body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #74ebd5, #acb6e5);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    transition: background 0.5s ease;
}

.calculator {
    background: white;
    max-width: 400px;
    margin: 0 auto;
    padding: 20px;
    border-radius: 15px;
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
    text-align: center;
    animation: fadeIn 1s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

h1 {
    color: #333333;
}

.input-group {
    margin-bottom: 15px;
}

input[type="number"] {
    width: 100%;
    padding: 10px;
    margin-top: 5px;
    border: 1px solid #cccccc;
    border-radius: 5px;
    box-sizing: border-box;
    transition: border 0.3s ease, box-shadow 0.3s ease;
}

input[type="number"]:focus {
    border-color: #007bff;
    box-shadow: 0 0 8px rgba(0, 123, 255, 0.3);
    outline: none;
}

button {
    width: 100%;
    padding: 15px;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s ease, transform 0.3s ease;
}

button:hover {
    background-color: #0056b3;
    transform: translateY(-2px);
}

#result {
    margin-top: 20px;
    font-weight: bold;
    text-align: center;
    color: #007bff;
}

#history {
    margin-top: 30px;
}

#history h2 {
    color: #333333;
}

#history-list {
    list-style-type: none;
    padding: 0;
    text-align: left;
}

#history-list li {
    background: #f9f9f9;
    margin: 5px 0;
    padding: 10px;
    border: 1px solid #dddddd;
    border-radius: 5px;
    animation: fadeIn 0.5s ease;
}