body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f4f4f9;
    color: #333;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}

.container {
    background: #fff;
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 500px;
}

h1 {
    text-align: center;
    color: #4a90e2;
    margin-bottom: 1.5rem;
}

.control-group {
    margin-bottom: 1rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: bold;
}

input[type="number"], textarea {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box; /* Ensures padding doesn't affect width */
    font-family: monospace;
}

textarea {
    resize: vertical;
}

button {
    cursor: pointer;
    padding: 0.75rem 1rem;
    border: none;
    border-radius: 4px;
    font-size: 1rem;
    transition: background 0.3s;
    width: 100%;
    margin-top: 0.5rem;
}

.primary-btn {
    background-color: #4a90e2;
    color: white;
    font-weight: bold;
    margin-bottom: 1rem;
}

.primary-btn:hover {
    background-color: #357abd;
}

.secondary-btn {
    background-color: #e0e0e0;
    color: #333;
}

.secondary-btn:hover {
    background-color: #d5d5d5;
}

.secondary-btn:disabled {
    background-color: #f0f0f0;
    color: #999;
    cursor: not-allowed;
}

.output-group textarea {
    background-color: #f9f9f9;
}