:root {
    --bg-color: #f8f9fa;
    --container-bg: #ffffff;
    --text-color: #212529;
    --btn-bg: #007bff;
    --btn-hover: #0056b3;
    --lotto-num-bg: #ffc107;
    --lotto-num-text: #212529;
    --border-color: #dee2e6;
}

.dark-mode {
    --bg-color: #121212;
    --container-bg: #1e1e1e;
    --text-color: #e9ecef;
    --btn-bg: #375a7f;
    --btn-hover: #2b4764;
    --lotto-num-bg: #fd7e14;
    --lotto-num-text: #ffffff;
    --border-color: #444444;
}

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

.container {
    position: relative;
    text-align: center;
    padding: 3rem 2rem;
    background-color: var(--container-bg);
    border-radius: 16px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    width: 90%;
    max-width: 400px;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--border-color);
}

.dark-mode .container {
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

h1 {
    margin-bottom: 2rem;
    font-size: 1.8rem;
    color: var(--text-color);
}

.theme-btn {
    position: absolute;
    top: 1rem;
    right: 1rem;
    padding: 0.5rem 0.8rem;
    background-color: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.2s ease;
}

.theme-btn:hover {
    background-color: rgba(128, 128, 128, 0.1);
}

#generator-btn {
    width: 100%;
    padding: 1rem;
    font-size: 1.1rem;
    font-weight: 600;
    color: white;
    background-color: var(--btn-bg);
    border: none;
    border-radius: 12px;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.1s ease;
}

#generator-btn:hover {
    background-color: var(--btn-hover);
}

#generator-btn:active {
    transform: scale(0.98);
}

.lotto-numbers {
    display: flex;
    justify-content: center;
    margin-top: 2.5rem;
    flex-wrap: wrap;
    gap: 12px;
}

.lotto-number {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    background-color: var(--lotto-num-bg);
    color: var(--lotto-num-text);
    font-size: 1.2rem;
    font-weight: bold;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    animation: popIn 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
}

@keyframes popIn {
    0% { transform: scale(0); opacity: 0; }
    100% { transform: scale(1); opacity: 1; }
}