:root {
    --bg-color: #050a10;
    --card-bg: rgba(15, 23, 42, 0.8);
    --border-color: rgba(255, 255, 255, 0.1);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #6366f1;
    --accent-hover: #818cf8;
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
    --danger-color: #ef4444;
    --success-color: #10b981;
    --font-ui: 'Inter', sans-serif;
    --font-heading: 'Outfit', sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-ui);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow-x: hidden;
}

/* Background Animation */
body::before {
    content: '';
    position: fixed;
    top: -10%;
    left: -10%;
    width: 40%;
    height: 40%;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.15) 0%, transparent 70%);
    filter: blur(80px);
    z-index: -1;
}

body::after {
    content: '';
    position: fixed;
    bottom: -10%;
    right: -10%;
    width: 40%;
    height: 40%;
    background: radial-gradient(circle, rgba(168, 85, 247, 0.15) 0%, transparent 70%);
    filter: blur(80px);
    z-index: -1;
}

.app-container {
    width: 100%;
    max-width: 1200px;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

header {
    margin-bottom: 2rem;
}

.header-main {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.help-trigger {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 999px;
    padding: 0.5rem 1.25rem;
    color: var(--text-secondary);
    font-family: var(--font-ui);
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
}

.help-trigger:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--accent-color);
    color: var(--text-primary);
}

.logo {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.brand {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.product {
    color: var(--text-primary);
    margin-left: 0.5rem;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-top: 0.5rem;
}

main {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 2rem;
}

.editor-section {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 1.5rem;
    backdrop-filter: blur(12px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.4);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.card-header h3 {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.badge {
    background: rgba(16, 185, 129, 0.2);
    color: var(--success-color);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

textarea {
    width: 100%;
    height: 150px;
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1rem;
    color: #fff;
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace; /* \ -> ₩ 변환 문제 방지 */
    font-size: 1.1rem;
    resize: none;
    outline: none;
    transition: border-color 0.3s ease;
}

textarea:focus {
    border-color: var(--accent-color);
}

.input-actions, .output-actions {
    margin-top: 1rem;
    display: flex;
    gap: 1rem;
}

.primary-btn {
    flex: 1;
    background: var(--accent-gradient);
    border: none;
    border-radius: 12px;
    padding: 0.75rem 1.5rem;
    color: white;
    font-weight: 600;
    font-family: var(--font-ui);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: opacity 0.3s ease, transform 0.2s ease;
}

.primary-btn:hover {
    opacity: 0.9;
    transform: translateY(-2px);
}

.primary-btn.outline {
    background: transparent;
    border: 1px solid var(--accent-color);
    color: var(--accent-color);
}

.primary-btn.outline:hover {
    background: rgba(99, 102, 241, 0.1);
}

.secondary-btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 0.5rem 1rem;
    color: var(--text-secondary);
    cursor: pointer;
}

.preview-area {
    min-height: 200px;
    background: rgba(255, 255, 255, 0.03);
    border: 1px dashed var(--border-color);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    overflow: auto;
    position: relative;
    background-image: radial-gradient(rgba(255, 255, 255, 0.05) 1px, transparent 1px);
    background-size: 20px 20px;
}

/* KaTeX 렌더링 순정 - 프리븷 크기만 조정, 나머지는 KaTeX 엔진 자체 처리 */
.katex-display {
    margin: 0.5em 0 !important;
    padding: 0 !important;
}

.katex {
    /* font-size만 설정 - 폰트/서체/line-height는 KaTeX에 위임 */
    font-size: 3rem !important;
}

.search-container {
    margin-bottom: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.tabs-container {
    display: flex;
    gap: 0.75rem;
    overflow-x: auto;
    padding: 0.5rem 0.25rem;
    margin-bottom: 0.5rem;
}

.tab-btn {
    padding: 0.6rem 1.25rem;
    border-radius: 30px;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.08);
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.tab-btn:hover {
    background: rgba(255, 255, 255, 0.08);
    color: var(--text-primary);
    transform: translateY(-1px);
}

.tab-btn.active {
    background: var(--accent-gradient);
    border-color: rgba(255, 255, 255, 0.2);
    color: white;
    font-weight: 700;
    box-shadow: 0 0 20px rgba(99, 102, 241, 0.4);
}

.preset-item {
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.25rem;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.preset-item:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: var(--accent-color);
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.5), 0 0 15px rgba(99, 102, 241, 0.2);
}

.preset-item::before {
    content: '';
    position: absolute;
    top: 0; left: -100%;
    width: 50%; height: 100%;
    background: linear-gradient(to right, transparent, rgba(255,255,255,0.05), transparent);
    transition: 0.5s;
}

.preset-item:hover::before {
    left: 100%;
}

.search-box {
    position: relative;
    display: flex;
    align-items: center;
}

.search-box svg {
    position: absolute;
    left: 1rem;
    color: var(--text-secondary);
}

.search-box input {
    width: 100%;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 0.75rem 1rem 0.75rem 2.5rem;
    color: var(--text-primary);
    font-family: var(--font-ui);
    outline: none;
    transition: all 0.3s ease;
}

.search-box input:focus {
    border-color: var(--accent-color);
    background: rgba(255, 255, 255, 0.08);
    box-shadow: 0 0 15px rgba(99, 102, 241, 0.2);
}

.preset-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
    max-height: 600px; /* Enable scrolling for long list */
    overflow-y: auto;
    padding-right: 0.5rem;
}

.preset-grid::-webkit-scrollbar {
    width: 6px;
}

.preset-grid::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 10px;
}

.preset-item {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    padding: 1.25rem;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    position: relative;
    overflow: hidden;
}

.preset-item:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: var(--accent-color);
    transform: translateY(-4px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.2);
}

.preset-item div:first-child {
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--text-primary);
}

.preset-math {
    /* KaTeX 순정 렌더링 - font-family 강제 제거 */
    color: var(--text-primary);
    padding: 0.25rem 0;
    overflow-x: auto;
    overflow-y: hidden;
    scrollbar-width: none;
}

.preset-math::-webkit-scrollbar {
    display: none;
}

/* 라이브러리 항목 displayMode 수식 정렬 */
.preset-math .katex {
    font-size: 1.0em !important;
}

.preset-math .katex-display {
    margin: 0 !important;
    padding: 0 !important;
}

/* Modal Styling */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(8px);
}

.modal-content {
    background-color: #0f172a;
    margin: 5% auto;
    padding: 2rem;
    border: 1px solid var(--border-color);
    border-radius: 20px;
    width: 80%;
    max-width: 800px;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    animation: modalFadeIn 0.3s ease-out;
}

@keyframes modalFadeIn {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
    margin-bottom: 1.5rem;
}

.modal-header h2 {
    font-family: var(--font-heading);
    font-size: 1.5rem;
}

.close-modal {
    color: var(--text-secondary);
    font-size: 2rem;
    font-weight: bold;
    background: none;
    border: none;
    cursor: pointer;
}

.close-modal:hover {
    color: var(--danger-color);
}

.modal-body section {
    margin-bottom: 2rem;
}

.modal-body h4 {
    color: var(--accent-hover);
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.modal-body ul {
    padding-left: 1.5rem;
    color: var(--text-secondary);
}

.modal-body li {
    margin-bottom: 0.5rem;
}

.manual-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
    background: rgba(255, 255, 255, 0.03);
    border-radius: 12px;
    overflow: hidden;
}

.manual-table th, .manual-table td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.manual-table th {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
}

.manual-table code {
    background: rgba(0, 0, 0, 0.5);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    color: var(--accent-hover);
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
}

footer {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-top: 2rem;
}

@media (max-width: 900px) {
    main {
        grid-template-columns: 1fr;
    }
}