:root {
    --bg-color: #f0f2f5;
    --text-color: #333;
    --container-bg: white;
    --lotto-number-bg: #4a90e2;
    --button-bg: #4a90e2;
    --button-hover-bg: #357abd;
    --box-shadow-color: rgba(0, 0, 0, 0.1);
    --background-image-url: url('https://images.pexels.com/photos/1039832/pexels-photo-1039832.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940');
}

.dark-mode {
    --bg-color: #1a1a2e;
    --text-color: #e0e0e0;
    --container-bg: #16213e;
    --lotto-number-bg: #0f3460;
    --button-bg: #0f3460;
    --button-hover-bg: #1a1a2e;
    --box-shadow-color: rgba(0, 0, 0, 0.4);
    --background-image-url: url('https://images.pexels.com/photos/1039832/pexels-photo-1039832.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940'); /* Can be a different image for dark mode */
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    background-image: var(--background-image-url);
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    transition: background-color 0.3s ease;
}

.container {
    text-align: center;
    background-color: var(--container-bg);
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 4px 12px var(--box-shadow-color);
    transition: transform 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
    position: relative; /* For positioning theme toggle */
}

.container:hover {
    transform: translateY(-5px);
}

h1 {
    color: var(--text-color);
    margin-bottom: 30px;
    transition: color 0.3s ease;
}

.lotto-numbers {
    display: flex;
    justify-content: center;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.lotto-number {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--lotto-number-bg);
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    font-weight: bold;
    margin: 0 8px;
    box-shadow: 0 2px 6px var(--box-shadow-color);
    transition: all 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
}

#generate-btn {
    background-color: var(--button-bg);
    color: white;
    border: none;
    padding: 15px 30px;
    font-size: 18px;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease;
    box-shadow: 0 2px 6px var(--box-shadow-color);
}

#generate-btn:hover {
    background-color: var(--button-hover-bg);
    transform: translateY(-2px);
}

#generate-btn:active {
    transform: translateY(0);
}

.theme-toggle {
    position: absolute;
    top: 15px;
    right: 15px;
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    z-index: 10;
    padding: 0;
}