:root {
    --bg-color: #f0f2f5;
    --container-bg: white;
    --text-color: #333;
    --button-bg: #4CAF50;
    --button-hover: #45a049;
    --number-bg: #f8f8f8;
    --number-border: #ddd;
    --shadow: rgba(0,0,0,0.1);
}

body.dark-mode {
    --bg-color: #1a1a1a;
    --container-bg: #2d2d2d;
    --text-color: #f0f2f5;
    --button-bg: #2e7d32;
    --button-hover: #1b5e20;
    --number-bg: #3d3d3d;
    --number-border: #555;
    --shadow: rgba(0,0,0,0.5);
}

body {
    font-family: 'Arial', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    text-align: center;
    background-color: var(--container-bg);
    padding: 40px;
    border-radius: 10px;
    box-shadow: 0 4px 8px var(--shadow);
    transition: background-color 0.3s, box-shadow 0.3s;
}

h1 {
    color: var(--text-color);
    margin-bottom: 20px;
}

#generate {
    background-color: var(--button-bg);
    color: white;
    padding: 15px 25px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s;
}

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

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

.number {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 50px;
    height: 50px;
    background-color: var(--number-bg);
    border: 1px solid var(--number-border);
    border-radius: 50%;
    margin: 0 5px;
    font-size: 20px;
    font-weight: bold;
    color: var(--text-color);
    transition: background-color 0.3s, border-color 0.3s, color 0.3s;
}

#theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 10px 15px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    background-color: var(--container-bg);
    color: var(--text-color);
    box-shadow: 0 2px 4px var(--shadow);
    transition: background-color 0.3s, color 0.3s;
}