:root {
    --bg-color: #f8f9fa;
    --container-bg: #ffffff;
    --text-color: #212529;
    --accent-color: #007bff;
    --button-bg: #007bff;
    --button-text: #ffffff;
    --ball-shadow: rgba(0, 0, 0, 0.1);
    --container-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    --bg-color: #121212;
    --container-bg: #1e1e1e;
    --text-color: #e0e0e0;
    --accent-color: #3700b3;
    --button-bg: #bb86fc;
    --button-text: #000000;
    --ball-shadow: rgba(0, 0, 0, 0.3);
    --container-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

* {
    box-sizing: border-box;
    transition: background-color 0.3s ease, color 0.3s ease;
}

body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
}

.container {
    text-align: center;
    background-color: var(--container-bg);
    padding: 3rem;
    border-radius: 24px;
    box-shadow: var(--container-shadow);
    width: 90%;
    max-width: 500px;
}

h1 {
    margin-bottom: 2rem;
    font-size: 2rem;
    font-weight: 700;
}

.numbers-container {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 2.5rem;
    min-height: 60px;
}

.controls {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    align-items: center;
}

#generate-button {
    padding: 12px 32px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    border: none;
    border-radius: 12px;
    background-color: var(--button-bg);
    color: var(--button-text);
    transition: transform 0.2s ease, opacity 0.2s ease;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

#generate-button:hover {
    transform: translateY(-2px);
    opacity: 0.9;
}

#generate-button:active {
    transform: translateY(0);
}

.theme-toggle {
    background: none;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 8px 16px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.9rem;
    opacity: 0.7;
    transition: opacity 0.2s;
}

.theme-toggle:hover {
    opacity: 1;
}

/* Animations */
@keyframes popIn {
    0% {
        transform: scale(0) rotate(-180deg);
        opacity: 0;
    }
    70% {
        transform: scale(1.1) rotate(10deg);
    }
    100% {
        transform: scale(1) rotate(0);
        opacity: 1;
    }
}