body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f0f0f0;
    font-family: Arial, sans-serif;
    margin: 0;
}

.calculator {
    border-radius: 10px;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.2);
    background: #ffffff;
    overflow: hidden;
    width: 300px;
}

.display {
    background: #333;
    color: #fff;
    padding: 20px;
    font-size: 2em;
    text-align: right;
    border-bottom: 2px solid #ddd;
}

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

.btn {
    background: #f9f9f9;
    border: 1px solid #ddd;
    padding: 20px;
    font-size: 1.5em;
    cursor: pointer;
    transition: background 0.3s;
}

.btn:hover {
    background: #ddd;
}

.btn-equal {
    background: #ff9500;
    color: white;
    grid-column: span 4;
}

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

.btn-dot {
    background: #ff9500;
    color: white;
}

.btn-equal:hover,
.btn-dot:hover {
    background: #e68900;
}