/* ==========================================================================
   Español AI Premium Web Portal Style - v9.0
   Design: HSL Sleek Dark Mode, Glassmorphism, Responsive Grid/Flexbox
   ========================================================================== */

/* 1. Reset & Core Variables */
:root {
    --bg-main: hsl(224, 25%, 10%);
    --bg-sidebar: hsl(224, 25%, 13%);
    --bg-card: hsla(224, 25%, 16%, 0.6);
    --bg-card-hover: hsla(224, 25%, 20%, 0.85);
    
    --text-primary: hsl(210, 40%, 98%);
    --text-muted: hsl(215, 20%, 65%);
    --text-dark: hsl(224, 25%, 12%);

    --primary: hsl(243, 75%, 66%);
    --primary-hover: hsl(243, 75%, 72%);
    --primary-glow: hsla(243, 75%, 66%, 0.3);
    
    --purple: hsl(270, 70%, 60%);
    --purple-glow: hsla(270, 70%, 60%, 0.3);
    
    --accent: hsl(324, 80%, 60%);
    --success: hsl(142, 70%, 50%);
    --error: hsl(350, 80%, 55%);
    --warning: hsl(38, 92%, 50%);

    --border: hsla(224, 25%, 26%, 0.4);
    --border-hover: hsla(224, 25%, 36%, 0.6);
    
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --font-display: 'Outfit', var(--font-sans);
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.4);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: var(--font-sans);
    background-color: var(--bg-main);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    overflow-x: hidden;
    line-height: 1.6;
}

/* 2. Layout Structure */
.app-container {
    display: flex;
    width: 100vw;
    height: 100vh;
}

/* 사이드바 */
.sidebar {
    width: 280px;
    background-color: var(--bg-sidebar);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    padding: 2rem 1.5rem;
    z-index: 10;
}

.sidebar-brand {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    margin-bottom: 3rem;
}

.brand-icon {
    width: 42px;
    height: 42px;
    background: linear-gradient(135deg, var(--primary), var(--purple));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: #fff;
    box-shadow: 0 4px 12px var(--primary-glow);
}

.sidebar-brand h2 {
    font-family: var(--font-display);
    font-size: 1.4rem;
    font-weight: 700;
    background: linear-gradient(to right, #fff, hsl(210, 40%, 80%));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.sidebar-menu {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    flex-grow: 1;
}

.menu-item {
    background: none;
    border: none;
    outline: none;
    color: var(--text-muted);
    font-family: var(--font-display);
    font-size: 1rem;
    font-weight: 500;
    padding: 0.85rem 1.2rem;
    border-radius: 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 1rem;
    text-align: left;
    transition: var(--transition);
    position: relative;
}

.menu-item i {
    font-size: 1.15rem;
    width: 20px;
    transition: var(--transition);
}

.menu-item:hover {
    color: var(--text-primary);
    background-color: hsla(224, 25%, 20%, 0.4);
}

.menu-item.active {
    color: #fff;
    background: linear-gradient(to right, var(--primary), var(--purple));
    box-shadow: 0 4px 15px var(--primary-glow);
}

.menu-item.active i {
    color: #fff;
}

.menu-item .badge {
    position: absolute;
    right: 1rem;
    background-color: var(--accent);
    color: #fff;
    font-size: 0.75rem;
    padding: 0.15rem 0.5rem;
    border-radius: 20px;
    font-weight: 700;
}

.sidebar-footer {
    border-top: 1px solid var(--border);
    padding-top: 1.5rem;
    text-align: center;
}

.sidebar-footer p {
    font-size: 0.9rem;
    font-family: var(--font-display);
    font-weight: 600;
    background: linear-gradient(to right, var(--primary), var(--purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.25rem;
}

.sidebar-footer small {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* 메인 콘텐츠 */
.main-content {
    flex-grow: 1;
    height: 100vh;
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    background: radial-gradient(circle at 50% 0%, hsl(224, 25%, 15%), var(--bg-main) 70%);
}

.content-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 2rem 3rem;
    border-bottom: 1px solid var(--border);
}

.content-header h1 {
    font-family: var(--font-display);
    font-size: 2rem;
    font-weight: 800;
    letter-spacing: -0.5px;
}

.header-status {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background-color: hsla(224, 25%, 20%, 0.6);
    border: 1px solid var(--border);
    padding: 0.4rem 1rem;
    border-radius: 30px;
    font-size: 0.85rem;
}

.status-indicator {
    width: 8px;
    height: 8px;
    background-color: var(--success);
    border-radius: 50%;
    box-shadow: 0 0 8px var(--success);
}

.status-text {
    color: var(--text-muted);
    font-weight: 500;
}

.content-body {
    flex-grow: 1;
    padding: 3rem;
    overflow-y: auto;
}

/* 탭 전환 제어 */
.tab-content {
    display: none;
    animation: fadeIn 0.4s ease;
}

.tab-content.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* 3. Common Components & UI Elements */
.btn {
    border: none;
    outline: none;
    font-family: var(--font-display);
    font-size: 0.95rem;
    font-weight: 600;
    padding: 0.75rem 1.5rem;
    border-radius: 12px;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: var(--transition);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--purple));
    color: #fff;
    box-shadow: 0 4px 12px var(--primary-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 18px var(--primary-glow);
    filter: brightness(1.1);
}

.btn-secondary {
    background-color: hsla(224, 25%, 20%, 0.6);
    border: 1px solid var(--border);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background-color: hsla(224, 25%, 25%, 0.8);
    border-color: var(--border-hover);
}

.btn-success {
    background-color: var(--success);
    color: #fff;
    box-shadow: 0 4px 12px hsla(142, 70%, 50%, 0.3);
}

.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 18px hsla(142, 70%, 50%, 0.4);
    filter: brightness(1.05);
}

.btn-danger {
    background-color: var(--error);
    color: #fff;
    box-shadow: 0 4px 12px hsla(350, 80%, 55%, 0.3);
}

.btn-danger:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 18px hsla(350, 80%, 55%, 0.4);
    filter: brightness(1.05);
}

.btn-icon {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    padding: 0;
    background-color: hsla(224, 25%, 20%, 0.6);
    border: 1px solid var(--border);
    color: var(--text-primary);
}

.btn-icon:hover {
    background-color: hsla(224, 25%, 25%, 0.8);
    transform: scale(1.05);
}

.btn-large {
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    border-radius: 14px;
}

/* Spinner */
.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid hsla(224, 25%, 30%, 0.3);
    border-top: 4px solid var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* 4. Tab Specific Styles */

/* 4-1. Dashboard */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 20px;
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1.25rem;
    backdrop-filter: blur(12px);
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-4px);
    border-color: var(--border-hover);
    background-color: var(--bg-card-hover);
}

.stat-icon {
    width: 56px;
    height: 56px;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.stat-icon.purple { background-color: hsla(243, 75%, 66%, 0.15); color: var(--primary); }
.stat-icon.green { background-color: hsla(142, 70%, 50%, 0.15); color: var(--success); }
.stat-icon.orange { background-color: hsla(38, 92%, 50%, 0.15); color: var(--warning); }
.stat-icon.blue { background-color: hsla(200, 85%, 55%, 0.15); color: hsl(200, 85%, 55%); }

.stat-info h3 {
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
}

.stat-info p {
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-weight: 800;
}

.dashboard-details {
    display: grid;
    grid-template-columns: 3fr 2fr;
    gap: 2rem;
}

@media (max-width: 1024px) {
    .dashboard-details {
        grid-template-columns: 1fr;
    }
}

.detail-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 24px;
    padding: 2rem;
    backdrop-filter: blur(12px);
}

.detail-card h2 {
    font-family: var(--font-display);
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* 차트 시각화 */
.distribution-chart {
    display: flex;
    flex-direction: column;
    gap: 1.2rem;
}

.chart-row {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.chart-label {
    width: 140px;
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
}

.chart-track {
    flex-grow: 1;
    height: 12px;
    background-color: hsla(224, 25%, 10%, 0.5);
    border-radius: 6px;
    overflow: hidden;
    position: relative;
}

.chart-bar {
    height: 100%;
    background: linear-gradient(to right, var(--primary), var(--purple));
    border-radius: 6px;
    width: 0%;
    transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.chart-count {
    width: 40px;
    font-family: var(--font-display);
    font-size: 0.9rem;
    font-weight: 700;
    text-align: right;
}

/* 가이드 컴포넌트 */
.guide-content {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.guide-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
}

.guide-num {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background-color: hsla(243, 75%, 66%, 0.15);
    color: var(--primary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.9rem;
    flex-shrink: 0;
}

.guide-item p {
    font-size: 0.9rem;
    color: var(--text-muted);
}

.guide-item strong {
    color: var(--text-primary);
}

/* 4-2. Search Tab */
.search-box-container {
    max-width: 700px;
    margin: 0 auto 2.5rem;
}

.search-input-wrapper {
    display: flex;
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 0.4rem;
    align-items: center;
    gap: 0.5rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.search-input-wrapper:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 12px var(--primary-glow);
}

.search-icon {
    font-size: 1.25rem;
    color: var(--text-muted);
    margin-left: 1rem;
}

.search-input-wrapper input {
    flex-grow: 1;
    background: none;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-size: 1.05rem;
    padding: 0.6rem 0.5rem;
}

.search-input-wrapper input::placeholder {
    color: var(--text-muted);
}

.search-loader {
    text-align: center;
    padding: 3rem 0;
}

.search-loader p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

.search-result-container {
    max-width: 650px;
    margin: 0 auto;
    animation: fadeIn 0.4s ease;
}

/* 단어 정보 카드 */
.word-card {
    background: linear-gradient(135deg, var(--bg-sidebar), var(--bg-main));
    border: 1px solid var(--border);
    border-radius: 24px;
    padding: 2.5rem;
    backdrop-filter: blur(12px);
    box-shadow: var(--shadow-lg);
}

.word-card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 2rem;
}

.source-badge {
    font-size: 0.8rem;
    font-weight: 700;
    padding: 0.25rem 0.75rem;
    border-radius: 30px;
    text-transform: uppercase;
}

.source-badge.database { background-color: hsla(142, 70%, 50%, 0.15); color: var(--success); }
.source-badge.dictionary { background-color: hsla(200, 85%, 55%, 0.15); color: hsl(200, 85%, 55%); }
.source-badge.gemini { background-color: hsla(270, 70%, 60%, 0.15); color: var(--purple); }

.word-level-badge {
    background-color: var(--primary);
    color: #fff;
    font-family: var(--font-display);
    font-size: 0.9rem;
    font-weight: 800;
    padding: 0.3rem 0.85rem;
    border-radius: 8px;
}

.word-card-body h1 {
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    letter-spacing: -0.5px;
}

.word-card-body .meaning {
    font-size: 1.35rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.example-box {
    background-color: hsla(224, 25%, 10%, 0.4);
    border-left: 4px solid var(--primary);
    padding: 1.25rem;
    border-radius: 0 16px 16px 0;
    margin-bottom: 2rem;
}

.example-box h4 {
    font-size: 0.8rem;
    text-transform: uppercase;
    color: var(--text-muted);
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
}

.example-box p {
    font-size: 1.05rem;
    font-style: italic;
    color: var(--text-primary);
}

.word-card-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
}

/* 4-3. Word List Tab */
.filter-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    gap: 1.5rem;
}

@media (max-width: 768px) {
    .filter-bar {
        flex-direction: column;
        align-items: stretch;
    }
}

.filter-buttons {
    display: flex;
    background-color: hsla(224, 25%, 20%, 0.4);
    padding: 0.35rem;
    border-radius: 12px;
    border: 1px solid var(--border);
}

.filter-btn {
    background: none;
    border: none;
    outline: none;
    color: var(--text-muted);
    font-family: var(--font-display);
    font-weight: 600;
    padding: 0.5rem 1.25rem;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
}

.filter-btn:hover {
    color: var(--text-primary);
}

.filter-btn.active {
    background-color: var(--bg-main);
    color: #fff;
    box-shadow: var(--shadow-sm);
}

.word-search-wrapper {
    display: flex;
    align-items: center;
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    padding: 0.4rem 1rem;
    border-radius: 12px;
    gap: 0.5rem;
    max-width: 320px;
    width: 100%;
}

.word-search-wrapper input {
    background: none;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-size: 0.95rem;
    width: 100%;
}

.word-search-wrapper i {
    color: var(--text-muted);
}

.word-list-container {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 20px;
    overflow: hidden;
    backdrop-filter: blur(12px);
}

/* 프리미엄 테이블 스타일 */
.premium-table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
}

.premium-table th {
    background-color: hsla(224, 25%, 10%, 0.5);
    padding: 1.2rem 1.5rem;
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-bottom: 1px solid var(--border);
}

.premium-table td {
    padding: 1.2rem 1.5rem;
    font-size: 0.95rem;
    border-bottom: 1px solid var(--border);
    color: var(--text-primary);
}

.premium-table tr:last-child td {
    border-bottom: none;
}

.premium-table tr:hover td {
    background-color: hsla(224, 25%, 22%, 0.3);
}

.premium-table .table-word {
    font-family: var(--font-display);
    font-weight: 700;
    color: #fff;
}

.premium-table .table-level {
    font-family: var(--font-display);
    font-weight: 700;
    padding: 0.2rem 0.5rem;
    background-color: hsla(243, 75%, 66%, 0.15);
    color: var(--primary);
    border-radius: 4px;
    font-size: 0.8rem;
    display: inline-block;
}

.premium-table .table-stage {
    font-family: var(--font-display);
    font-weight: 700;
    color: var(--warning);
}

.premium-table .table-example {
    font-size: 0.85rem;
    color: var(--text-muted);
    max-width: 350px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.action-delete-btn {
    background: none;
    border: none;
    color: var(--error);
    cursor: pointer;
    font-size: 1rem;
    padding: 0.4rem;
    border-radius: 6px;
    transition: var(--transition);
}

.action-delete-btn:hover {
    background-color: hsla(350, 80%, 55%, 0.15);
    transform: scale(1.1);
}

.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-muted);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--border);
}

/* 4-4. Quiz Tab */
.quiz-setup-container {
    max-width: 600px;
    margin: 3rem auto 0;
    text-align: center;
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    padding: 3rem 2.5rem;
    border-radius: 24px;
    backdrop-filter: blur(12px);
    box-shadow: var(--shadow-lg);
}

.quiz-setup-container h2 {
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-weight: 800;
    margin-bottom: 1rem;
}

.quiz-desc {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 2.5rem;
}

.quiz-filter-box {
    margin-bottom: 2.5rem;
    text-align: left;
    background-color: hsla(224, 25%, 10%, 0.4);
    padding: 1.25rem;
    border-radius: 16px;
    border: 1px solid var(--border);
}

.quiz-filter-box label {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 600;
    display: block;
    margin-bottom: 0.75rem;
}

.quiz-level-selector {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.quiz-level-btn {
    background: none;
    border: 1px solid var(--border);
    color: var(--text-muted);
    font-family: var(--font-display);
    font-weight: 600;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
}

.quiz-level-btn:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
}

.quiz-level-btn.active {
    background-color: var(--primary);
    color: #fff;
    border-color: var(--primary);
    box-shadow: 0 4px 10px var(--primary-glow);
}

.quiz-play-container {
    max-width: 600px;
    margin: 1.5rem auto 0;
}

.quiz-header {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.quiz-progress-bar {
    flex-grow: 1;
    height: 8px;
    background-color: hsla(224, 25%, 20%, 0.6);
    border-radius: 4px;
    overflow: hidden;
}

.quiz-progress-fill {
    height: 100%;
    background: linear-gradient(to right, var(--primary), var(--purple));
    border-radius: 4px;
    transition: width 0.3s ease;
}

.quiz-status-text {
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 1.1rem;
}

/* 카드 뒤집기 애니메이션 */
.quiz-card-wrapper {
    perspective: 1000px;
    margin-bottom: 2rem;
}

.quiz-card {
    width: 100%;
    height: 320px;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
}

.quiz-card.flipped {
    transform: rotateY(180deg);
}

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 24px;
    border: 1px solid var(--border);
    padding: 3rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    box-shadow: var(--shadow-lg);
}

.card-front {
    background: linear-gradient(135deg, var(--bg-sidebar), var(--bg-main));
}

.card-back {
    background: linear-gradient(135deg, hsla(243, 75%, 20%, 0.3), hsla(270, 70%, 20%, 0.3));
    border-color: var(--primary);
    transform: rotateY(180deg);
}

.card-level-badge {
    position: absolute;
    top: 1.5rem;
    left: 1.5rem;
    font-family: var(--font-display);
    font-weight: 800;
    font-size: 0.85rem;
    background-color: var(--primary);
    color: #fff;
    padding: 0.25rem 0.75rem;
    border-radius: 6px;
}

.card-front h1 {
    font-family: var(--font-display);
    font-size: 3.5rem;
    font-weight: 800;
    letter-spacing: -1px;
    margin-bottom: 1rem;
    text-align: center;
}

.card-instruction {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.card-back h2 {
    font-size: 2.2rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    text-align: center;
    color: #fff;
}

.card-example-box {
    width: 100%;
    background-color: hsla(224, 25%, 10%, 0.5);
    border-left: 3px solid var(--accent);
    padding: 1rem;
    border-radius: 0 12px 12px 0;
    text-align: left;
}

.card-example-box h4 {
    font-size: 0.75rem;
    text-transform: uppercase;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
}

.card-example-box p {
    font-size: 0.95rem;
    font-style: italic;
}

.quiz-input-area {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.quiz-input-area input {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    color: var(--text-primary);
    font-size: 1.1rem;
    padding: 1rem 1.5rem;
    border-radius: 16px;
    outline: none;
    text-align: center;
    transition: var(--transition);
}

.quiz-input-area input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 10px var(--primary-glow);
}

.quiz-buttons {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 1rem;
}

.quiz-feedback-area {
    background-color: hsla(224, 25%, 15%, 0.8);
    border: 1px solid var(--border);
    border-radius: 20px;
    padding: 1.5rem;
    text-align: center;
    box-shadow: var(--shadow-md);
}

.feedback-status {
    font-size: 1.35rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.feedback-status.correct { color: var(--success); }
.feedback-status.incorrect { color: var(--error); }

.feedback-desc {
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-bottom: 1.25rem;
}

.feedback-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.quiz-result-container {
    max-width: 500px;
    margin: 3rem auto 0;
    text-align: center;
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    padding: 4rem 2.5rem;
    border-radius: 28px;
    backdrop-filter: blur(12px);
    box-shadow: var(--shadow-lg);
}

.result-celebration i {
    font-size: 4rem;
    color: var(--warning);
    margin-bottom: 1.5rem;
    animation: bounce 1s ease infinite alternate;
}

@keyframes bounce {
    from { transform: translateY(0); }
    to { transform: translateY(-10px); }
}

.result-celebration h2 {
    font-family: var(--font-display);
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.result-celebration p {
    color: var(--text-muted);
    margin-bottom: 2.5rem;
}

.result-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    margin-bottom: 3rem;
}

.result-stat-item {
    background-color: hsla(224, 25%, 10%, 0.4);
    padding: 1.25rem 0.5rem;
    border-radius: 16px;
    border: 1px solid var(--border);
}

.result-stat-item span {
    display: block;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.result-stat-item strong {
    font-family: var(--font-display);
    font-size: 1.35rem;
    font-weight: 800;
}

/* 4-5. Tutor Tab */
.tutor-container {
    max-width: 800px;
    margin: 0 auto;
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 24px;
    height: 70vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    backdrop-filter: blur(12px);
    box-shadow: var(--shadow-lg);
}

.tutor-profile {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.5rem 2rem;
    border-bottom: 1px solid var(--border);
    background-color: hsla(224, 25%, 10%, 0.3);
}

.tutor-avatar {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--primary), var(--purple));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: #fff;
}

.tutor-info h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 0.15rem;
}

.tutor-info p {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.chat-messages {
    flex-grow: 1;
    padding: 2rem;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.message {
    display: flex;
    max-width: 80%;
}

.message.bot {
    align-self: flex-start;
}

.message.user {
    align-self: flex-end;
}

.message-bubble {
    padding: 1rem 1.25rem;
    border-radius: 18px;
    font-size: 0.95rem;
}

.message.bot .message-bubble {
    background-color: hsla(224, 25%, 20%, 0.8);
    color: var(--text-primary);
    border-top-left-radius: 0;
    border: 1px solid var(--border);
}

.message.user .message-bubble {
    background: linear-gradient(135deg, var(--primary), var(--purple));
    color: #fff;
    border-top-right-radius: 0;
    box-shadow: 0 4px 10px var(--primary-glow);
}

/* AI 튜터 마크다운 답변 스타일링 */
.message-bubble p {
    margin-bottom: 0.75rem;
}
.message-bubble p:last-child {
    margin-bottom: 0;
}
.message-bubble strong {
    color: #fff;
    font-weight: 700;
}
.message-bubble ul {
    margin-left: 1.2rem;
    margin-bottom: 0.75rem;
}
.message-bubble li {
    margin-bottom: 0.25rem;
}

.chat-input-container {
    padding: 1.5rem 2rem;
    border-top: 1px solid var(--border);
    display: flex;
    gap: 1rem;
    align-items: flex-end;
    background-color: hsla(224, 25%, 10%, 0.3);
}

.chat-input-container textarea {
    flex-grow: 1;
    background-color: hsla(224, 25%, 10%, 0.6);
    border: 1px solid var(--border);
    border-radius: 14px;
    color: var(--text-primary);
    font-size: 0.95rem;
    padding: 0.75rem 1rem;
    outline: none;
    resize: none;
    font-family: var(--font-sans);
    line-height: 1.4;
    transition: var(--transition);
}

.chat-input-container textarea:focus {
    border-color: var(--primary);
}

.chat-actions {
    display: flex;
    gap: 0.5rem;
}

.stt-status-banner {
    background-color: var(--accent);
    color: #fff;
    padding: 0.5rem 2rem;
    font-size: 0.85rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* 5. Responsive Configuration */
@media (max-width: 850px) {
    .app-container {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        height: auto;
        padding: 1rem 1.5rem;
        border-right: none;
        border-bottom: 1px solid var(--border);
    }
    
    .sidebar-brand {
        margin-bottom: 1rem;
        justify-content: center;
    }
    
    .sidebar-menu {
        flex-direction: row;
        overflow-x: auto;
        padding-bottom: 0.5rem;
        gap: 0.35rem;
    }
    
    .menu-item {
        padding: 0.6rem 1rem;
        font-size: 0.9rem;
        white-space: nowrap;
    }
    
    .menu-item span {
        display: none; /* 모바일에서는 아이콘만 표시하거나 공간 줄임 */
    }
    .menu-item.active span {
        display: inline;
    }
    
    .sidebar-footer {
        display: none;
    }
    
    .main-content {
        height: calc(100vh - 130px);
    }
    
    .content-header {
        padding: 1.5rem;
    }
    
    .content-body {
        padding: 1.5rem;
    }
}