body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #1a1a1a;
    font-family: Arial, sans-serif;
}

.calculator {
    width: 280px;
    background-color: #000000;
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.5);
}

.display {
    background-color: #0d0d0d;
    border: 1px solid #333;
    border-radius: 5px;
    color: #ffffff;
    font-size: 28px;
    height: 60px;
    line-height: 60px;
    margin-bottom: 15px;
    padding: 0 15px;
    text-align: right;
    overflow: hidden;
    white-space: nowrap;
    text-overflow: ellipsis;
}

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

.key {
    background-color: #1a1a1a;
    border: none;
    border-radius: 5px;
    color: #ffffff;
    cursor: pointer;
    font-size: 20px;
    height: 60px;
    transition: all 0.2s ease;
}

.key:hover {
    background-color: #333333;
}

.key:active {
    transform: scale(0.95);
}

.function {
    background-color: #0d47a1;
}

.operator {
    background-color: #1565c0;
}

.equal {
    background-color: #1e88e5;
    grid-row: span 2;
}

.zero {
    grid-column: span 2;
}

@media (max-width: 300px) {
    .calculator {
        width: 100%;
        padding: 10px;
    }

    .keypad {
        gap: 5px;
    }

    .key {
        font-size: 18px;
        height: 50px;
    }
}