body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    padding: 0;
    font-family: 'Arial', sans-serif;
    background: linear-gradient(135deg, #3498db, #9b59b6);
    transition: background 0.5s ease;
}

.container {
    width: 420px;
}

.calc {
    background: #2c3e50;
    padding: 20px;
    border-radius: 15px;
    box-shadow: 0px 10px 20px rgba(0, 0, 0, 0.2);
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 1.0s ease forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.calc__buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

calc__button-clear {
    grid-column: 1 / 2;
}

.calc__display {
    grid-column: 2 / 5;
}

.calc__display {
    background: white;
    color: #34495e;
    font-size: 1.8rem;
    text-align: right;
    padding: 15px;
    border-radius: 5px;
    overflow: hidden;
}

.calc__button {
    background: #34495e;
    border: none;
    color: white;
    padding: 15px;
    font-size: 1.2rem;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.3s ease, transform 0.2s ease;
}

.calc__button:hover {
    background: #1abc9c;
    transform: scale(1.1);
}

.calc__button:active {
    transform: scale(0.95);
    transition: transform 0.3s ease;
}

.calc__button-operator {
    background: #e67e22;
    transition: transform 0.3s ease;
}

.calc__button-operator:hover {
    background: #d35400;
    transform: rotate(360deg);
}

.calc__button-clear {
    background: #e74c3c;
}

.calc__button-clear:hover {
    background: #c0392b;
}

.calc__button-equals {
    background: #2ecc71;
}

.calc__button-equals:hover {
    background: #27ae60;
}