:root {
    --bg-color: #f0f2f5;
    --container-bg: #ffffff;
    --text-color: #333333;
    --btn-bg: #007bff;
    --btn-hover: #0056b3;
    --btn-text: #ffffff;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

body.dark-mode {
    --bg-color: #18191a;
    --container-bg: #242526;
    --text-color: #e4e6eb;
    --btn-bg: #3a3b3c;
    --btn-hover: #4e4f50;
    --btn-text: #e4e6eb;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s ease, color 0.3s ease;
}

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

h1 {
    font-size: 2.5rem;
    color: var(--text-color);
    margin-bottom: 20px;
}

#generate-btn {
    padding: 15px 30px;
    font-size: 1.2rem;
    color: var(--btn-text);
    background-color: var(--btn-bg);
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
    margin-top: 20px;
}

#generate-btn:hover {
    background-color: var(--btn-hover);
    box-shadow: 0 0 15px rgba(0, 123, 255, 0.5);
}

.theme-toggle {
    text-align: right;
    margin-bottom: 20px;
}

#theme-btn {
    background: none;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 5px 10px;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.3s ease;
}

#theme-btn:hover {
    background-color: var(--text-color);
    color: var(--container-bg);
}

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