:root {
    --bg-color: #f0f0f0;
    --text-color: #333;
    --btn-bg: #fff;
    --btn-text: #333;
    --container-bg: #fff;
    --container-shadow: rgba(0, 0, 0, 0.1);
}

[data-theme='dark'] {
    --bg-color: #1a1a1a;
    --text-color: #f0f0f0;
    --btn-bg: #333;
    --btn-text: #f0f0f0;
    --container-bg: #2a2a2a;
    --container-shadow: rgba(0, 0, 0, 0.5);
}

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

.container {
    text-align: center;
    padding: 40px;
    background-color: var(--container-bg);
    border-radius: 12px;
    box-shadow: 0 4px 12px var(--container-shadow);
    transition: background-color 0.3s, box-shadow 0.3s;
}

#generate-btn, #theme-toggle {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    background-color: var(--btn-bg);
    color: var(--btn-text);
    border: 1px solid #ccc;
    border-radius: 4px;
    margin: 5px;
    transition: background-color 0.3s, color 0.3s;
}

#theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
}

#numbers-container {
    margin-top: 20px;
    font-size: 24px;
    font-weight: bold;
    min-height: 1.2em;
}