:root {
    --background-color-light: #f4f4f9;
    --text-color-light: #333;
    --header-bg-light: #fff;
    --card-bg-light: #fff;
    --button-bg-light: #4a90e2;
    --button-text-light: #fff;
    --shadow-light: 0 4px 6px rgba(0, 0, 0, 0.1);

    --background-color-dark: #121212;
    --text-color-dark: #f4f4f9;
    --header-bg-dark: #1e1e1e;
    --card-bg-dark: #2c2c2c;
    --button-bg-dark: #61dafb;
    --button-text-dark: #121212;
    --shadow-dark: 0 4px 6px rgba(255, 255, 255, 0.1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 0;
    transition: background-color 0.3s, color 0.3s;
}

.light-mode {
    background-color: var(--background-color-light);
    color: var(--text-color-light);
}

.dark-mode {
    background-color: var(--background-color-dark);
    color: var(--text-color-dark);
}

#app {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    background-color: var(--header-bg-light);
    box-shadow: var(--shadow-light);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background-color 0.3s;
}

.dark-mode header {
    background-color: var(--header-bg-dark);
    box-shadow: var(--shadow-dark);
}

nav a {
    margin: 0 15px;
    text-decoration: none;
    color: inherit;
    font-weight: 500;
}

.theme-switch-wrapper {
    display: flex;
    align-items: center;
}

.theme-switch {
    display: inline-block;
    height: 34px;
    position: relative;
    width: 60px;
}

.theme-switch input { display: none; }

.slider {
    background-color: #ccc;
    bottom: 0;
    cursor: pointer;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    transition: .4s;
}

.slider:before {
    background-color: #fff;
    bottom: 4px;
    content: "";
    height: 26px;
    left: 4px;
    position: absolute;
    transition: .4s;
    width: 26px;
}

input:checked + .slider {
    background-color: #2196F3;
}

input:checked + .slider:before {
    transform: translateX(26px);
}

.slider.round {
    border-radius: 34px;
}

.slider.round:before {
    border-radius: 50%;
}

section {
    padding: 60px 20px;
    border-bottom: 1px solid #eee;
}

.dark-mode section {
    border-bottom: 1px solid #333;
}

h1, h2 {
    text-align: center;
}

#numbers-display {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    margin: 20px 0;
    padding: 20px;
    background-color: var(--card-bg-light);
    border-radius: 8px;
    min-height: 50px;
    box-shadow: var(--shadow-light);
}

.dark-mode #numbers-display {
    background-color: var(--card-bg-dark);
    box-shadow: var(--shadow-dark);
}

#generate-btn, form button {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 15px 30px;
    border: none;
    border-radius: 8px;
    background-color: var(--button-bg-light);
    color: var(--button-text-light);
    font-size: 1.2rem;
    cursor: pointer;
    margin: 20px auto;
    box-shadow: var(--shadow-light);
    transition: transform 0.2s, box-shadow 0.2s;
}

.dark-mode #generate-btn, .dark-mode form button {
    background-color: var(--button-bg-dark);
    color: var(--button-text-dark);
    box-shadow: var(--shadow-dark);
}

#generate-btn:hover, form button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 10px rgba(0, 0, 0, 0.15);
}

form {
    display: flex;
    flex-direction: column;
    gap: 15px;
    max-width: 500px;
    margin: 0 auto;
}

form input, form textarea {
    padding: 15px;
    border-radius: 8px;
    border: 1px solid #ccc;
    background-color: var(--card-bg-light);
    color: var(--text-color-light);
}

.dark-mode form input, .dark-mode form textarea {
    background-color: var(--card-bg-dark);
    color: var(--text-color-dark);
    border-color: #555;
}

footer {
    text-align: center;
    padding: 20px;
    margin-top: 40px;
    font-size: 0.9rem;
    color: #888;
}