body {
    font-family: 'Roboto', Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background: linear-gradient(135deg, #89f7fe, #66a6ff);
}

.calculator {
    background-color: #ffffff;
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
    text-align: center;
    width: 100%;
    max-width: 500px;
    transition: transform 0.3s ease-in-out;
}

.calculator:hover {
    transform: scale(1.02);
}

input {
    width: 100%;
    padding: 12px 15px;
    margin: 10px 0;
    border-radius: 8px;
    border: 1px solid #cccccc;
    font-size: 1em;
    box-sizing: border-box;
    transition: border-color 0.3s ease-in-out;
}

input:focus {
    outline: none;
    border-color: #007bff;
}

.button-group {
    margin-top: 15px;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
}

.button-group button {
    flex: 1 1 calc(50% - 10px);
    margin: 5px;
    padding: 12px 10px;
    border-radius: 8px;
    border: none;
    background-color: #007bff;
    color: white;
    font-size: 1em;
    cursor: pointer;
    transition: background-color 0.3s ease-in-out, transform 0.3s ease-in-out;
    box-sizing: border-box;
}

.button-group button:hover {
    background-color: #0057b3e0;
    transform: translateY(-2px);
}

.button-group button:nth-child(8):hover{
    background-color: rgba(246, 66, 66, 0.904);
    transform: translateY(-2px);
}

.result {
    margin-top: 25px;
    font-size: 1.3em;
    font-weight: bold;
    color: #333333;
}

#error {
    margin-top: 15px;
    color: #ff4d4f;
    font-weight: bold;
}

/* Responsiveness */
@media (max-width: 500px) {
    .calculator {
        padding: 20px;
    }

    .button-group button {
        padding: 10px 8px;
        font-size: 0.9em;
    }

    .result {
        font-size: 1.2em;
    }
}