:root {
    --background-color: #f0f2f5;
    --container-background: #fff;
    --text-color: #333;
    --number-background: #f8f9fa;
    --number-border: #dee2e6;
    --number-text: #495057;
    --button-background: #007bff;
    --button-hover: #0056b3;
    --button-text: #fff;
}

body.dark-mode {
    --background-color: #121212;
    --container-background: #1e1e1e;
    --text-color: #fff;
    --number-background: #333;
    --number-border: #555;
    --number-text: #fff;
    --button-background: #007bff;
    --button-hover: #0056b3;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: var(--background-color);
    color: var(--text-color);
    margin: 0;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    text-align: center;
    background-color: var(--container-background);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    transition: background-color 0.3s ease;
}

h1 {
    color: var(--text-color);
    margin-bottom: 1.5rem;
}

#generate, #theme-toggle {
    background-color: var(--button-background);
    color: var(--button-text);
    border: none;
    padding: 1rem 2rem;
    border-radius: 0.5rem;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease;
    margin-bottom: 1.5rem;
}

#generate:hover, #theme-toggle:hover {
    background-color: var(--button-hover);
}

#numbers-container {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.number {
    width: 50px;
    height: 50px;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: var(--number-background);
    border: 1px solid var(--number-border);
    border-radius: 50%;
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--number-text);
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

.contact-form-container {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--number-border);
}

.contact-form-container h2 {
    color: var(--text-color);
    margin-bottom: 1.5rem;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    max-width: 400px;
    margin: 0 auto;
}

.contact-form input[type="text"],
.contact-form input[type="email"],
.contact-form textarea {
    padding: 0.8rem;
    border: 1px solid var(--number-border);
    border-radius: 0.5rem;
    font-size: 1rem;
    background-color: var(--number-background);
    color: var(--number-text);
    transition: border-color 0.3s ease, background-color 0.3s ease, color 0.3s ease;
}

.contact-form textarea {
    resize: vertical;
    min-height: 100px;
}

.contact-form button[type="submit"] {
    background-color: var(--button-background);
    color: var(--button-text);
    border: none;
    padding: 1rem 2rem;
    border-radius: 0.5rem;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.contact-form button[type="submit"]:hover {
    background-color: var(--button-hover);
}