: 20px;}.button-container {display: grid;grid-template-columns: repeat(4, 1fr);gap: 10px;}.btn {padding: 18px;font-size: 1.5rem;border-radius: 8px;border: none;transition: 0.3s;}.btn-pri {background-color: #666;color: white;}.btn-sec{background-color: #888;color: white;}.btn-equ {background-color: #28a745;color: white;&:hover {background-color: #218838;color: #fff;}}.btn-action {background-color: #ff4c4c;color: white;&:hover {background-color: #ff3333;color: #fff;}}.btn-pri:hover, .btn-sec:hover {background-color: #555;color: white;}