body {
    margin: 0;
    padding: 0; /* Adjust padding if needed to fit the content perfectly */
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: transparent;
}

.calculator {
    background: #fff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    max-width: 400px;
    width: 100%;
}

.calculator h1 {
    margin-bottom: 20px;
    font-size: 24px;
}

.input-group {
    display: flex;
    align-items: center;
    margin-bottom: 10px;
}

.input-group label {
    width: 150px;
    margin-right: 10px;
    font-size: 14px;
}

.input-group input {
    flex: 1;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
}

.input-group input:disabled {
    background-color: #e9ecef;
}

.buttons {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
}

.buttons button {
    padding: 10px;
    background: #28a745;
    color: #fff;
    border: none;
    border-radius: 5px;
    font-size: 16px;
    cursor: pointer;
    flex: 1;
    margin: 0 5px;
}

.buttons button:hover {
    background: #218838;
}

.history {
    margin-top: 20px;
}

.history h2 {
    font-size: 18px;
    margin-bottom: 10px;
}

.history ul {
    list-style: none;
    padding: 0;
}

.history li {
    background: #f4f4f4;
    padding: 10px;
    margin-bottom: 5px;
    border-radius: 5px;
    font-size: 14px;
}