:root {
    --bg-color: #f0f0f0;
    --text-color: #333;
    --container-bg-color: #fff;
    --number-bg-color: #eee;
    --history-item-bg-color: #f9f9f9;
    --box-shadow-color: rgba(0, 0, 0, 0.1);
}

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

body.dark-mode {
    --bg-color: #333;
    --text-color: #f0f0f0;
    --container-bg-color: #444;
    --number-bg-color: #555;
    --history-item-bg-color: #3a3a3a;
    --box-shadow-color: rgba(255, 255, 255, 0.1);
}

.container {
    background-color: var(--container-bg-color);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 8px var(--box-shadow-color);
    text-align: center;
    transition: background-color 0.3s;
}

h1 {
    margin-bottom: 2rem;
}

.generator {
    margin-bottom: 2rem;
}

.numbers-display {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.number {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--number-bg-color);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5rem;
    font-weight: bold;
    transition: background-color 0.3s;
}

#generate-btn {
    background-color: #4CAF50;
    color: white;
    padding: 1rem 2rem;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s;
}

#generate-btn:hover {
    background-color: #45a049;
}

.history h2 {
    margin-bottom: 1rem;
}

#history-list {
    list-style: none;
    padding: 0;
    max-height: 200px;
    overflow-y: auto;
}

#history-list li {
    background-color: var(--history-item-bg-color);
    padding: 0.5rem;
    border-radius: 5px;
    margin-bottom: 0.5rem;
    transition: background-color 0.3s;
}