:root {
    --bg-gradient: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    --container-bg: rgba(255, 255, 255, 0.95);
    --text-color: #2c3e50;
    --row-bg: #f8f9fa;
    --btn-primary: linear-gradient(135deg, #007bff, #0056b3);
    --btn-secondary: #e9ecef;
    --btn-secondary-text: #495057;
    --shadow: rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    --bg-gradient: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    --container-bg: rgba(30, 39, 46, 0.95);
    --text-color: #ecf0f1;
    --row-bg: #2f3542;
    --btn-primary: linear-gradient(135deg, #4834d4, #686de0);
    --btn-secondary: #3d3d3d;
    --btn-secondary-text: #ffffff;
    --shadow: rgba(0, 0, 0, 0.4);
}

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

.container {
    text-align: center;
    background-color: var(--container-bg);
    padding: 2.5rem 2rem;
    border-radius: 24px;
    box-shadow: 0 20px 40px var(--shadow);
    width: 90%;
    max-width: 480px;
    transition: all 0.3s ease;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2.5rem;
}

h1 {
    color: var(--text-color);
    margin: 0;
    font-size: 1.8rem;
    font-weight: 800;
    letter-spacing: -0.5px;
}

.theme-switch {
    position: fixed;
    top: 20px;
    right: 20px;
    background: var(--container-bg);
    color: var(--text-color);
    border: 1px solid var(--btn-secondary);
    padding: 8px 16px;
    border-radius: 30px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 8px;
    box-shadow: 0 4px 10px var(--shadow);
    transition: all 0.3s ease;
    z-index: 1000;
}

.theme-switch:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 15px var(--shadow);
}

.lotto-numbers {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    margin-bottom: 2.5rem;
    min-height: 100px;
}

.lotto-row {
    display: flex;
    justify-content: center;
    gap: 12px;
    padding: 10px;
    background: var(--row-bg);
    border-radius: 100px;
    width: 100%;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.05);
}

.button-group {
    display: flex;
    gap: 12px;
    justify-content: center;
}

#generate-btn {
    background: var(--btn-primary);
    color: #fff;
    border: none;
    padding: 16px 32px;
    font-size: 1.1rem;
    font-weight: 700;
    border-radius: 14px;
    cursor: pointer;
    transition: all 0.2s ease;
    flex: 2;
}

#reset-btn {
    background: var(--btn-secondary);
    color: var(--btn-secondary-text);
    border: none;
    padding: 16px;
    font-size: 1.1rem;
    font-weight: 700;
    border-radius: 14px;
    cursor: pointer;
    transition: all 0.2s ease;
    flex: 1;
}

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

#generate-btn:active, #reset-btn:active {
    transform: translateY(0);
}