:root {
    --background-gradient-start: #4facfe;
    --background-gradient-end: #00f2fe;
    --container-bg: white;
    --text-primary: #333;
    --text-secondary: #666;
    --number-bg: #eee;
    --button-bg: #4facfe;
    --button-hover-bg: #00f2fe;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

body {
    font-family: sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: linear-gradient(to right, var(--background-gradient-start), var(--background-gradient-end));
    margin: 0;
    transition: background-color 0.3s, color 0.3s;
}

body.dark-mode {
    --background-gradient-start: #232526;
    --background-gradient-end: #414345;
    --container-bg: #333;
    --text-primary: #eee;
    --text-secondary: #ccc;
    --number-bg: #555;
    --button-bg: #888;
    --button-hover-bg: #aaa;
    --shadow-color: rgba(255, 255, 255, 0.1);
}

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

h1 {
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.numbers-container {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.number {
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    background-color: var(--number-bg);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--text-primary);
    box-shadow: 0 2px 5px var(--shadow-color);
    transition: background-color 0.3s, color 0.3s;
}

#generate-btn {
    background-color: var(--button-bg);
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1rem;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: background-color 0.3s;
}

#generate-btn:hover {
    background-color: var(--button-hover-bg);
}

/* Theme Switcher */
.theme-switch-container {
    position: absolute;
    top: 1rem;
    right: 1rem;
}

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

.theme-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

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

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

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

input:focus + .slider {
    box-shadow: 0 0 1px #2196F3;
}

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

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

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