:root {
    --bg-color: #f0f0f0;
    --container-bg: transparent;
    --text-color: #333;
    --number-bg: #fff;
    --number-border: #ccc;
    --btn-bg: #e0e0e0;
    --btn-text: #333;
}

body.dark-theme {
    --bg-color: #1a1a1a;
    --text-color: #f0f0f0;
    --number-bg: #333;
    --number-border: #555;
    --btn-bg: #444;
    --btn-text: #f0f0f0;
}

body {
    font-family: sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-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: 20px;
}

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

#theme-btn {
    background-color: var(--btn-bg);
    color: var(--btn-text);
    border: none;
    padding: 8px 16px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 14px;
    transition: background-color 0.3s, color 0.3s;
}

.numbers {
    display: flex;
    gap: 10px;
    margin-top: 20px;
    justify-content: center;
    flex-wrap: wrap;
}

.number {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--number-bg);
    border: 2px solid var(--number-border);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 20px;
    font-weight: bold;
    transition: background-color 0.3s, border-color 0.3s;
}

#generate-btn {
    margin-top: 30px;
    padding: 12px 24px;
    font-size: 18px;
    cursor: pointer;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: background-color 0.2s, transform 0.1s;
}

#generate-btn:hover {
    background-color: #0056b3;
}

#generate-btn:active {
    transform: translateY(2px);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}