body {
    font-family: sans-serif;
    background-color: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    text-align: center;
    background-color: white;
    padding: 40px;
    border-radius: 15px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1), 0 6px 6px rgba(0, 0, 0, 0.1);
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

h1 {
    color: #333;
    margin-bottom: 30px;
    transition: color 0.3s ease;
}

.numbers-container {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 30px;
}

.number {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background-color: #eee;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    font-weight: bold;
    color: #333;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    transition: background-color 0.3s ease, color 0.3s ease, box-shadow 0.3s ease;
}

#generate-btn {
    background-color: #4CAF50;
    color: white;
    padding: 15px 30px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 18px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    transition: all 0.3s ease;
}

#generate-btn:hover {
    background-color: #45a049;
    box-shadow: 0 0 20px rgba(76, 175, 80, 0.7);
}

#theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    background: none;
    border: 2px solid #ccc;
    border-radius: 50%;
    width: 48px;
    height: 48px;
    font-size: 24px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    justify-content: center;
    align-items: center;
}

#theme-toggle:hover {
    transform: scale(1.1);
}

/* Dark mode */
body.dark {
    background-color: #1a1a2e;
}

body.dark .container {
    background-color: #16213e;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.4), 0 6px 6px rgba(0, 0, 0, 0.3);
}

body.dark h1 {
    color: #e0e0e0;
}

body.dark .number {
    background-color: #0f3460;
    color: #e0e0e0;
    box-shadow: 0 4px 8px rgba(0,0,0,0.3);
}

body.dark #theme-toggle {
    border-color: #555;
}

body.dark #generate-btn {
    box-shadow: 0 4px 8px rgba(0,0,0,0.4);
}