body {
    font-family: Arial, Helvetica, sans-serif;
    background: #f5f5f5;
    color: #333;
    margin: 0;
    padding: 0;
}

.container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    text-align: center;
}

h1 {
    font-size: 2em;
    font-weight: 600;
    color: #222;
    margin-bottom: 10px;
}

form, .result-box {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px;
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 6px rgba(0,0,0,0.1);
    gap: 10px;
}

.number-input {
    padding: 8px 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
    width: 150px;
    font-size: 1em;
    outline: none;
    transition: border-color 0.3s ease;
}

.number-input:focus {
    border-color: #0077cc;
}

.submit-btn {
    padding: 10px 20px;
    background: #0077cc;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1em;
    transition: background 0.3s ease;
}

.submit-btn:hover {
    background: #005fa3;
}

a {
    margin-top: 20px;
    color: #0077cc;
    text-decoration: none;
    font-weight: bold;
}

a:hover {
    text-decoration: underline;
}