body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f0f4f8;
    font-family: 'Arial', sans-serif;
    margin: 0;
}

.calculator {
    background-color: #fff;
    border-radius: 20px;
    box-shadow: 0px 0px 20px rgba(0, 0, 0, 0.1);
    padding: 20px;
    width: 320px;
}

.display {
    text-align: right;
    margin-bottom: 10px;
}

.display input {
    width: 90%;
    padding: 15px;
    border-radius: 10px;
    border: none;
    background-color: #f0f4f8;
    font-size: 24px;
    text-align: right;
}

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

button.btn {
    padding: 20px;
    border-radius: 10px;
    border: none;
    background-color: #e0e4e8;
    font-size: 18px;
    cursor: pointer;
    transition: background-color 0.3s;
}

button.btn:hover {
    background-color: #d0d4d8;
}

button.btn:active {
    background-color: #c0c4c8;
}

button.zero {
    grid-column: span 2;
}

button.equal {
    background-color: #ff8c94;
    color: #fff;
    font-weight: bold;
}

button.equal:hover {
    background-color: #ff6b6b;
}

button.operator {
    background-color: #fcd4d3;
}

button.operator:hover {
    background-color: #fcd4d3;
}