:root {
    --bg-color: #f0f0f0;
    --card-bg: #fff;
    --text-color: #333;
    --hero-text-color: #333;
    --number-bg: #eee;
    --number-text: #333;
    --btn-bg: #007bff;
    --btn-hover: #0056b3;
    --shadow: rgba(0, 0, 0, 0.1);
}

body.dark-mode {
    --bg-color: #121212;
    --card-bg: #1e1e1e;
    --text-color: #e0e0e0;
    --hero-text-color: #ffffff;
    --number-bg: #333;
    --number-text: #e0e0e0;
    --shadow: rgba(0, 0, 0, 0.5);
}

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

.container {
    text-align: center;
}

.hero-text {
    font-size: 3rem;
    font-weight: 800;
    color: var(--hero-text-color);
    margin-bottom: 2rem;
}

.card {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 10px 20px var(--shadow), 0 6px 6px var(--shadow);
    transition: transform 0.2s, background-color 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-5px);
}

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

.number, .placeholder {
    width: 50px;
    height: 50px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 600;
    border-radius: 50%;
    background-color: var(--number-bg);
    color: var(--number-text);
    transition: background-color 0.3s, color 0.3s;
}

.generate-btn {
    display: inline-flex;
    align-items: center;
    padding: 0.8rem 1.5rem;
    border: none;
    border-radius: 8px;
    background-color: var(--btn-bg);
    color: #fff;
    font-size: 1.2rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(0, 123, 255, 0.3);
    transition: all 0.2s;
}

.generate-btn:hover {
    background-color: var(--btn-hover);
    box-shadow: 0 6px 8px rgba(0, 123, 255, 0.4);
    transform: translateY(-2px);
}

.generate-btn svg {
    margin-right: 0.5rem;
}

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

#theme-btn {
    background: none;
    border: 2px solid var(--btn-bg);
    color: var(--btn-bg);
    padding: 8px 16px;
    border-radius: 20px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s;
}

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