* {
    font-family: sans-serif;
    max-width: 400px;
    text-align: center;
    margin: 5px auto;
    background-color: #f7f7f7;
    border-radius: 12px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

button {
    width: 100%;
    margin-right: 10px;
}

#reseult {
    height: 50px;
    background-color: #fff;
    border: 2px solid #ccc;
    font-size: 24px;
    padding: 10px;
    margin-bottom: 10px;
    border-radius: 8px;
}

#buttons td {
    padding: 5px;
}

#buttons button:hover {
    background-color: #d0d0d0;
}

#buttons button[data-key="="]:hover {
    background-color: #45a049;
}

#buttons button[data-key="AC"] {
    background-color: #f44336;
    color: white;
}

#buttons button[data-key="AC"]:hover {
    background-color: #e53935;
}

#formula_history {
    margin-top: 20px;
    padding-left: 20px;
    list-style: disc;
    background-color: #fff;
    border: 1px solid #ccc;
    border-radius: 6px;
    padding: 10px;
}

#remove_history {
    margin-top: 10px;
    padding: 8px 16px;
    background-color: #607d8b;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
}

#remove_history:hover {
    background-color: #546e7a;
}