:root {
    /* Default (Light) Theme */
    --bg-color: #f4f7f6;
    --container-bg: #ffffff;
    --text-color: #333;
    --title-color: #2c3e50;
    --desc-color: #7f8c8d;
    --primary-color: #4a90e2;
    --secondary-bg: #ecf0f1;
    --secondary-text: #7f8c8d;
    --ball-shadow: rgba(0, 0, 0, 0.2);
    --card-shadow: rgba(0, 0, 0, 0.1);
    
    /* Lotto Ball Colors */
    --color-1-10: #fbc400;
    --color-11-20: #69c8f2;
    --color-21-30: #ff7272;
    --color-31-40: #aaaaaa;
    --color-41-45: #b0d840;
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --container-bg: #2d2d2d;
    --text-color: #f0f0f0;
    --title-color: #ffffff;
    --desc-color: #b0b0b0;
    --primary-color: #5da2f5;
    --secondary-bg: #3d3d3d;
    --secondary-text: #cccccc;
    --ball-shadow: rgba(0, 0, 0, 0.4);
    --card-shadow: rgba(0, 0, 0, 0.3);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    transition: background-color 0.3s, color 0.3s;
}

body {
    background-color: var(--bg-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    color: var(--text-color);
}

.container {
    background: var(--container-bg);
    padding: 2.5rem;
    border-radius: 20px;
    box-shadow: 0 10px 30px var(--card-shadow);
    text-align: center;
    max-width: 500px;
    width: 90%;
    position: relative;
}

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

#theme-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 5px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s;
}

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

h1 {
    margin-bottom: 0.5rem;
    font-size: 1.8rem;
    color: var(--title-color);
}

.description {
    color: var(--desc-color);
    margin-bottom: 2rem;
}

.ball-container {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 12px;
    min-height: 80px;
    margin-bottom: 2rem;
    align-items: center;
}

.placeholder {
    color: #bdc3c7;
    font-style: italic;
}

.ball {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    font-size: 1.2rem;
    color: white;
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
    box-shadow: inset -4px -4px 8px rgba(0, 0, 0, 0.2), 
                4px 4px 10px var(--ball-shadow);
    animation: popIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
    opacity: 0;
    transform: scale(0);
}

@keyframes popIn {
    to {
        opacity: 1;
        transform: scale(1);
    }
}

/* Ball Range Colors */
.ball.range-1 { background: radial-gradient(circle at 30% 30%, #ffd95c, var(--color-1-10)); }
.ball.range-2 { background: radial-gradient(circle at 30% 30%, #9be2ff, var(--color-11-20)); }
.ball.range-3 { background: radial-gradient(circle at 30% 30%, #ff9e9e, var(--color-21-30)); }
.ball.range-4 { background: radial-gradient(circle at 30% 30%, #cccccc, var(--color-31-40)); }
.ball.range-5 { background: radial-gradient(circle at 30% 30%, #cdec7d, var(--color-41-45)); }

.button-group {
    display: flex;
    gap: 10px;
    justify-content: center;
}

.btn {
    padding: 0.8rem 1.5rem;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s, background-color 0.2s;
}

.btn:active {
    transform: scale(0.95);
}

.btn.primary {
    background-color: var(--primary-color);
    color: white;
}

.btn.primary:hover {
    background-color: #357abd;
}

.btn.secondary {
    background-color: var(--secondary-bg);
    color: var(--secondary-text);
}

.btn.secondary:hover {
    background-color: var(--bg-color);
}

@media (max-width: 400px) {
    .ball {
        width: 40px;
        height: 40px;
        font-size: 1rem;
    }
    .container {
        padding: 1.5rem;
    }
}