:root {
    --main-bg-color: #f0f0f0;
    --container-bg-color: #fff;
    --text-color: #333;
    --button-bg-color: #4CAF50;
    --button-text-color: #fff;
    --number-bg-color: #eee;
    --number-text-color: #333;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

body.dark-mode {
    --main-bg-color: #121212;
    --container-bg-color: #1e1e1e;
    --text-color: #f0f0f0;
    --button-bg-color: #BB86FC;
    --button-text-color: #121212;
    --number-bg-color: #333;
    --number-text-color: #f0f0f0;
    --shadow-color: rgba(255, 255, 255, 0.1);
}

body {
    font-family: Arial, sans-serif;
    background-color: var(--main-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 {
    position: relative;
    background-color: var(--container-bg-color);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 8px var(--shadow-color);
    text-align: center;
    transition: background-color 0.3s;
}

h1 {
    margin-bottom: 1.5rem;
}

.numbers-container {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
    min-height: 50px;
}

.number {
    width: 50px;
    height: 50px;
    background-color: var(--number-bg-color);
    color: var(--number-text-color);
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5rem;
    font-weight: bold;
    animation: fadeIn 0.5s ease-in-out;
    transition: background-color 0.3s, color 0.3s;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(0.5);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

button {
    background-color: var(--button-bg-color);
    color: var(--button-text-color);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s, color 0.3s;
}

button:hover {
    opacity: 0.9;
}

.theme-btn {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background-color: transparent;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    width: 40px;
    height: 40px;
    padding: 0;
    border-radius: 50%;
    font-size: 1.2rem;
    display: flex;
    justify-content: center;
    align-items: center;
}