body {
    background: #121212;
    font-family: Arial;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.calculator {
    background: #1e1e1e;
    padding: 20px;
    border-radius: 15px;
    width: 300px;
}

#history {
    height: 80px;
    overflow-y: auto;
    color: #aaa;
    font-size: 14px;
    margin-bottom: 10px;
}

#display {
    width: 100%;
    height: 50px;
    font-size: 22px;
    text-align: right;
    margin-bottom: 10px;
    padding: 5px;
    border: none;
    outline: none;
}

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

button {
    padding: 15px;
    font-size: 16px;
    border: none;
    border-radius: 10px;
    background: #333;
    color: white;
    cursor: pointer;
}

button:hover {
    background: #555;
}